Changing the dcae dt main code

Updating DCAE-dt-main code for Dockerizing the DCAE-CI code

Change-Id: Ia50d24e60e9ddc9bbc58dd8651d7a4f7e0dc8270
Issue-ID: SDC-1605
Signed-off-by: Eran (ev672n), Vosk <ev672n@att.com>

22 files changed, 3111 insertions, 2790 deletions

diff --git a/dcaedt_validator/README b/dcaedt_validator/README
new file mode 100644
index 0000000..0291fa2
--- /dev/null
+++ b/dcaedt_validator/README
@@ -0,0 +1,9 @@
+Build commons-pipeline separately, it is not a sub-project.
+It also needs to be installed in the local repository with 'mvn install'
+
+Build the validator itself
+
+
+If runnign into problems, clear the local maven repo,
+	mvn dependency:purge-local-repository -DreResolve=false
+and start from the beginning.
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Checker.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Checker.java
index bf1843e..c75dc8d 100644
--- a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Checker.java
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Checker.java
@@ -1,7 +1,7 @@
 package org.onap.sdc.dcae.checker;
 
-import java.lang.reflect.Method;
 import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 
 import java.io.File;
 import java.io.Reader;
@@ -11,12 +11,9 @@ import java.net.URI;
 import java.net.URISyntaxException;
 
 import java.util.HashMap;
-import java.util.TreeMap;
 import java.util.Iterator;
-import java.util.ListIterator;
 import java.util.Map;
 import java.util.List;
-import java.util.LinkedList;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Set;
@@ -24,23 +21,22 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
-import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
+import com.google.common.reflect.Invokable;
 import org.onap.sdc.common.onaplog.OnapLoggerDebug;
 import org.onap.sdc.common.onaplog.OnapLoggerError;
 import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.common.*;
+import org.onap.sdc.dcae.checker.validation.TOSCAValidator;
 import org.yaml.snakeyaml.Yaml;
 
-import com.google.common.collect.Maps;
-import com.google.common.collect.MapDifference;
-import com.google.common.reflect.Invokable;
 
 import com.google.common.collect.Table;
 import com.google.common.collect.HashBasedTable;
 
 import kwalify.Validator;
 import kwalify.Rule;
-import kwalify.Types;
 import kwalify.ValidationException;
 import kwalify.SchemaException;
 
@@ -53,41 +49,34 @@ import org.reflections.Reflections;
 import org.reflections.util.FilterBuilder;
 import org.reflections.util.ConfigurationBuilder;
 import org.reflections.scanners.TypeAnnotationsScanner;
-import org.reflections.scanners.SubTypesScanner; 
+import org.reflections.scanners.SubTypesScanner;
 import org.reflections.scanners.MethodAnnotationsScanner;
 
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.INTERFACE_TYPES;
+
 /*
  * To consider: model consistency checking happens now along with validation
  * (is implemented as part of the validation hooks). It might be better to
  * separate the 2 stages and perform all the consistency checking once 
  * validation is completed.
  */
-public class Checker {
-    private static final String PROPERTIES = "properties";
-    private static final String DEFAULT = "default";
-    private static final String ATTRIBUTES = "attributes";
-    private static final String DATA_TYPES = "data_types";
-    private static final String CAPABILITY_TYPES = "capability_types";
-    private static final String VALID_SOURCE_TYPES = "valid_source_types";
-    private static final String RELATIONSHIP_TYPES = "relationship_types";
-    private static final String INTERFACES = "interfaces";
-    private static final String VALID_TARGET_TYPES = "valid_target_types";
-    private static final String ARTIFACT_TYPES = "artifact_types";
-    private static final String INTERFACE_TYPES = "interface_types";
-    private static final String NODE_TYPES = "node_types";
-    private static final String REQUIREMENTS = "requirements";
-    private static final String CAPABILITIES = "capabilities";
-    private static final String GROUP_TYPES = "group_types";
-    private static final String TARGETS_CONSTANT = "targets";
-    private static final String POLICY_TYPES = "policy_types";
-    private static final String IS_NONE_OF_THOSE = "' is none of those";
-    private static final String INPUTS = "inputs";
-    private static final String CAPABILITY = "capability";
-    private static final String ARTIFACTS = "artifacts";
-    private static final String WAS_DEFINED_FOR_THE_NODE_TYPE = " was defined for the node type ";
-    private static final String UNKNOWN = "Unknown ";
-    private static final String TYPE = " type ";
-    public static final String IMPORTED_FROM = "',imported from ";
+public class Checker implements IChecker {
+
+    private CheckCommon checkCommon;
+    private TypeCommon typeCommon;
+    private ArtifactCommon artifactCommon;
+    private CapabilityCommon capabilityCommon;
+    private FacetCommon facetCommon;
+    private GroupCommon groupCommon;
+    private InputsOutputsCommon inputsOutputsCommon;
+    private InterfaceCommon interfaceCommon;
+    private PropertiesCommon propertiesCommon;
+    private RelationshipCommon relationshipCommon;
+    private NodeCommon nodeCommon;
+    private PolicyCommon policyCommon;
+    private RequirementCommon requirementCommon;
+    private AttributesCommon attributesCommon;
 
     private Target target = null; //what we're validating at the moment
 
@@ -104,7 +93,10 @@ public class Checker {
 
     private static Catalog commonsCatalogInstance = null;
 
-    private static final String[] EMPTY_STRING_ARRAY = new String[0];
+    private static Class[] validationHookArgTypes =
+            new Class[]{Object.class, Rule.class, Validator.ValidationContext.class};
+
+
 
     /* Need a proper way to indicate where the grammars are and how they should be identified */
     private static final String[] grammarFiles = new String[]{"tosca/tosca_simple_yaml_1_0.grammar",
@@ -120,14 +112,90 @@ public class Checker {
                     new Class[]{Map.class, CheckContext.class},
                     new Class[]{List.class, CheckContext.class}};
 
-    private static Class[] validationHookArgTypes =
-            new Class[]{Object.class, Rule.class, Validator.ValidationContext.class};
+
 
     public Checker() throws CheckerException {
+        initCommons();
+
         loadGrammars();
         loadAnnotations();
     }
 
+    private void initCommons() {
+        NodeCommon.init(this);
+        InterfaceCommon.init(this);
+        checkCommon = CheckCommon.getInstance();
+        typeCommon = TypeCommon.getInstance();
+        artifactCommon = ArtifactCommon.getInstance();
+        capabilityCommon = CapabilityCommon.getInstance();
+        facetCommon = FacetCommon.getInstance();
+        groupCommon = GroupCommon.getInstance();
+        inputsOutputsCommon = InputsOutputsCommon.getInstance();
+        interfaceCommon = InterfaceCommon.getInstance();
+        propertiesCommon = PropertiesCommon.getInstance();
+        relationshipCommon = RelationshipCommon.getInstance();
+        nodeCommon = NodeCommon.getInstance();
+        policyCommon = PolicyCommon.getInstance();
+        requirementCommon = RequirementCommon.getInstance();
+        attributesCommon = AttributesCommon.getInstance();
+    }
+
+    @FunctionalInterface
+    interface Function<A, B, C, D> {
+        void function(String key, Map value, Checker.CheckContext theContext, Catalog catalog);
+
+    }
+
+    @FunctionalInterface
+    interface FunctionWithoutCatalog<A, B, C> {
+        void function(String key, Map value, Checker.CheckContext theContext);
+
+    }
+    @FunctionalInterface
+    interface FunctionWithTarget<A, B, C, D, E> {
+        void function(String key, Map value, Checker.CheckContext theContext, Catalog catalog, Target target);
+    }
+
+    private void abstractCheck(Function function, Map<String, Map> stringMapMap, Checker.CheckContext theContext, String type) {
+        theContext.enter(type);
+        try {
+            if (!checkCommon.checkDefinition(type, stringMapMap, theContext)) {
+                return;
+            }
+
+            stringMapMap.forEach((key, value) -> function.function(key, value, theContext, catalog));
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    private void abstractCheck(FunctionWithoutCatalog function, Map<String, Map> stringMapMap, Checker.CheckContext theContext, String type) {
+        theContext.enter(type);
+        try {
+            if (!checkCommon.checkDefinition(type, stringMapMap, theContext)) {
+                return;
+            }
+
+            stringMapMap.forEach((key, value) -> function.function(key, value, theContext));
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    private void abstractCheck(FunctionWithTarget function, Map<String, Map> stringMapMap, Checker.CheckContext theContext, String type) {
+        theContext.enter(type);
+        try {
+            if (!checkCommon.checkDefinition(type, stringMapMap, theContext)) {
+                return;
+            }
+
+            stringMapMap.forEach((key, value) -> function.function(key, value, theContext, catalog, target));
+        } finally {
+            theContext.exit();
+        }
+    }
+
+
     public static void main(String[] theArgs) {
         if (theArgs.length == 0) {
             errLogger.log(LogLevel.ERROR, Checker.class.getName(), "checker resource_to_validate [processor]*");
@@ -137,13 +205,9 @@ public class Checker {
         try {
             Catalog cat = Checker.check(new File(theArgs[0]));
 
-            for (Target t : cat.targets()) {
-                errLogger.log(LogLevel.ERROR, Checker.class.getName(), "{}\n{}\n{}", t.getLocation(), cat.importString(t), t.getReport());
-            }
+            cat.targets().forEach(t -> errLogger.log(LogLevel.ERROR, Checker.class.getName(), "{}\n{}\n{}", t.getLocation(), cat.importString(t), t.getReport()));
 
-            for (Target t : cat.sortedTargets()) {
-                errLogger.log(LogLevel.ERROR, Checker.class.getName(), t.toString());
-            }
+            cat.sortedTargets().forEach(t -> errLogger.log(LogLevel.ERROR, Checker.class.getName(), t.toString()));
 
         } catch (Exception x) {
             errLogger.log(LogLevel.ERROR, Checker.class.getName(),"Exception {}", x);
@@ -206,34 +270,30 @@ public class Checker {
         Map<Class, Object> handlers = new HashMap<>();
 
         Set<Method> checkHandlers = reflections.getMethodsAnnotatedWith(Checks.class);
-        for (Method checkHandler : checkHandlers) {
-            checks.put(checkHandler.getAnnotation(Checks.class).path(),
-                    checkHandler,
-                    handlers.computeIfAbsent(checkHandler.getDeclaringClass(),
-                            type -> {
-                                try {
-                                    return (getClass() == type) ? this
-                                            : type.newInstance();
-                                } catch (Exception x) {
-                                    throw new RuntimeException(x);
-                                }
-                            }));
-        }
+        checkHandlers.forEach(checkHandler -> checks.put(checkHandler.getAnnotation(Checks.class).path(),
+                checkHandler,
+                handlers.computeIfAbsent(checkHandler.getDeclaringClass(),
+                        type -> {
+                            try {
+                                return (getClass() == type) ? this
+                                        : type.newInstance();
+                            } catch (Exception x) {
+                                throw new RuntimeException(x);
+                            }
+                        })));
 
         Set<Method> catalogHandlers = reflections.getMethodsAnnotatedWith(Catalogs.class);
-        for (Method catalogHandler : catalogHandlers) {
-            catalogs.put(catalogHandler.getAnnotation(Catalogs.class).path(),
-                    catalogHandler,
-                    handlers.computeIfAbsent(catalogHandler.getDeclaringClass(),
-                            type -> {
-                                try {
-                                    return (getClass() == type) ? this
-                                            : type.newInstance();
-                                } catch (Exception x) {
-                                    throw new RuntimeException(x);
-                                }
-                            }));
-        }
+        catalogHandlers.forEach(catalogHandler -> catalogs.put(catalogHandler.getAnnotation(Catalogs.class).path(),
+                catalogHandler,
+                handlers.computeIfAbsent(catalogHandler.getDeclaringClass(),
+                        type -> {
+                            try {
+                                return (getClass() == type) ? this
+                                        : type.newInstance();
+                            } catch (Exception x) {
+                                throw new RuntimeException(x);
+                            }
+                        })));
     }
 
 
@@ -341,7 +401,7 @@ public class Checker {
             throws CheckerException {
         debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "parseTarget {}", theTarget);
 
-        Reader source = null;
+        Reader source;
         try {
             source = theTarget.open();
         } catch (IOException iox) {
@@ -375,15 +435,15 @@ public class Checker {
             targets.add(theTarget);
         } else {
             //the target turned out to be a stream containing multiple documents
-            for (int i = 0; i < yamlRoots.size(); i++) {
-/*
-!!We're changing the target below, i.e. we're changing the target implementation hence caching implementation will suffer!!
-*/
+            /*
+            !!We're changing the target below, i.e. we're changing the target implementation hence caching implementation will suffer!!
+            */
+            IntStream.range(0, yamlRoots.size()).forEach(i -> {
                 Target newTarget = new Target(theTarget.getName(),
                         fragmentTargetURI(theTarget.getLocation(), String.valueOf(i)));
                 newTarget.setTarget(yamlRoots.get(i));
                 targets.add(newTarget);
-            }
+            });
         }
 
         debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), getClass().getName(), " exiting parseTarget {}", theTarget);
@@ -418,7 +478,7 @@ public class Checker {
 
         TOSCAValidator validator = null;
         try {
-            validator = new TOSCAValidator(theTarget, grammar.getTarget());
+            validator = new TOSCAValidator(theTarget, grammar.getTarget(), this);
         } catch (SchemaException sx) {
             throw new CheckerException("Grammar error at: " + sx.getPath(), sx);
         }
@@ -427,7 +487,7 @@ public class Checker {
                 validator.validate(theTarget.getTarget()));
 
         if (!theTarget.getReport().hasErrors()) {
-            applyCanonicals(theTarget.getTarget(), validator.canonicals);
+            applyCanonicals(theTarget.getTarget(), validator.getCanonicals());
         }
 
         debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), getClass().getName(), " exiting validateTarget {}", theTarget);
@@ -447,74 +507,6 @@ public class Checker {
         return theTarget;
     }
 
-    public void checkProperties(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(PROPERTIES);
-        try {
-            if (!checkDefinition(PROPERTIES, theDefinitions, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkPropertyDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkPropertyDefinition(
-            String theName, Map theDefinition, CheckContext theContext) {
-        theContext.enter(theName);
-        if (!checkDefinition(theName, theDefinition, theContext)) {
-            return;
-        }
-        //check the type
-        if (!checkDataType(theDefinition, theContext)) {
-            return;
-        }
-        //check default value is compatible with type
-        Object defaultValue = theDefinition.get(DEFAULT);
-        if (defaultValue != null) {
-            checkDataValuation(defaultValue, theDefinition, theContext);
-        }
-
-        theContext.exit();
-    }
-
-    private void checkAttributes(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(ATTRIBUTES);
-        try {
-            if (!checkDefinition(ATTRIBUTES, theDefinitions, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkAttributeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkAttributeDefinition(
-            String theName, Map theDefinition, CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-            if (!checkDataType(theDefinition, theContext)) {
-                return;
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
     /* top level rule, we collected the whole information set.
      * this is where checking starts
      */
@@ -530,760 +522,12 @@ public class Checker {
 //!!! imports need to be processed first now that catalogging takes place at check time!! 
 
         //first catalog whatever it is there to be cataloged so that the checks can perform cross-checking
-        for (Iterator<Map.Entry<String, Object>> ri = theDef.entrySet().iterator();
-             ri.hasNext(); ) {
-            Map.Entry<String, Object> e = ri.next();
-            catalogs(e.getKey(), e.getValue(), theContext);
-        }
+        theDef.forEach((key, value) -> catalogs(key, value, theContext));
 
-        for (Iterator<Map.Entry<String, Object>> ri = theDef.entrySet().iterator();
-             ri.hasNext(); ) {
-            Map.Entry<String, Object> e = ri.next();
-            checks(e.getKey(), e.getValue(), theContext);
-        }
+        theDef.forEach((key, value) -> checks(key, value, theContext));
         theContext.exit();
     }
 
-    @Catalogs(path = "/data_types")
-    protected void catalog_data_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(DATA_TYPES);
-        try {
-            catalogTypes(Construct.Data, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/data_types")
-    protected void check_data_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(DATA_TYPES);
-
-        try {
-            if (!checkDefinition(DATA_TYPES, theDefinitions, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkDataTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkDataTypeDefinition(String theName,
-                                         Map theDefinition,
-                                         CheckContext theContext) {
-        theContext.enter(theName, Construct.Data);
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Data, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/capability_types")
-    protected void catalog_capability_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(CAPABILITY_TYPES);
-        try {
-            catalogTypes(Construct.Capability, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/capability_types")
-    protected void check_capability_types(
-            Map<String, Map> theTypes, CheckContext theContext) {
-        theContext.enter(CAPABILITY_TYPES);
-        try {
-            if (!checkDefinition(CAPABILITY_TYPES, theTypes, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theTypes.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkCapabilityTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkCapabilityTypeDefinition(String theName,
-                                               Map theDefinition,
-                                               CheckContext theContext) {
-        theContext.enter(theName, Construct.Capability);
-
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Capability, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-
-            if (theDefinition.containsKey(ATTRIBUTES)) {
-                checkAttributes(
-                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext);
-                checkTypeConstructFacet(Construct.Capability, theName, theDefinition,
-                        Facet.attributes, theContext);
-            }
-
-            //valid_source_types: see capability_type_definition
-            //unclear: how is the valid_source_types list definition eveolving across
-            //the type hierarchy: additive, overwriting, ??
-            if (theDefinition.containsKey(VALID_SOURCE_TYPES)) {
-                checkTypeReference(Construct.Node, theContext,
-                        ((List<String>) theDefinition.get(VALID_SOURCE_TYPES)).toArray(EMPTY_STRING_ARRAY));
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/relationship_types")
-    protected void catalog_relationship_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(RELATIONSHIP_TYPES);
-        try {
-            catalogTypes(Construct.Relationship, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/relationship_types")
-    protected void check_relationship_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(RELATIONSHIP_TYPES);
-        try {
-            if (!checkDefinition(RELATIONSHIP_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkRelationshipTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkRelationshipTypeDefinition(String theName,
-                                                 Map theDefinition,
-                                                 CheckContext theContext) {
-        theContext.enter(theName, Construct.Relationship);
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Relationship, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-
-            if (theDefinition.containsKey(ATTRIBUTES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext);
-                checkTypeConstructFacet(Construct.Relationship, theName, theDefinition,
-                        Facet.attributes, theContext);
-            }
-
-            Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get(INTERFACES);
-            if (interfaces != null) {
-                theContext.enter(INTERFACES);
-                for (Iterator<Map.Entry<String, Map>> i =
-                     interfaces.entrySet().iterator(); i.hasNext(); ) {
-                    Map.Entry<String, Map> e = i.next();
-                    check_type_interface_definition(
-                            e.getKey(), e.getValue(), theContext);
-                }
-                theContext.exit();
-            }
-
-            if (theDefinition.containsKey(VALID_TARGET_TYPES)) {
-                checkTypeReference(Construct.Capability, theContext,
-                        ((List<String>) theDefinition.get(VALID_TARGET_TYPES)).toArray(EMPTY_STRING_ARRAY));
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/artifact_types")
-    protected void catalog_artifact_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(ARTIFACT_TYPES);
-        try {
-            catalogTypes(Construct.Artifact, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/artifact_types")
-    protected void check_artifact_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(ARTIFACT_TYPES);
-        try {
-            if (!checkDefinition(ARTIFACT_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkArtifactTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkArtifactTypeDefinition(String theName,
-                                             Map theDefinition,
-                                             CheckContext theContext) {
-        theContext.enter(theName, Construct.Artifact);
-        try {
-            checkDefinition(theName, theDefinition, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/interface_types")
-    protected void catalog_interface_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(INTERFACE_TYPES);
-        try {
-            catalogTypes(Construct.Interface, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/interface_types")
-    protected void check_interface_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(INTERFACE_TYPES);
-        try {
-            if (!checkDefinition(INTERFACE_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkInterfaceTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkInterfaceTypeDefinition(String theName,
-                                              Map theDefinition,
-                                              CheckContext theContext) {
-        theContext.enter(theName, Construct.Interface);
-        try {
-            checkDefinition(theName, theDefinition, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/node_types")
-    protected void catalog_node_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(NODE_TYPES);
-        try {
-            catalogTypes(Construct.Node, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/node_types")
-    protected void check_node_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(NODE_TYPES);
-        try {
-            if (!checkDefinition(NODE_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkNodeTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkNodeTypeDefinition(String theName,
-                                         Map theDefinition,
-                                         CheckContext theContext) {
-        theContext.enter(theName, Construct.Node);
-
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Node, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-
-            if (theDefinition.containsKey(ATTRIBUTES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext);
-                checkTypeConstructFacet(Construct.Node, theName, theDefinition,
-                        Facet.attributes, theContext);
-            }
-
-            //requirements
-            if (theDefinition.containsKey(REQUIREMENTS)) {
-                check_requirements(
-                        (List<Map>) theDefinition.get(REQUIREMENTS), theContext);
-            }
-
-            //capabilities
-            if (theDefinition.containsKey(CAPABILITIES)) {
-                check_capabilities(
-                        (Map<String, Map>) theDefinition.get(CAPABILITIES), theContext);
-            }
-
-            //interfaces:
-            Map<String, Map> interfaces =
-                    (Map<String, Map>) theDefinition.get(INTERFACES);
-            checkMapTypeInterfaceDefinition(theContext, interfaces);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkMapTypeInterfaceDefinition(CheckContext theContext, Map<String, Map> interfaces) {
-        if (interfaces != null) {
-            try {
-                theContext.enter(INTERFACES);
-                for (Iterator<Map.Entry<String, Map>> i =
-                     interfaces.entrySet().iterator(); i.hasNext(); ) {
-                    Map.Entry<String, Map> e = i.next();
-                    check_type_interface_definition(
-                            e.getKey(), e.getValue(), theContext);
-                }
-            } finally {
-                theContext.exit();
-            }
-        }
-    }
-
-    @Catalogs(path = "/group_types")
-    protected void catalog_group_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(GROUP_TYPES);
-        try {
-            catalogTypes(Construct.Group, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/group_types")
-    protected void check_group_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(GROUP_TYPES);
-        try {
-            if (!checkDefinition(GROUP_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkGroupTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkGroupTypeDefinition(String theName,
-                                          Map theDefinition,
-                                          CheckContext theContext) {
-        theContext.enter(theName, Construct.Group);
-
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Group, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-
-            if (theDefinition.containsKey(TARGETS_CONSTANT)) {
-                checkTypeReference(Construct.Node, theContext,
-                        ((List<String>) theDefinition.get(TARGETS_CONSTANT)).toArray(EMPTY_STRING_ARRAY));
-            }
-
-            //interfaces
-            Map<String, Map> interfaces =
-                    (Map<String, Map>) theDefinition.get(INTERFACES);
-            checkMapTypeInterfaceDefinition(theContext, interfaces);
-
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Catalogs(path = "/policy_types")
-    protected void catalog_policy_types(
-            Map<String, Map> theDefinitions, CheckContext theContext) {
-        theContext.enter(POLICY_TYPES);
-        try {
-            catalogTypes(Construct.Policy, theDefinitions, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/policy_types")
-    protected void check_policy_types(
-            Map<String, Map> theDefinition, CheckContext theContext) {
-        theContext.enter(POLICY_TYPES);
-        try {
-            if (!checkDefinition(POLICY_TYPES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkPolicyTypeDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkPolicyTypeDefinition(String theName,
-                                           Map theDefinition,
-                                           CheckContext theContext) {
-        theContext.enter(theName, Construct.Policy);
-
-        try {
-            if (!checkDefinition(theName, theDefinition, theContext)) {
-                return;
-            }
-
-            if (theDefinition.containsKey(PROPERTIES)) {
-                checkProperties(
-                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-                checkTypeConstructFacet(Construct.Policy, theName, theDefinition,
-                        Facet.properties, theContext);
-            }
-
-            //the targets can be known node types or group types
-            List<String> targets = (List<String>) theDefinition.get(TARGETS_CONSTANT);
-            if ((targets != null) && (checkDefinition(TARGETS_CONSTANT, targets, theContext))) {
-                for (String targetItr : targets) {
-                    if (!(this.catalog.hasType(Construct.Node, targetItr) ||
-                            this.catalog.hasType(Construct.Group, targetItr))) {
-                        theContext.addError("The 'targets' entry must contain a reference to a node type or group type, '" + target + IS_NONE_OF_THOSE, null);
-                    }
-                }
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    //checking of actual constructs (capability, ..)
-
-    /* First, interface types do not have a hierarchical organization (no
-     * 'derived_from' in a interface type definition).
-     * So, when interfaces (with a certain type) are defined in a node
-     * or relationship type (and they can define new? operations), what
-     * is there to check:
-     * 	Can operations here re-define their declaration from the interface
-     * type spec?? From A.5.11.3 we are to understand indicates override to be
-     * the default interpretation .. but they talk about sub-classing so it
-     * probably intended as a reference to the node or relationship type
-     * hierarchy and not the interface type (no hierarchy there).
-     *	Or is this a a case of augmentation where new operations can be added??
-     */
-    private void check_type_interface_definition(
-            String theName, Map theDef, CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-
-            if (!checkType(Construct.Interface, theDef, theContext)) {
-                return;
-            }
-
-            if (theDef.containsKey(INPUTS)) {
-                check_inputs((Map<String, Map>) theDef.get(INPUTS), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void check_capabilities(Map<String, Map> theDefinition,
-                                   CheckContext theContext) {
-        theContext.enter(CAPABILITIES);
-        try {
-            if (!checkDefinition(CAPABILITIES, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkCapabilityDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* A capability definition appears within the context ot a node type */
-    private void checkCapabilityDefinition(String theName,
-                                           Map theDef,
-                                           CheckContext theContext) {
-        theContext.enter(theName, Construct.Capability);
-
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-
-            //check capability type
-            if (!checkType(Construct.Capability, theDef, theContext)) {
-                return;
-            }
-
-            //check properties
-            if (!checkFacetAugmentation(
-                    Construct.Capability, theDef, Facet.properties, theContext)) {
-                return;
-            }
-
-            //check attributes
-            if (!checkFacetAugmentation(
-                    Construct.Capability, theDef, Facet.attributes, theContext)) {
-                return;
-            }
-
-            //valid_source_types: should point to valid template nodes
-            if (theDef.containsKey(VALID_SOURCE_TYPES)) {
-                checkTypeReference(Construct.Node, theContext,
-                        ((List<String>) theDef.get(VALID_SOURCE_TYPES)).toArray(EMPTY_STRING_ARRAY));
-                //per A.6.1.4 there is an additinal check to be performed here:
-                //"Any Node Type (names) provides as values for the valid_source_types keyname SHALL be type-compatible (i.e., derived from the same parent Node Type) with any Node Types defined using the same keyname in the parent Capability Type."
-            }
-            //occurences: were verified in range_definition
-
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void check_requirements(List<Map> theDefinition,
-                                   CheckContext theContext) {
-        theContext.enter(REQUIREMENTS);
-        try {
-            if (!checkDefinition(REQUIREMENTS, theDefinition, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map> i = theDefinition.iterator(); i.hasNext(); ) {
-                Map e = i.next();
-                Iterator<Map.Entry<String, Map>> ei =
-                        (Iterator<Map.Entry<String, Map>>) e.entrySet().iterator();
-                Map.Entry<String, Map> eie = ei.next();
-                checkRequirementDefinition(eie.getKey(), eie.getValue(), theContext);
-                assert !ei.hasNext();
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkRequirementDefinition(String theName,
-                                            Map theDef,
-                                            CheckContext theContext) {
-        theContext.enter(theName, Construct.Requirement);
-
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-            //check capability type
-            String capabilityType = (String) theDef.get(CAPABILITY);
-            if (null != capabilityType) {
-                checkTypeReference(Construct.Capability, theContext, capabilityType);
-            }
-
-            //check node type
-            String nodeType = (String) theDef.get("node");
-            if (null != nodeType) {
-                checkTypeReference(Construct.Node, theContext, nodeType);
-            }
-
-            //check relationship type
-            Map relationshipSpec = (Map) theDef.get("relationship");
-            String relationshipType = null;
-            if (null != relationshipSpec) {
-                relationshipType = (String) relationshipSpec.get("type");
-                if (relationshipType != null) { //should always be the case
-                    checkTypeReference(Construct.Relationship, theContext, relationshipType);
-                }
-
-                Map<String, Map> interfaces = (Map<String, Map>)
-                        relationshipSpec.get(INTERFACES);
-                if (interfaces != null) {
-                    //augmentation (additional properties or operations) of the interfaces
-                    //defined by the above relationship types
-
-                    //check that the interface types are known
-                    for (Map interfaceDef : interfaces.values()) {
-                        checkType(Construct.Interface, interfaceDef, theContext);
-                    }
-                }
-            }
-
-            //cross checks
-
-            //the capability definition might come from the capability type or from the capability definition
-            //within the node type. We might have more than one as a node might specify multiple capabilities of the
-            //same type.
-            //the goal here is to cross check the compatibility of the valid_source_types specification in the
-            //target capability definition (if that definition contains a valid_source_types entry).
-            List<Map> capabilityDefs = new LinkedList<>();
-            //nodeType exposes capabilityType
-            if (nodeType != null) {
-                Map<String, Map> capabilities =
-                        findTypeFacetByType(Construct.Node, nodeType,
-                                Facet.capabilities, capabilityType);
-                if (capabilities.isEmpty()) {
-                    theContext.addError("The node type " + nodeType + " does not appear to expose a capability of a type compatible with " + capabilityType, null);
-                } else {
-                    for (Map.Entry<String, Map> capability : capabilities.entrySet()) {
-                        //this is the capability as it was defined in the node type
-                        Map capabilityDef = capability.getValue();
-                        //if it defines a valid_source_types then we're working with it,
-                        //otherwise we're working with the capability type it points to.
-                        //The spec does not make it clear if the valid_source_types in a capability definition augments or
-                        //overwrites the one from the capabilityType (it just says they must be compatible).
-                        if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
-                            capabilityDefs.add(capabilityDef);
-                        } else {
-                            capabilityDef =
-                                    catalog.getTypeDefinition(Construct.Capability, (String) capabilityDef.get("type"));
-                            if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
-                                capabilityDefs.add(capabilityDef);
-                            } else {
-                                //!!if there is a capability that does not have a valid_source_type than there is no reason to
-                                //make any further verification (as there is a valid node_type/capability target for this requirement)
-                                capabilityDefs.clear();
-                                break;
-                            }
-                        }
-                    }
-                }
-            } else {
-                Map capabilityDef = catalog.getTypeDefinition(Construct.Capability, capabilityType);
-                if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
-                    capabilityDefs.add(capabilityDef);
-                }
-            }
-
-            //check that the node type enclosing this requirement definition
-            //is in the list of valid_source_types
-            if (!capabilityDefs.isEmpty()) {
-                String enclosingNodeType =
-                        theContext.enclosingConstruct(Construct.Node);
-                assert enclosingNodeType != null;
-
-                if (!capabilityDefs.stream().anyMatch(
-                        (Map capabilityDef) -> {
-                            List<String> valid_source_types =
-                                    (List<String>) capabilityDef.get(VALID_SOURCE_TYPES);
-                            return valid_source_types.stream().anyMatch(
-                                    (String source_type) -> catalog.isDerivedFrom(
-                                            Construct.Node, enclosingNodeType, source_type));
-                        })) {
-                    theContext.addError("Node type: " + enclosingNodeType + " not compatible with any of the valid_source_types provided in the definition of compatible capabilities", null);
-                }
-            }
-
-            //if we have a relationship type, check if it has a valid_target_types
-            //if it does, make sure that the capability type is compatible with one
-            //of them
-            if (relationshipType != null) { //should always be the case
-                Map relationshipTypeDef = catalog.getTypeDefinition(
-                        Construct.Relationship, relationshipType);
-                if (relationshipTypeDef != null) {
-                    List<String> valid_target_types =
-                            (List<String>) relationshipTypeDef.get(VALID_TARGET_TYPES);
-                    if (valid_target_types != null) {
-                        boolean found = false;
-                        for (String target_type : valid_target_types) {
-                            if (catalog.isDerivedFrom(
-                                    Construct.Capability, capabilityType, target_type)) {
-                                found = true;
-                                break;
-                            }
-                        }
-                        if (!found) {
-                            theContext.addError("Capability type: " + capabilityType + " not compatible with any of the valid_target_types " + valid_target_types + " provided in the definition of relationship type " + relationshipType, null);
-                        }
-                    }
-                }
-            }
-
-            //relationship declares the capabilityType in its valid_target_type set
-            //in A.6.9 'Relationship Type' the spec does not indicate how	inheritance
-            //is to be applied to the valid_target_type spec: cumulative, overwrites,
-            //so we treat it as an overwrite.
-        } finally {
-            theContext.exit();
-        }
-    }
 
     //topology_template_definition and sub-rules
     /* */
@@ -1308,8 +552,7 @@ public class Checker {
     protected void check_imports(List theImports, CheckContext theContext) {
         theContext.enter("imports");
 
-        for (ListIterator li = theImports.listIterator(); li.hasNext(); ) {
-            Object importEntry = li.next();
+        for (Object importEntry : theImports) {
             Object importFile = ((Map) mapEntry(importEntry).getValue()).get("file");
             Target tgt = null;
             try {
@@ -1331,1360 +574,11 @@ public class Checker {
         theContext.exit();
     }
 
-    /* */
-    @Checks(path = "/topology_template/substitution_mappings")
-    protected void check_substitution_mappings(Map<String, Object> theSub,
-                                               CheckContext theContext) {
-        theContext.enter("substitution_mappings");
-        try {
-            //type is mandatory
-            String type = (String) theSub.get("node_type");
-            if (!checkTypeReference(Construct.Node, theContext, type)) {
-                theContext.addError("Unknown node type: " + type + "", null);
-                return; //not much to go on with
-            }
-
-            Map<String, List> capabilities = (Map<String, List>) theSub.get(CAPABILITIES);
-            if (null != capabilities) {
-                for (Map.Entry<String, List> ce : capabilities.entrySet()) {
-                    //the key must be a capability of the type
-                    if (null == findTypeFacetByName(Construct.Node, type,
-                            Facet.capabilities, ce.getKey())) {
-                        theContext.addError("Unknown node type capability: " + ce.getKey() + ", type " + type, null);
-                    }
-                    //the value is a 2 element list: first is a local node,
-                    //second is the name of one of its capabilities
-                    List targetList = ce.getValue();
-                    if (targetList.size() != 2) {
-                        theContext.addError("Invalid capability mapping: " + target + ", expecting 2 elements", null);
-                        continue;
-                    }
-
-                    String targetNode = (String) targetList.get(0);
-                    String targetCapability = (String) targetList.get(1);
-
-                    Map<String, Object> targetNodeDef = (Map<String, Object>)
-                            this.catalog.getTemplate(theContext.target(), Construct.Node, targetNode);
-                    if (null == targetNodeDef) {
-                        theContext.addError("Invalid capability mapping node template: " + targetNode, null);
-                        continue;
-                    }
-
-                    String targetNodeType = (String) targetNodeDef.get("type");
-                    if (null == findTypeFacetByName(Construct.Node, targetNodeType,
-                            Facet.capabilities, targetCapability)) {
-                        theContext.addError("Invalid capability mapping capability: " + targetCapability + ". No such capability found for node template " + targetNode + ", of type " + targetNodeType, null);
-                    }
-                }
-            }
-
-            Map<String, List> requirements = (Map<String, List>) theSub.get(REQUIREMENTS);
-            if (null != requirements) {
-                for (Map.Entry<String, List> re : requirements.entrySet()) {
-                    //the key must be a requirement of the type
-                    if (null == findNodeTypeRequirementByName(type, re.getKey())) {
-                        theContext.addError("Unknown node type requirement: " + re.getKey() + ", type " + type, null);
-                    }
-
-                    List targetList = re.getValue();
-                    if (targetList.size() != 2) {
-                        theContext.addError("Invalid requirement mapping: " + targetList + ", expecting 2 elements", null);
-                        continue;
-                    }
-
-                    String targetNode = (String) targetList.get(0);
-                    String targetRequirement = (String) targetList.get(1);
-
-                    Map<String, Object> targetNodeDef = (Map<String, Object>)
-                            this.catalog.getTemplate(theContext.target(), Construct.Node, targetNode);
-                    if (null == targetNodeDef) {
-                        theContext.addError("Invalid requirement mapping node template: " + targetNode, null);
-                        continue;
-                    }
-
-                    String targetNodeType = (String) targetNodeDef.get("type");
-                    if (null == findNodeTypeRequirementByName(targetNodeType, targetRequirement)) {
-                        theContext.addError("Invalid requirement mapping requirement: " + targetRequirement + ". No such requirement found for node template " + targetNode + ", of type " + targetNodeType, null);
-                    }
-                }
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-
-    /* */
-    @Checks(path = "/topology_template/inputs")
-    protected void check_inputs(Map<String, Map> theInputs,
-                                CheckContext theContext) {
-        theContext.enter(INPUTS);
-
-        try {
-            if (!checkDefinition(INPUTS, theInputs, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theInputs.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkInputDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkInputDefinition(String theName,
-                                      Map theDef,
-                                      CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-            //
-            if (!checkDataType(theDef, theContext)) {
-                return;
-            }
-            //check default value
-            Object defaultValue = theDef.get(DEFAULT);
-            if (defaultValue != null) {
-                checkDataValuation(defaultValue, theDef, theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "topology_template/outputs")
-    protected void check_outputs(Map<String, Map> theOutputs,
-                                 CheckContext theContext) {
-        theContext.enter("outputs");
-
-        try {
-            if (!checkDefinition("outputs", theOutputs, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theOutputs.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkOutputDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkOutputDefinition(String theName,
-                                       Map theDef,
-                                       CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            checkDefinition(theName, theDef, theContext);
-            //check the expression
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/topology_template/groups")
-    protected void check_groups(Map<String, Map> theGroups,
-                                CheckContext theContext) {
-        theContext.enter("groups");
-
-        try {
-            if (!checkDefinition("groups", theGroups, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theGroups.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkGroupDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkGroupDefinition(String theName,
-                                      Map theDef,
-                                      CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-
-            if (!checkType(Construct.Group, theDef, theContext)) {
-                return;
-            }
-
-            if (!checkFacet(
-                    Construct.Group, theDef, Facet.properties, theContext)) {
-                return;
-            }
-
-            if (theDef.containsKey(TARGETS_CONSTANT)) {
-
-                List<String> targetsTypes = (List<String>)
-                        this.catalog.getTypeDefinition(Construct.Group,
-                                (String) theDef.get("type"))
-                                .get(TARGETS_CONSTANT);
-
-                List<String> targets = (List<String>) theDef.get(TARGETS_CONSTANT);
-                for (String targetItr : targets) {
-                    if (!this.catalog.hasTemplate(theContext.target(), Construct.Node, targetItr)) {
-                        theContext.addError("The 'targets' entry must contain a reference to a node template, '" + targetItr + "' is not one", null);
-                    } else {
-                        if (targetsTypes != null) {
-                            String targetType = (String)
-                                    this.catalog.getTemplate(theContext.target(), Construct.Node, targetItr).get("type");
-
-                            boolean found = false;
-                            for (String type : targetsTypes) {
-                                found = this.catalog
-                                        .isDerivedFrom(Construct.Node, targetType, type);
-                                if (found) {
-                                    break;
-                                }
-                            }
-
-                            if (!found) {
-                                theContext.addError("The 'targets' entry '" + targetItr + "' is not type compatible with any of types specified in policy type targets", null);
-                            }
-                        }
-                    }
-                }
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/topology_template/policies")
-    protected void check_policies(List<Map<String, Map>> thePolicies,
-                                  CheckContext theContext) {
-        theContext.enter("policies");
-
-        try {
-            if (!checkDefinition("policies", thePolicies, theContext)) {
-                return;
-            }
-
-            for (Map<String, Map> policy : thePolicies) {
-                assert policy.size() == 1;
-                Map.Entry<String, Map> e = policy.entrySet().iterator().next();
-                checkPolicyDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkPolicyDefinition(String theName,
-                                       Map theDef,
-                                       CheckContext theContext) {
-        theContext.enter(theName);
-        try {
-            if (!checkDefinition(theName, theDef, theContext)) {
-                return;
-            }
-
-            if (!checkType(Construct.Policy, theDef, theContext)) {
-                return;
-            }
-
-            if (!checkFacet(
-                    Construct.Policy, theDef, Facet.properties, theContext)) {
-                return;
-            }
-
-            //targets: must point to node or group templates (that are of a type
-            //specified in the policy type definition, if targets were specified
-            //there).
-            if (theDef.containsKey(TARGETS_CONSTANT)) {
-                List<String> targetsTypes = (List<String>)
-                        this.catalog.getTypeDefinition(Construct.Policy,
-                                (String) theDef.get("type"))
-                                .get(TARGETS_CONSTANT);
-
-                List<String> targets = (List<String>) theDef.get(TARGETS_CONSTANT);
-                for (String targetItr : targets) {
-                    Construct targetConstruct = null;
-
-                    if (this.catalog.hasTemplate(theContext.target(), Construct.Group, targetItr)) {
-                        targetConstruct = Construct.Group;
-                    } else if (this.catalog.hasTemplate(theContext.target(), Construct.Node, targetItr)) {
-                        targetConstruct = Construct.Node;
-                    } else {
-                        theContext.addError("The 'targets' entry must contain a reference to a node template or group template, '" + target + IS_NONE_OF_THOSE, null);
-                    }
-
-                    if (targetConstruct != null &&
-                            targetsTypes != null) {
-                        //get the target type and make sure is compatible with the types
-                        //indicated in the type spec
-                        String targetType = (String)
-                                this.catalog.getTemplate(theContext.target(), targetConstruct, targetItr).get("type");
-
-                        boolean found = false;
-                        for (String type : targetsTypes) {
-                            found = this.catalog
-                                    .isDerivedFrom(targetConstruct, targetType, type);
-                            if (found) {
-                                break;
-                            }
-                        }
-
-                        if (!found) {
-                            theContext.addError("The 'targets' " + targetConstruct + " entry '" + targetItr + "' is not type compatible with any of types specified in policy type targets", null);
-                        }
-                    }
-                }
-            }
-
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    @Checks(path = "/topology_template/node_templates")
-    protected void check_node_templates(Map<String, Map> theTemplates,
-                                        CheckContext theContext) {
-        theContext.enter("node_templates");
-        try {
-            if (!checkDefinition("node_templates", theTemplates, theContext)) {
-                return;
-            }
-
-            for (Iterator<Map.Entry<String, Map>> i = theTemplates.entrySet().iterator(); i.hasNext(); ) {
-                Map.Entry<String, Map> e = i.next();
-                checkNodeTemplateDefinition(e.getKey(), e.getValue(), theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    /* */
-    private void checkNodeTemplateDefinition(String theName,
-                                             Map theNode,
-                                             CheckContext theContext) {
-        theContext.enter(theName, Construct.Node);
-
-        try {
-            if (!checkDefinition(theName, theNode, theContext)) {
-                return;
-            }
-
-            if (!checkType(Construct.Node, theNode, theContext)) {
-                return;
-            }
-
-            //copy
-            String copy = (String) theNode.get("copy");
-            if (copy != null) {
-                if (!checkTemplateReference(Construct.Node, theContext, copy)) {
-                    theContext.addError("The 'copy' reference " + copy + " does not point to a known node template", null);
-                } else {
-                    //the 'copy' node specification should be used to provide 'defaults'
-                    //for this specification
-                }
-            }
-
-      /* check that we operate on properties and attributes within the scope of
-        the specified node type */
-            if (!checkFacet(
-                    Construct.Node, /*theName,*/theNode, Facet.properties, theContext)) {
-                return;
-            }
-
-            if (!checkFacet(
-                    Construct.Node, /*theName,*/theNode, Facet.attributes, theContext)) {
-                return;
-            }
-
-            //requirement assignment seq
-            if (theNode.containsKey(REQUIREMENTS)) {
-                checkRequirementsAssignmentDefinition(
-                        (List<Map>) theNode.get(REQUIREMENTS), theContext);
-            }
-
-            //capability assignment map: subject to augmentation
-            if (theNode.containsKey(CAPABILITIES)) {
-                checkCapabilitiesAssignmentDefinition(
-                        (Map<String, Map>) theNode.get(CAPABILITIES), theContext);
-            }
-
-            //interfaces
-            if (theNode.containsKey(INTERFACES)) {
-                checkTemplateInterfacesDefinition(
-                        (Map<String, Map>) theNode.get(INTERFACES), theContext);
-            }
-
-            //artifacts: artifacts do not have different definition forms/syntax
-            //depending on the context (type or template) but they are still subject
-            //to 'augmentation'
-            if (theNode.containsKey(ARTIFACTS)) {
-                check_template_artifacts_definition(
-                        (Map<String, Object>) theNode.get(ARTIFACTS), theContext);
-            }
-
-            /* node_filter: the context to which the node filter is applied is very
-             * wide here as opposed to the node filter specification in a requirement
-             * assignment which has a more strict context (target node/capability are
-             * specified).
-             * We could check that there are nodes in this template having the
-             * properties/capabilities specified in this filter, i.e. the filter has
-             * a chance to succeed.
-             */
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    @Checks(path = "/topology_template/relationship_templates")
-    protected void check_relationship_templates(Map theTemplates,
-                                                CheckContext theContext) {
-        theContext.enter("relationship_templates");
-
-        for (Iterator<Map.Entry<String, Map>> i = theTemplates.entrySet().iterator(); i.hasNext(); ) {
-            Map.Entry<String, Map> e = i.next();
-            checkRelationshipTemplateDefinition(e.getKey(), e.getValue(), theContext);
-        }
-        theContext.exit();
-    }
-
-    private void checkRelationshipTemplateDefinition(
-            String theName,
-            Map theRelationship,
-            CheckContext theContext) {
-        theContext.enter(theName, Construct.Relationship);
-        try {
-            if (!checkDefinition(theName, theRelationship, theContext)) {
-                return;
-            }
-
-            if (!checkType(Construct.Relationship, theRelationship, theContext)) {
-                return;
-            }
-
-      /* check that we operate on properties and attributes within the scope of
-        the specified relationship type */
-            if (!checkFacet(Construct.Relationship, theRelationship,
-                    Facet.properties, theContext)) {
-                return;
-            }
-
-            if (!checkFacet(Construct.Relationship, theRelationship,
-                    Facet.attributes, theContext)) {
-                return;
-            }
-
-    /* interface definitions
-           note: augmentation is allowed here so not clear what to check ..
-             maybe report augmentations if so configured .. */
-
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    //requirements and capabilities assignment appear in a node templates
-    private void checkRequirementsAssignmentDefinition(
-            List<Map> theRequirements, CheckContext theContext) {
-        theContext.enter(REQUIREMENTS);
-        try {
-            if (!checkDefinition(REQUIREMENTS, theRequirements, theContext)) {
-                return;
-            }
-
-            //the node type for the node template enclosing these requirements
-            String nodeType = (String) catalog.getTemplate(
-                    theContext.target(),
-                    Construct.Node,
-                    theContext.enclosingConstruct(Construct.Node))
-                    .get("type");
-
-            for (Iterator<Map> ri = theRequirements.iterator(); ri.hasNext(); ) {
-                Map<String, Map> requirement = (Map<String, Map>) ri.next();
-
-                Iterator<Map.Entry<String, Map>> rai = requirement.entrySet().iterator();
-
-                Map.Entry<String, Map> requirementEntry = rai.next();
-                assert !rai.hasNext();
-
-                String requirementName = requirementEntry.getKey();
-                Map requirementDef = findNodeTypeRequirementByName(
-                        nodeType, requirementName);
-
-                if (requirementDef == null) {
-                    theContext.addError("No requirement " + requirementName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
-                    continue;
-                }
-
-                checkRequirementAssignmentDefinition(
-                        requirementName, requirementEntry.getValue(), requirementDef, theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkRequirementAssignmentDefinition(
-            String theRequirementName,
-            Map theAssignment,
-            Map theDefinition,
-            CheckContext theContext) {
-        theContext//.enter("requirement_assignment")
-                .enter(theRequirementName, Construct.Requirement);
-
-        //grab the node type definition to verify compatibility
-
-        try {
-            //node assignment
-            boolean targetNodeIsTemplate = false;
-            String targetNode = (String) theAssignment.get("node");
-            if (targetNode == null) {
-                targetNode = (String) theDefinition.get("node");
-                //targetNodeIsTemplate stays false, targetNode must be a type
-            } else {
-                //the value must be a node template or a node type
-                targetNodeIsTemplate = isTemplateReference(
-                        Construct.Node, theContext, targetNode);
-                if ((!targetNodeIsTemplate) && (!isTypeReference(Construct.Node, targetNode))){
-                        theContext.addError("The 'node' entry must contain a reference to a node template or node type, '" + targetNode + IS_NONE_OF_THOSE, null);
-                        return;
-                    }
-
-                //additional checks
-                String targetNodeDef = (String) theDefinition.get("node");
-                if (targetNodeDef != null && targetNode != null) {
-                    if (targetNodeIsTemplate) {
-                        //if the target is node template, it must be compatible with the
-                        //node type specification in the requirement defintion
-                        String targetNodeType = (String)
-                                catalog.getTemplate(theContext.target(), Construct.Node, targetNode).get("type");
-                        if (!catalog.isDerivedFrom(
-                                Construct.Node, targetNodeType, targetNodeDef)) {
-                            theContext.addError("The required target node type '" + targetNodeType + "' of target node " + targetNode + " is not compatible with the target node type found in the requirement definition: " + targetNodeDef, null);
-                            return;
-                        }
-                    } else {
-                        //if the target is a node type it must be compatible (= or derived
-                        //from) with the node type specification in the requirement definition
-                        if (!catalog.isDerivedFrom(
-                                Construct.Node, targetNode, targetNodeDef)) {
-                            theContext.addError("The required target node type '" + targetNode + "' is not compatible with the target node type found in the requirement definition: " + targetNodeDef, null);
-                            return;
-                        }
-                    }
-                }
-            }
-
-            String targetNodeType = targetNodeIsTemplate ?
-                    (String) catalog.getTemplate(theContext.target(), Construct.Node, targetNode).get("type") :
-                    targetNode;
-
-            //capability assignment
-            boolean targetCapabilityIsType = false;
-            String targetCapability = (String) theAssignment.get(CAPABILITY);
-            if (targetCapability == null) {
-                targetCapability = (String) theDefinition.get(CAPABILITY);
-                //in a requirement definition the target capability can only be a
-                //capability type (and not a capability name within some target node
-                //type)
-                targetCapabilityIsType = true;
-            } else {
-                targetCapabilityIsType = isTypeReference(Construct.Capability, targetCapability);
-
-                //check compatibility with the target compatibility type specified
-                //in the requirement definition, if any
-                String targetCapabilityDef = (String) theDefinition.get(CAPABILITY);
-                if (targetCapabilityDef != null && targetCapability != null) {
-                    if (targetCapabilityIsType) {
-                        if (!catalog.isDerivedFrom(
-                                Construct.Capability, targetCapability, targetCapabilityDef)) {
-                            theContext.addError("The required target capability type '" + targetCapability + "' is not compatible with the target capability type found in the requirement definition: " + targetCapabilityDef, null);
-                            return;
-                        }
-                    } else {
-                        //the capability is from a target node. Find its definition and
-                        //check that its type is compatible with the capability type
-                        //from the requirement definition
-
-                        //check target capability compatibility with target node
-                        if (targetNode == null) {
-                            theContext.addError("The capability '" + targetCapability + "' is not a capability type, hence it has to be a capability of the node template indicated in 'node', which was not specified", null);
-                            return;
-                        }
-                        if (!targetNodeIsTemplate) {
-                            theContext.addError("The capability '" + targetCapability + "' is not a capability type, hence it has to be a capability of the node template indicated in 'node', but there you specified a node type", null);
-                            return;
-                        }
-                        //check that the targetNode (its type) indeed has the
-                        //targetCapability
-
-                        Map<String, Object> targetNodeCapabilityDef =
-                                findTypeFacetByName(
-                                        Construct.Node, targetNodeType,
-                                        Facet.capabilities, targetCapability);
-                        if (targetNodeCapabilityDef == null) {
-                            theContext.addError("No capability '" + targetCapability + "' was specified in the node " + targetNode + " of type " + targetNodeType, null);
-                            return;
-                        }
-
-                        String targetNodeCapabilityType = (String) targetNodeCapabilityDef.get("type");
-
-                        if (!catalog.isDerivedFrom(Construct.Capability,
-                                targetNodeCapabilityType,
-                                targetCapabilityDef)) {
-                            theContext.addError("The required target capability type '" + targetCapabilityDef + "' is not compatible with the target capability type found in the target node type capability definition : " + targetNodeCapabilityType + ", targetNode " + targetNode + ", capability name " + targetCapability, null);
-                            return;
-                        }
-                    }
-                }
-            }
-
-            //relationship assignment
-            Map targetRelationship = (Map) theAssignment.get("relationship");
-            if (targetRelationship != null) {
-                //this has to be compatible with the relationship with the same name
-                //from the node type
-                //check the type
-            }
-
-            //node_filter; used jxpath to simplify the navigation somewhat
-            //this is too cryptic
-            JXPathContext jxPath = JXPathContext.newContext(theAssignment);
-            jxPath.setLenient(true);
-
-            List<Map> propertiesFilter =
-                    (List<Map>) jxPath.getValue("/node_filter/properties");
-            if (propertiesFilter != null) {
-                for (Map propertyFilter : propertiesFilter) {
-                    if (targetNode != null) {
-                        //if we have a target node or node template then it must have
-                        //have these properties
-                        for (Object propertyName : propertyFilter.keySet()) {
-                            if (null == findTypeFacetByName(Construct.Node,
-                                    targetNodeType,
-                                    Facet.properties,
-                                    propertyName.toString())) {
-                                theContext.addError("The node_filter property " + propertyName + " is invalid: requirement target node " + targetNode + " does not have such a property", null);
-                            }
-                        }
-                    }
-                }
-            }
-
-            List<Map> capabilitiesFilter =
-                    (List<Map>) jxPath.getValue("node_filter/capabilities");
-            if (capabilitiesFilter != null) {
-                for (Map capabilityFilterDef : capabilitiesFilter) {
-                    assert capabilityFilterDef.size() == 1;
-                    Map.Entry<String, Map> capabilityFilterEntry =
-                            (Map.Entry<String, Map>) capabilityFilterDef.entrySet().iterator().next();
-                    String targetFilterCapability = capabilityFilterEntry.getKey();
-                    Map<String, Object> targetFilterCapabilityDef = null;
-
-                    //if we have a targetNode capabilityName must be a capability of
-                    //that node (type); or it can be simply capability type (but the node
-                    //must have a capability of that type)
-
-                    String targetFilterCapabilityType = null;
-                    if (targetNode != null) {
-                        targetFilterCapabilityDef =
-                                findTypeFacetByName(Construct.Node, targetNodeType,
-                                        Facet.capabilities, targetFilterCapability);
-                        if (targetFilterCapabilityDef != null) {
-                            targetFilterCapabilityType =
-                                    (String) targetFilterCapabilityDef/*.values().iterator().next()*/.get("type");
-                        } else {
-                            Map<String, Map> targetFilterCapabilities =
-                                    findTypeFacetByType(Construct.Node, targetNodeType,
-                                            Facet.capabilities, targetFilterCapability);
-
-                            if (!targetFilterCapabilities.isEmpty()) {
-                                if (targetFilterCapabilities.size() > 1) {
-                                    errLogger.log(LogLevel.WARN, this.getClass().getName(), "checkRequirementAssignmentDefinition: filter check, target node type '{}' has more than one capability of type '{}', not supported", targetNodeType, targetFilterCapability);
-                                }
-                                //pick the first entry, it represents a capability of the required type
-                                Map.Entry<String, Map> capabilityEntry = targetFilterCapabilities.entrySet().iterator().next();
-                                targetFilterCapabilityDef = Collections.singletonMap(capabilityEntry.getKey(),
-                                        capabilityEntry.getValue());
-                                targetFilterCapabilityType = targetFilterCapability;
-                            }
-                        }
-                    } else {
-                        //no node (type) specified, it can be a straight capability type
-                        targetFilterCapabilityDef = catalog.getTypeDefinition(
-                                Construct.Capability, targetFilterCapability);
-                        //here comes the odd part: it can still be a just a name in which
-                        //case we should look at the requirement definition, see which
-                        //capability (type) it indicates
-                        assert targetCapabilityIsType; //cannot be otherwise, we'd need a node
-                        targetFilterCapabilityDef = catalog.getTypeDefinition(
-                                Construct.Capability, targetCapability);
-                        targetFilterCapabilityType = targetCapability;
-                    }
-
-                    if (targetFilterCapabilityDef == null) {
-                        theContext.addError("Capability (name or type) " + targetFilterCapability + " is invalid: not a known capability (type) " +
-                                ((targetNodeType != null) ? (" of node type" + targetNodeType) : ""), null);
-                        continue;
-                    }
-
-                    for (Map propertyFilter :
-                            (List<Map>) jxPath.getValue("/node_filter/capabilities/" + targetFilterCapability + "/properties")) {
-                        //check that the properties are in the scope of the
-                        //capability definition
-                        for (Object propertyName : propertyFilter.keySet()) {
-                            if (null == findTypeFacetByName(Construct.Capability,
-                                    targetCapability,
-                                    Facet.properties,
-                                    propertyName.toString())) {
-                                theContext.addError("The capability filter " + targetFilterCapability + " property " + propertyName + " is invalid: target capability " + targetFilterCapabilityType + " does not have such a property", null);
-                            }
-                        }
-                    }
-                }
-            }
-
-        } finally {
-            theContext//.exit()
-                    .exit();
-        }
-    }
-
-    private void checkCapabilitiesAssignmentDefinition(
-            Map<String, Map> theCapabilities, CheckContext theContext) {
-        theContext.enter(CAPABILITIES);
-        try {
-            if (!checkDefinition(CAPABILITIES, theCapabilities, theContext)) {
-                return;
-            }
-
-            //the node type for the node template enclosing these requirements
-            String nodeType = (String) catalog.getTemplate(
-                    theContext.target(),
-                    Construct.Node,
-                    theContext.enclosingConstruct(Construct.Node))
-                    .get("type");
-
-            for (Iterator<Map.Entry<String, Map>> ci =
-                 theCapabilities.entrySet().iterator();
-                 ci.hasNext(); ) {
-
-                Map.Entry<String, Map> ce = ci.next();
-
-                String capabilityName = ce.getKey();
-                Map capabilityDef = findTypeFacetByName(Construct.Node, nodeType,
-                        Facet.capabilities, capabilityName);
-                if (capabilityDef == null) {
-                    theContext.addError("No capability " + capabilityName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
-                    continue;
-                }
-
-                checkCapabilityAssignmentDefinition(
-                        capabilityName, ce.getValue(), capabilityDef, theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkCapabilityAssignmentDefinition(
-            String theCapabilityName,
-            Map theAssignment,
-            Map theDefinition,
-            CheckContext theContext) {
-
-        theContext.enter(theCapabilityName, Construct.Capability);
-        try {
-            String capabilityType = (String) theDefinition.get("type");
-            //list of property and attributes assignments
-            checkFacet(Construct.Capability, theAssignment, capabilityType,
-                    Facet.properties, theContext);
-            checkFacet(Construct.Capability, theAssignment, capabilityType,
-                    Facet.attributes, theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkTemplateInterfacesDefinition(
-            Map<String, Map> theInterfaces,
-            CheckContext theContext) {
-        theContext.enter(INTERFACES);
-        try {
-            if (!checkDefinition(INTERFACES, theInterfaces, theContext)) {
-                return;
-            }
-
-            //the node type for the node template enclosing these requirements
-            String nodeType = (String) catalog.getTemplate(
-                    theContext.target(),
-                    Construct.Node,
-                    theContext.enclosingConstruct(Construct.Node))
-                    .get("type");
-
-            for (Iterator<Map.Entry<String, Map>> ii =
-                 theInterfaces.entrySet().iterator();
-                 ii.hasNext(); ) {
-
-                Map.Entry<String, Map> ie = ii.next();
-
-                String interfaceName = ie.getKey();
-                Map interfaceDef = findTypeFacetByName(Construct.Node, nodeType,
-                        Facet.interfaces, interfaceName);
-
-                if (interfaceDef == null) {
-                    /* this is subject to augmentation: this could be a warning but not an error */
-                    theContext.addError("No interface " + interfaceName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
-                    continue;
-                }
-
-                checkTemplateInterfaceDefinition(
-                        interfaceName, ie.getValue(), interfaceDef, theContext);
-            }
-        } finally {
-            theContext.exit();
-        }
-    }
-
-    private void checkTemplateInterfaceDefinition(
-            String theInterfaceName,
-            Map theAssignment,
-            Map theDefinition,
-            CheckContext theContext) {
-
-        theContext.enter(theInterfaceName, Construct.Interface);
-        try {
-            //check the assignment of the common inputs
-            checkFacet(Construct.Interface,
-                    theAssignment,
-                    (String) theDefinition.get("type"),
-                    Facet.inputs,
-                    theContext);
-        } finally {
-            theContext.exit();
-        }
-    }
-
-
-    @Checks(path = "/topology_template/artifacts")
-    protected void check_template_artifacts_definition(
-            Map<String, Object> theDefinition,
-            CheckContext theContext) {
-        theContext.enter(ARTIFACTS);
-        theContext.exit();
-    }
-
-    //generic checking actions, not related to validation rules
-
-    /* will check the validity of the type specification for any construct containing a 'type' entry */
-    private boolean checkType(Construct theCategory, Map theSpec, CheckContext theContext) {
-        String type = (String) theSpec.get("type");
-        if (type == null) {
-            theContext.addError("Missing type specification", null);
-            return false;
-        }
-
-        if (!catalog.hasType(theCategory, type)) {
-            theContext.addError(UNKNOWN + theCategory + " type: " + type, null);
-            return false;
-        }
-
-        return true;
-    }
-
-    /* the type can be:
-     *   a known type: predefined or user-defined
-     *   a collection (list or map) and then check that the entry_schema points to one of the first two cases (is that it?)
-     */
-    private boolean checkDataType(Map theSpec, CheckContext theContext) {
-
-        if (!checkType(Construct.Data, theSpec, theContext)) {
-            return false;
-        }
-
-        String type = (String) theSpec.get("type");
-        if (/*isCollectionType(type)*/
-                "list".equals(type) || "map".equals(type)) {
-            Map entrySchema = (Map) theSpec.get("entry_schema");
-            if (entrySchema == null) {
-                //maybe issue a warning ?? or is 'string' the default??
-                return true;
-            }
-
-            if (!catalog.hasType(Construct.Data, (String) entrySchema.get("type"))) {
-                theContext.addError("Unknown entry_schema type: " + entrySchema, null);
-                return false;
-            }
-        }
-        return true;
-    }
-
-    /* Check that a particular facet (properties, attributes) of a construct type
-     * (node type, capability type, etc) is correctly (consistenly) defined
-     * across a type hierarchy
-     */
-    private boolean checkTypeConstructFacet(Construct theConstruct,
-                                            String theTypeName,
-                                            Map theTypeSpec,
-                                            Facet theFacet,
-                                            CheckContext theContext) {
-        Map<String, Map> defs =
-                (Map<String, Map>) theTypeSpec.get(theFacet.name());
-        if (null == defs) {
-            return true;
-        }
-
-        boolean res = true;
-
-        //given that the type was cataloged there will be at least one entry
-        Iterator<Map.Entry<String, Map>> i =
-                catalog.hierarchy(theConstruct, theTypeName);
-        if (!i.hasNext()) {
-            theContext.addError(
-                    "The type " + theTypeName + " needs to be cataloged before attempting 'checkTypeConstruct'", null);
-            return false;
-        }
-        i.next(); //skip self
-        while (i.hasNext()) {
-            Map.Entry<String, Map> e = i.next();
-            Map<String, Map> superDefs = (Map<String, Map>) e.getValue()
-                    .get(theFacet.name());
-            if (null == superDefs) {
-                continue;
-            }
-            //this computes entries that appear on both collections but with different values, i.e. the re-defined properties
-            Map<String, MapDifference.ValueDifference<Map>> diff = Maps.difference(defs, superDefs).entriesDiffering();
-
-            for (Iterator<Map.Entry<String, MapDifference.ValueDifference<Map>>> di = diff.entrySet().iterator(); di.hasNext(); ) {
-                Map.Entry<String, MapDifference.ValueDifference<Map>> de = di.next();
-                MapDifference.ValueDifference<Map> dediff = de.getValue();
-                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "{} type {}: {} has been re-defined between the {} types {} and {}", theConstruct, theFacet, de.getKey(), theConstruct, e.getKey(), theTypeName);
-                //for now we just check that the type is consistenly re-declared
-                if (!this.catalog.isDerivedFrom(theFacet.construct(),
-                        (String) dediff.leftValue().get("type"),
-                        (String) dediff.rightValue().get("type"))) {
-                    theContext.addError(
-                            theConstruct + TYPE + theFacet + ", redefiniton changed its type: " + de.getKey() + " has been re-defined between the " + theConstruct + " types " + e.getKey() + " and " + theTypeName + " in an incompatible manner", null);
-                    res = false;
-                }
-            }
-        }
-
-        return res;
-    }
-
-    /*
-     * Checks the validity of a certain facet of a construct
-     * (properties of a node) across a type hierarchy.
-     * For now the check is limited to a verifying that a a facet was declared
-     * somewhere in the construct type hierarchy (a node template property has
-     * been declared in the node type hierarchy).
-     *
-     * 2 versions with the more generic allowing the specification of the type
-     * to be done explicitly.
-     */
-    private boolean checkFacet(Construct theConstruct,
-                               Map theSpec,
-                               Facet theFacet,
-                               CheckContext theContext) {
-        return checkFacet(theConstruct, theSpec, null, theFacet, theContext);
-    }
-
-    /**
-     * We walk the hierarchy and verify the assignment of a property with respect to its definition.
-     * We also collect the names of those properties defined as required but for which no assignment was provided.
-     */
-    private boolean checkFacet(Construct theConstruct,
-                               Map theSpec,
-                               String theSpecType,
-                               Facet theFacet,
-                               CheckContext theContext) {
-
-        Map<String, Map> defs = (Map<String, Map>) theSpec.get(theFacet.name());
-        if (null == defs) {
-            return true;
-        }
-        defs = Maps.newHashMap(defs); //
-
-        boolean res = true;
-        if (theSpecType == null) {
-            theSpecType = (String) theSpec.get("type");
-        }
-        if (theSpecType == null) {
-            theContext.addError("No specification type available", null);
-            return false;
-        }
-
-        Map<String, Byte> missed = new HashMap<>();  //keeps track of the missing required properties, the value is
-        //false if a default was found along the hierarchy
-        Iterator<Map.Entry<String, Map>> i =
-                catalog.hierarchy(theConstruct, theSpecType);
-        while (i.hasNext() && !defs.isEmpty()) {
-            Map.Entry<String, Map> type = i.next();
-
-            Map<String, Map> typeDefs = (Map<String, Map>) type.getValue()
-                    .get(theFacet.name());
-            if (null == typeDefs) {
-                continue;
-            }
-
-            MapDifference<String, Map> diff = Maps.difference(defs, typeDefs);
-
-            //this are the ones this type and the spec have in common (same key,
-            //different values)
-            Map<String, MapDifference.ValueDifference<Map>> facetDefs =
-                    diff.entriesDiffering();
-            //TODO: this assumes the definition of the facet is not cumulative, i.e.
-            //subtypes 'add' something to the definition provided by the super-types
-            //it considers the most specialized definition stands on its own
-            for (MapDifference.ValueDifference<Map> valdef : facetDefs.values()) {
-                checkDataValuation(valdef.leftValue(), valdef.rightValue(), theContext);
-            }
-
-            //remove from properties all those that appear in this type: unfortunately this returns an unmodifiable map ..
-            defs = Maps.newHashMap(diff.entriesOnlyOnLeft());
-        }
-
-        if (!defs.isEmpty()) {
-            theContext.addError(UNKNOWN + theConstruct + " " + theFacet + " (not declared by the type " + theSpecType + ") were used: " + defs, null);
-            res = false;
-        }
-
-        if (!missed.isEmpty()) {
-            List missedNames =
-                    missed.entrySet()
-                            .stream()
-                            .filter(e -> e.getValue().byteValue() == (byte) 1)
-                            .map(e -> e.getKey())
-                            .collect(Collectors.toList());
-            if (!missedNames.isEmpty()) {
-                theContext.addError(theConstruct + " " + theFacet + " missing required values for: " + missedNames, null);
-                res = false;
-            }
-        }
-
-        return res;
-    }
-
-    /* Augmentation occurs in cases such as the declaration of capabilities within a node type.
-     * In such cases the construct facets (the capabilitity's properties) can redefine (augment) the
-     * specification found in the construct type.
-     */
-    private boolean checkFacetAugmentation(Construct theConstruct,
-                                           Map theSpec,
-                                           Facet theFacet,
-                                           CheckContext theContext) {
-        return checkFacetAugmentation(theConstruct, theSpec, null, theFacet, theContext);
-    }
-
-    private boolean checkFacetAugmentation(Construct theConstruct,
-                                           Map theSpec,
-                                           String theSpecType,
-                                           Facet theFacet,
-                                           CheckContext theContext) {
-
-        Map<String, Map> augs = (Map<String, Map>) theSpec.get(theFacet.name());
-        if (null == augs) {
-            return true;
-        }
-
-        boolean res = true;
-        if (theSpecType == null) {
-            theSpecType = (String) theSpec.get("type");
-        }
-        if (theSpecType == null) {
-            theContext.addError("No specification type available", null);
-            return false;
-        }
-
-        for (Map.Entry<String, Map> ae : augs.entrySet()) {
-            //make sure it was declared by the type
-            Map facetDef = catalog.getFacetDefinition(theConstruct, theSpecType, theFacet, ae.getKey());
-            if (facetDef == null) {
-                theContext.addError(UNKNOWN + theConstruct + " " + theFacet + " (not declared by the type " + theSpecType + ") were used: " + ae.getKey(), null);
-                res = false;
-                continue;
-            }
-
-            //check the compatibility of the augmentation: only the type cannot be changed
-            //can the type be changed in a compatible manner ??
-            if (!facetDef.get("type").equals(ae.getValue().get("type"))) {
-                theContext.addError(theConstruct + " " + theFacet + " " + ae.getKey() + " has a different type than its definition: " + ae.getValue().get("type") + " instead of " + facetDef.get("type"), null);
-                res = false;
-                continue;
-            }
-
-            //check any valuation (here just defaults)
-            Object defaultValue = ae.getValue().get(DEFAULT);
-            if (defaultValue != null) {
-                checkDataValuation(defaultValue, ae.getValue(), theContext);
-            }
-        }
-
-        return res;
-    }
-
-    private boolean catalogTypes(Construct theConstruct, Map<String, Map> theTypes, CheckContext theContext) {
-
-        boolean res = true;
-        for (Map.Entry<String, Map> typeEntry : theTypes.entrySet()) {
-            res &= catalogType(theConstruct, typeEntry.getKey(), typeEntry.getValue(), theContext);
-        }
-
-        return res;
-    }
-
-    private boolean catalogType(Construct theConstruct,
-                                String theName,
-                                Map theDef,
-                                CheckContext theContext) {
-
-        if (!catalog.addType(theConstruct, theName, theDef)) {
-            theContext.addError(theConstruct + TYPE + theName + " re-declaration", null);
-            return false;
-        }
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "{} type {} has been cataloged", theConstruct, theName);
-
-        String parentType = (String) theDef.get("derived_from");
-        if (parentType != null && !catalog.hasType(theConstruct, parentType)) {
-            theContext.addError(
-                    theConstruct + TYPE + theName + " indicates a supertype that has not (yet) been declared: " + parentType, null);
-            return false;
-        }
-        return true;
-    }
-
-    private boolean checkTypeReference(Construct theConstruct,
-                                       CheckContext theContext,
-                                       String... theTypeNames) {
-        boolean res = true;
-        for (String typeName : theTypeNames) {
-            if (!isTypeReference(theConstruct, typeName)) {
-                theContext.addError("Reference to " + theConstruct + " type '" + typeName + "' points to unknown type", null);
-                res = false;
-            }
-        }
-        return res;
-    }
-
-    private boolean isTypeReference(Construct theConstruct,
-                                    String theTypeName) {
-        return this.catalog.hasType(theConstruct, theTypeName);
-    }
-
-    /* node or relationship templates */
-    private boolean checkTemplateReference(Construct theConstruct,
-                                           CheckContext theContext,
-                                           String... theTemplateNames) {
-        boolean res = true;
-        for (String templateName : theTemplateNames) {
-            if (!isTemplateReference(theConstruct, theContext, templateName)) {
-                theContext.addError("Reference to " + theConstruct + " template '" + templateName + "' points to unknown template", null);
-                res = false;
-            }
-        }
-        return res;
-    }
-
-    private boolean isTemplateReference(Construct theConstruct,
-                                        CheckContext theContext,
-                                        String theTemplateName) {
-        return this.catalog.hasTemplate(theContext.target(), theConstruct, theTemplateName);
-    }
-
-    /*
-     * For inputs/properties/attributes/(parameters). It is the caller's
-     * responsability to provide the value (from a 'default', inlined, ..)
-     *
-     * @param theDef the definition of the given construct/facet as it appears in
-     * 			its enclosing type definition.
-     * @param
-     */
-    private boolean checkDataValuation(Object theExpr,
-                                       Map<String, ?> theDef,
-                                       CheckContext theContext) {
-        //first check if the expression is a function, if not handle it as a value assignment
-        Data.Function f = Data.function(theExpr);
-        if (f != null) {
-            return f.evaluator()
-                    .eval(theExpr, theDef, theContext);
-        } else {
-            Data.Type type = Data.typeByName((String) theDef.get("type"));
-            if (type != null) {
-                Data.Evaluator evaluator;
-
-                evaluator = type.evaluator();
-                if (evaluator == null) {
-                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "No value evaluator available for type {}", type);
-                } else {
-                    if ((theExpr != null) && (!evaluator.eval(theExpr, theDef, theContext))) {
-                        return false;
-                    }
-                }
-
-
-                evaluator = type.constraintsEvaluator();
-                if (evaluator == null) {
-                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "No constraints evaluator available for type {}", type);
-                } else {
-                    if (theExpr != null) {
-                        if (!evaluator.eval(theExpr, theDef, theContext)) {
-                            return false;
-                        }
-                    } else {
-                        //should have a null value validatorT
-                    }
-                }
-
-                return true;
-            } else {
-                theContext.addError("Expression " + theExpr + " of " + theDef + " could not be evaluated", null);
-                return false;
-            }
-        }
-    }
-
-    /**
-     * Given the type of a certain construct (node type for example), look up
-     * in one of its facets (properties, capabilities, ..) for one of the given
-     * facet type (if looking in property, one of the given data type).
-     *
-     * @return a map of all facets of the given type, will be empty to signal
-     * none found
-     * <p>
-     * Should we look for a facet construct of a compatible type: any type derived
-     * from the given facet's construct type??
-     */
-    private Map<String, Map>
-    findTypeFacetByType(Construct theTypeConstruct,
-                        String theTypeName,
-                        Facet theFacet,
-                        String theFacetType) {
-
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType {}, {}: {} {}", theTypeName, theTypeConstruct, theFacetType, theFacet);
-        Map<String, Map> res = new HashMap<>();
-        Iterator<Map.Entry<String, Map>> i =
-                catalog.hierarchy(theTypeConstruct, theTypeName);
-        while (i.hasNext()) {
-            Map.Entry<String, Map> typeSpec = i.next();
-            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, Checking {} type {}", theTypeConstruct, typeSpec.getKey());
-            Map<String, Map> typeFacet =
-                    (Map<String, Map>) typeSpec.getValue().get(theFacet.name());
-            if (typeFacet == null) {
-                continue;
-            }
-            Iterator<Map.Entry<String, Map>> fi = typeFacet.entrySet().iterator();
-            while (fi.hasNext()) {
-                Map.Entry<String, Map> facet = fi.next();
-                String facetType = (String) facet.getValue().get("type");
-                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, Checking {} type {}", facet.getKey(), facetType);
-
-                //here is the question: do we look for an exact match or ..
-                //now we check that the type has a capability of a type compatible
-                //(equal or derived from) the given capability type.
-                if (catalog.isDerivedFrom(
-                        theFacet.construct(), facetType, theFacetType)) {
-                    res.putIfAbsent(facet.getKey(), facet.getValue());
-                }
-            }
-        }
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, found {}", res);
-
-        return res;
-    }
-
-    private Map<String, Object>
-    findTypeFacetByName(Construct theTypeConstruct,
-                        String theTypeName,
-                        Facet theFacet,
-                        String theFacetName) {
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByName {} {}", theTypeConstruct, theTypeName);
-        Iterator<Map.Entry<String, Map>> i =
-                catalog.hierarchy(theTypeConstruct, theTypeName);
-        while (i.hasNext()) {
-            Map.Entry<String, Map> typeSpec = i.next();
-            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByName, Checking {} type {}", theTypeConstruct, typeSpec.getKey());
-            Map<String, Map> typeFacet =
-                    (Map<String, Map>) typeSpec.getValue().get(theFacet.name());
-            if (typeFacet == null) {
-                continue;
-            }
-            Map<String, Object> facet = typeFacet.get(theFacetName);
-            if (facet != null) {
-                return facet;
-            }
-        }
-        return null;
-    }
-
-    /* Requirements are the odd ball as they are structured as a sequence .. */
-    private Map<String, Map> findNodeTypeRequirementByName(
-            String theNodeType, String theRequirementName) {
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findNodeTypeRequirementByName {}/{}", theNodeType, theRequirementName);
-        Iterator<Map.Entry<String, Map>> i =
-                catalog.hierarchy(Construct.Node, theNodeType);
-        while (i.hasNext()) {
-            Map.Entry<String, Map> nodeType = i.next();
-            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findNodeTypeRequirementByName, Checking node type {}", nodeType.getKey());
-            List<Map<String, Map>> nodeTypeRequirements =
-                    (List<Map<String, Map>>) nodeType.getValue().get(REQUIREMENTS);
-            if (nodeTypeRequirements == null) {
-                continue;
-            }
-
-            for (Map<String, Map> requirement : nodeTypeRequirements) {
-                Map requirementDef = requirement.get(theRequirementName);
-                if (requirementDef != null) {
-                    return requirementDef;
-                }
-            }
-        }
-        return null;
-    }
-
     /*
      * Additional generics checks to be performed on any definition: construct,
      * construct types, etc ..
      */
-    public boolean checkDefinition(String theName,
-                                   Map theDefinition,
-                                   CheckContext theContext) {
-        if (theDefinition == null) {
-            theContext.addError("Missing definition for " + theName, null);
-            return false;
-        }
-
-        if (theDefinition.isEmpty()) {
-            theContext.addError("Empty definition for " + theName, null);
-            return false;
-        }
-
-        return true;
-    }
 
-    private boolean checkDefinition(String theName,
-                                    List theDefinition,
-                                    CheckContext theContext) {
-        if (theDefinition == null) {
-            theContext.addError("Missing definition for " + theName, null);
-            return false;
-        }
-
-        if (theDefinition.isEmpty()) {
-            theContext.addError("Empty definition for " + theName, null);
-            return false;
-        }
-
-        return true;
-    }
 
     /* plenty of one entry maps around */
     private Map.Entry mapEntry(Object theMap) {
@@ -2715,16 +609,16 @@ public class Checker {
     private String patchWhitespaces(String thePath) {
         String[] elems = thePath.split("/");
         StringBuilder path = new StringBuilder();
-        for (int i = 0; i < elems.length; i++) {
-            if (spacePattern.matcher(elems[i]).find()) {
+        Arrays.stream(elems).forEach(elem -> {
+            if (spacePattern.matcher(elem).find()) {
                 path.append("[@name='")
-                        .append(elems[i])
+                        .append(elem)
                         .append("']");
             } else {
                 path.append("/")
-                        .append(elems[i]);
+                        .append(elem);
             }
-        }
+        });
         return path.toString();
     }
 
@@ -2816,66 +710,23 @@ public class Checker {
         Catalog catalog = new Catalog(doCommons ? commonsCatalog() : null);
         if (!doCommons) {
             //add core TOSCA types
-            for (Data.CoreType type : Data.CoreType.class.getEnumConstants()) {
-                catalog.addType(Construct.Data, type.toString(), Collections.emptyMap());
-            }
+            Arrays.stream(Data.CoreType.class.getEnumConstants()).forEach(type -> catalog.addType(Construct.Data, type.toString(), Collections.emptyMap()));
         }
         return catalog;
     }
 
-    private boolean invokeHook(String theHookName,
-                               Class[] theArgTypes,
-                               Object... theArgs) {
-
-        Invokable hookHandler = null;
-        try {
-            Method m = Checker.class.getDeclaredMethod(
-                    theHookName, theArgTypes);
-            m.setAccessible(true);
-            hookHandler = Invokable.from(m);
-        } catch (NoSuchMethodException nsmx) {
-            //that's ok, not every rule has to have a handler
-            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), getClass().getName(), "That's ok, not every rule has to have a handler. Method name is:{}. Exception:{}", theHookName,nsmx);
-        }
-
-        if (hookHandler != null) {
-            try {
-                hookHandler.invoke(this, theArgs);
-            } catch (InvocationTargetException | IllegalAccessException itx) {
-                errLogger.log(LogLevel.WARN, this.getClass().getName(), "Invocation failed for hook handler {} {}", theHookName, itx);
-            } catch (Exception x) {
-                errLogger.log(LogLevel.WARN, this.getClass().getName(), "Hook handler failed {} {}", theHookName, x);
-            }
-        }
-
-        return hookHandler != null;
-    }
-
-    private void validationHook(String theTiming,
-                                Object theTarget,
-                                Rule theRule,
-                                Validator.ValidationContext theContext) {
-
-        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "looking up validation handler for {}, {} {}", theRule.getName(), theTiming, theContext.getPath());
-        if (!invokeHook(theRule.getName() + "_" + theTiming + "_validation_handler",
-                validationHookArgTypes,
-                theTarget, theRule, theContext)) {
-            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "no validation handler for {}", theRule.getName() + "_" + theTiming);
-        }
-    }
-
     private void checks(String theName,
                         Object theTarget,
                         CheckContext theContext) {
         Map<Method, Object> handlers = checks.row(/*theName*/theContext.getPath(theName));
         if (handlers != null) {
-            for (Map.Entry<Method, Object> handler : handlers.entrySet()) {
+            handlers.entrySet().forEach(handler -> {
                 try {
                     handler.getKey().invoke(handler.getValue(), new Object[]{theTarget, theContext});
                 } catch (Exception x) {
                     errLogger.log(LogLevel.WARN, this.getClass().getName(), "Check {} with {} failed {}", theName, handler.getKey(), x);
                 }
-            }
+            });
         } else {
             boolean hasHook = false;
             for (Class[] argTypes : checkHookArgTypes) {
@@ -2897,112 +748,25 @@ public class Checker {
 
         Map<Method, Object> handlers = catalogs.row(/*theName*/theContext.getPath(theName));
         if (handlers != null) {
-            for (Map.Entry<Method, Object> handler : handlers.entrySet()) {
+            handlers.forEach((key, value) -> {
                 try {
-                    handler.getKey().invoke(handler.getValue(), new Object[]{theTarget, theContext});
+                    key.invoke(value, theTarget, theContext);
                 } catch (Exception x) {
-                    errLogger.log(LogLevel.WARN, this.getClass().getName(), "Cataloging {} with {} failed {}", theName, handler.getKey(), x);
+                    errLogger.log(LogLevel.WARN, this.getClass().getName(), "Cataloging {} with {} failed {}", theName, key, x);
                 }
-            }
+            });
         }
     }
 
-    private class TOSCAValidator extends Validator {
-
-        //what were validating
-        private Target target;
-
-    /* Some of the TOSCA entries accept a 'short form/notation' instead of the canonical map representation.
-     * kwalify cannot easily express these alternatives and as such we handle them here. In the pre-validation phase we detect the presence of a short notation 
-and compute the canonical form and validate it. In the post-validation phase we
-substitute the canonical form for the short form so that checking does not have to deal with it. 
-     */
-
-        private Map<String, Object> canonicals = new TreeMap<>();
-
-        TOSCAValidator(Target theTarget, Object theSchema) {
-            super(theSchema);
-            this.target = theTarget;
-        }
-
-        public Target getTarget() {
-            return this.target;
-        }
-
-        /* hook method called by Validator#validate()
-         */
-        @Override
-        protected boolean preValidationHook(Object value, Rule rule, ValidationContext context) {
-
-            validationHook("pre", value, rule, context);
-            //short form handling
-            String hint = rule.getShort();
-            if (value != null &&
-                    hint != null) {
-
-                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Attempting canonical at {}, rule {}", context.getPath(), rule.getName());
-
-                Object canonical = null;
-                //if the canonical form requires a collection
-                if (Types.isCollectionType(rule.getType())) {
-                    //and the actual value isn't one
-                    if (!(value instanceof Map || value instanceof List)) {
-                        //used to use singleton map/list here (was good for catching errors)
-                        //but there is the possibility if short forms within short forms so
-                        //the created canonicals need to accomodate other values.
-                        if (Types.isMapType(rule.getType())) {
-                            canonical = new HashMap();
-                            ((Map) canonical).put(hint, value);
-                        } else {
-                            //the hint is irrelevant here but we should impose a value when the target is a list
-                            canonical = new LinkedList();
-                            ((List) canonical).add(value);
-                        }
-                    } else {
-                        //we can accomodate:
-                        // map to list of map transformation
-                        if (!Types.isMapType(rule.getType()) /* a seq */ &&
-                                value instanceof Map) {
-                            canonical = new LinkedList();
-                            ((List) canonical).add(value);
-                        } else {
-                            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Grammar for rule {} (at {}) would require unsupported short form transformation: {} to {}", rule.getName(), context.getPath(), value.getClass(), rule.getType());
-                            return false;
-                        }
-                    }
-
-                    int errc = context.errorCount();
-                    validateRule(canonical, rule, context);
-                    if (errc != context.errorCount()) {
-                        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Short notation for {} through {} at {} failed validation", rule.getName(), hint, context.getPath());
-                    } else {
-                        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Short notation for {} through {} at {} passed validation. Canonical form is {}", rule.getName(), hint, context.getPath(), canonical);
-                        //replace the short notation with the canonicall one so we don't
-                        //have to deal it again during checking
-                        this.canonicals.put(context.getPath(), canonical);
-                        return true;
-                    }
-                } else {
-                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Grammar for rule {} (at {}) would require unsupported short form transformation: {} to {}", rule.getName(), context.getPath(), value.getClass(), rule.getType());
-                }
-            }
-
-            //perform default validation process
-            return false;
-        }
-
-        /*
-         * Only gets invoked once the value was succesfully verified against the syntax indicated by the given rule.
-         */
-        @Override
-        protected void postValidationHook(Object value,
-                                          Rule rule,
-                                          ValidationContext context) {
-            validationHook("post", value, rule, context);
-        }
+    public boolean checkDefinition(String workflows, Map theDefinition, CheckContext theContext) {
+        return  checkCommon.checkDefinition(workflows, theDefinition, theContext);
+    }
 
+    public void checkProperties(Map<String, Map> inputs, CheckContext theContext) {
+        propertiesCommon.checkProperties(inputs, theContext, catalog);
     }
 
+
     /**
      * Maintains state across the checking process.
      */
@@ -3093,23 +857,20 @@ substitute the canonical form for the short form so that checking does not have
     
 	private String errorReport(List<Throwable> theErrors) {
 		StringBuilder sb = new StringBuilder(theErrors.size() + " errors");
-		for (Throwable x : theErrors) {
-			sb.append("\n");
-			if (x instanceof ValidationException) {
-				ValidationException vx = (ValidationException) x;
-				// .apend("at ")
-				// .append(error.getLineNumber())
-				// .append(" : ")
-				sb.append("[").append(vx.getPath()).append("] ");
-			} else if (x instanceof TargetError) {
-				TargetError tx = (TargetError) x;
-				sb.append("[").append(tx.getLocation()).append("] ");
-			}
-			sb.append(x.getMessage());
-			if (x.getCause() != null) {
-				sb.append("\n\tCaused by:\n").append(x.getCause());
-			}
-		}
+        theErrors.forEach(x -> {
+            sb.append("\n");
+            if (x instanceof ValidationException) {
+                ValidationException vx = (ValidationException) x;
+                sb.append("[").append(vx.getPath()).append("] ");
+            } else if (x instanceof TargetError) {
+                TargetError tx = (TargetError) x;
+                sb.append("[").append(tx.getLocation()).append("] ");
+            }
+            sb.append(x.getMessage());
+            if (x.getCause() != null) {
+                sb.append("\n\tCaused by:\n").append(x.getCause());
+            }
+        });
 		sb.append("\n");
 		return sb.toString();
 	}
@@ -3154,42 +915,42 @@ substitute the canonical form for the short form so that checking does not have
 
 		Target tgt = ((TOSCAValidator) theContext.getValidator()).getTarget();
 
-		applyCanonicals(tgt.getTarget(), ((TOSCAValidator) theContext.getValidator()).canonicals, "/imports", true);
+		applyCanonicals(tgt.getTarget(), ((TOSCAValidator) theContext.getValidator()).getCanonicals(), "/imports", true);
 
-		for (ListIterator li = ((List) theValue).listIterator(); li.hasNext();) {
+        for (Object o : ((List) theValue)) {
 
-			Map.Entry importEntry = mapEntry(li.next());
+            Map.Entry importEntry = mapEntry(o);
 
-			Map def = (Map) importEntry.getValue();
-			debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Processing import {}", def);
+            Map def = (Map) importEntry.getValue();
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Processing import {}", def);
 
-			String tfile = (String) def.get("file");
-			Target tgti = this.locator.resolve(tfile);
-			if (tgti == null) {
-				theContext.addError("Failure to resolve import '" + def + "', imported from " + tgt, theRule, null,
-						null);
-				continue;
-			}
-			debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Import {} located at {}", def,
-					tgti.getLocation());
+            String tfile = (String) def.get("file");
+            Target tgti = this.locator.resolve(tfile);
+            if (tgti == null) {
+                theContext.addError("Failure to resolve import '" + def + "', " + IMPORTED_FROM + " " + tgt, theRule, null,
+                        null);
+                continue;
+            }
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Import {} located at {}", def,
+                    tgti.getLocation());
 
-			if (this.catalog.addTarget(tgti, tgt)) {
-				// we've never seen this import (location) before
-				try {
+            if (this.catalog.addTarget(tgti, tgt)) {
+                // we've never seen this import (location) before
+                try {
 
 					List<Target> tgtis = parseTarget(tgti);
 					if (tgtis.isEmpty()) {
                         continue;
                     }
 
-					if (tgtis.size() > 1) {
-						theContext.addError(
-								"Import '" + tgti + "', imported from " + tgt + ", contains multiple yaml documents",
-								theRule, null, null);
-						continue;
-					}
+                    if (tgtis.size() > 1) {
+                        theContext.addError(
+                                "Import '" + tgti + "', " + IMPORTED_FROM + " " + tgt + ", contains multiple yaml documents",
+                                theRule, null, null);
+                        continue;
+                    }
 
-					tgti = tgtis.get(0);
+                    tgti = tgtis.get(0);
 
 					if (tgt.getReport().hasErrors()) {
 						theContext.addError("Failure parsing import '" + tgti + IMPORTED_FROM + tgt, theRule, null,
@@ -3209,59 +970,33 @@ substitute the canonical form for the short form so that checking does not have
 				}
 			}
 
-			// replace with the actual location (also because this is what they
-			// get
-			// index by .. bad, this exposed catalog inner workings)
+            // replace with the actual location (also because this is what they
+            // get
+            // index by .. bad, this exposed catalog inner workings)
 
-			def.put("file", tgti.getLocation());
-		}
+            def.put("file", tgti.getLocation());
+        }
 	}
 
 	protected void node_templates_post_validation_handler(Object theValue, Rule theRule,
 			Validator.ValidationContext theContext) {
 		debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "entering node_templates_post_validation_handler {}",
 				theContext.getPath());
-		assert "map".equals(theRule.getType());
+		assert MAP.equals(theRule.getType());
 		Map<String, Map> nodeTemplates = (Map<String, Map>) theValue;
-		for (Iterator<Map.Entry<String, Map>> i = nodeTemplates.entrySet().iterator(); i.hasNext();) {
-			Map.Entry<String, Map> node = i.next();
-			try {
-				catalog.addTemplate(((TOSCAValidator) theContext.getValidator()).getTarget(), Construct.Node,
-						node.getKey(), node.getValue());
-				debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Node template {} has been cataloged",
-						node.getKey());
-			} catch (CatalogException cx) {
-				theContext.addError(cx.toString(), theRule, node, null);
-			}
-		}
+        nodeTemplates.entrySet().forEach(node -> {
+            try {
+                catalog.addTemplate(((TOSCAValidator) theContext.getValidator()).getTarget(), Construct.Node,
+                        node.getKey(), node.getValue());
+                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Node template {} has been cataloged",
+                        node.getKey());
+            } catch (CatalogException cx) {
+                theContext.addError(cx.toString(), theRule, node, null);
+            }
+        });
 	}
 
-	protected void inputs_post_validation_handler(Object theValue, Rule theRule,
-			Validator.ValidationContext theContext) {
-		debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "entering inputs_post_validation_handler {}",
-				theContext.getPath());
-		assert theRule.getType().equals("map");
 
-		// we'll repeat this test during checking but because we index inputs
-		// early
-		// we need it here too
-		if (theValue == null) {
-			return;
-		}
-
-		Map<String, Map> inputs = (Map<String, Map>) theValue;
-		for (Iterator<Map.Entry<String, Map>> i = inputs.entrySet().iterator(); i.hasNext();) {
-			Map.Entry<String, Map> input = i.next();
-			try {
-				catalog.addTemplate(((TOSCAValidator) theContext.getValidator()).getTarget(), Construct.Data,
-						input.getKey(), input.getValue());
-				debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Input {} has been cataloged",
-						input.getKey());
-			} catch (CatalogException cx) {
-				theContext.addError(cx.toString(), theRule, input, null);
-			}
-		}
-	}
 
 	private void process(String theProcessorSpec) throws CheckerException {
 
@@ -3288,359 +1023,504 @@ substitute the canonical form for the short form so that checking does not have
 		process(proc);
 	}
 
-	protected void check_artifact_definition(String theName, Map theDef, CheckContext theContext) {
-		theContext.enter(theName, Construct.Artifact);
+    @Catalogs(path = "/artifact_types")
+    protected void catalog_artifact_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(ARTIFACT_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Artifact, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-		try {
-			if (!checkDefinition(theName, theDef, theContext)) {
-				return;
-			}
-			// check artifact type
-			if (!checkType(Construct.Artifact, theDef, theContext)) {
-                return;
-            }
-		} finally {
-			theContext.exit();
-		}
-	}
+    /* */
+    @Checks(path = "/artifact_types")
+    protected void check_artifact_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(artifactCommon::checkArtifactTypeDefinition, theDefinition, theContext, ARTIFACT_TYPES);
+    }
 
-	/* */
-	protected void check_policy_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Policy);
+    @Catalogs(path = "/capability_types")
+    protected void catalog_capability_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(ConstCommon.CAPABILITY_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Capability, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+    /* */
+    @Checks(path = "/capability_types")
+    protected void check_capability_types(
+            Map<String, Map> theTypes, Checker.CheckContext theContext) {
+        abstractCheck(capabilityCommon::checkCapabilityTypeDefinition, theTypes, theContext, CAPABILITY_TYPES);
+    }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Policy, theName, theDefinition, Facet.properties, theContext);
-			}
+    @Catalogs(path = "/data_types")
+    protected void catalog_data_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(DATA_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Data, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			// the targets can be known node types or group types
-			List<String> targets = (List<String>) theDefinition.get("targets");
-			if (targets != null) {
-				if (checkDefinition("targets", targets, theContext)) {
-					for (String target : targets) {
-						if (!(this.catalog.hasType(Construct.Node, target)
-								|| this.catalog.hasType(Construct.Group, target))) {
-							theContext.addError(
-									"The 'targets' entry must contain a reference to a node type or group type, '"
-											+ target + "' is none of those",
-									null);
-						}
-					}
-				}
-			}
+    @Checks(path = "/data_types")
+    protected void check_data_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        abstractCheck(checkCommon::checkDataTypeDefinition, theDefinitions, theContext, DATA_TYPES);
 
-		} finally {
-			theContext.exit();
-		}
-	}
+    }
 
-	/* */
-	protected void check_group_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Group);
 
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+    @Catalogs(path = "/group_types")
+    protected void catalog_group_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(GROUP_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Group, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Group, theName, theDefinition, Facet.properties, theContext);
-			}
+    @Checks(path = "/group_types")
+    protected void check_group_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(groupCommon::checkGroupTypeDefinition, theDefinition, theContext, GROUP_TYPES);
+    }
 
-			if (theDefinition.containsKey("targets")) {
-				checkTypeReference(Construct.Node, theContext,
-						((List<String>) theDefinition.get("targets")).toArray(EMPTY_STRING_ARRAY));
-			}
+    @Catalogs(path = "/interface_types")
+    protected void catalog_interface_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(INTERFACE_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Interface, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			// interfaces
-			Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get("interfaces");
-			if (interfaces != null) {
-				try {
-					theContext.enter("interfaces");
-					for (Iterator<Map.Entry<String, Map>> i = interfaces.entrySet().iterator(); i.hasNext();) {
-						Map.Entry<String, Map> e = i.next();
-						check_type_interface_definition(e.getKey(), e.getValue(), theContext);
-					}
-				} finally {
-					theContext.exit();
-				}
-			}
+    @Checks(path = "/interface_types")
+    protected void check_interface_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(interfaceCommon::checkInterfaceTypeDefinition, theDefinition, theContext, INTERFACE_TYPES);
+    }
 
-		} finally {
-			theContext.exit();
-		}
-	}
+    @Catalogs(path = "/node_types")
+    protected void catalog_node_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(NODE_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Node, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-	/* */
-	protected void check_node_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Node);
+    /* */
+    @Checks(path = "/node_types")
+    protected void check_node_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(nodeCommon::checkNodeTypeDefinition, theDefinition, theContext, NODE_TYPES);
+    }
 
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+    @Catalogs(path = "/policy_types")
+    protected void catalog_policy_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(POLICY_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Policy, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Node, theName, theDefinition, Facet.properties, theContext);
-			}
+    /* */
+    @Checks(path = "/policy_types")
+    protected void check_policy_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(policyCommon::checkPolicyTypeDefinition, theDefinition, theContext, POLICY_TYPES);
+    }
 
-			if (theDefinition.containsKey("attributes")) {
-				check_properties((Map<String, Map>) theDefinition.get("attributes"), theContext);
-				checkTypeConstructFacet(Construct.Node, theName, theDefinition, Facet.attributes, theContext);
-			}
+    @Catalogs(path = "/relationship_types")
+    protected void catalog_relationship_types(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext) {
+        theContext.enter(RELATIONSHIP_TYPES);
+        try {
+            typeCommon.catalogTypes(Construct.Relationship, theDefinitions, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			// requirements
-			if (theDefinition.containsKey("requirements")) {
-				check_requirements((List<Map>) theDefinition.get("requirements"), theContext);
-			}
+    /* */
+    @Checks(path = "/relationship_types")
+    protected void check_relationship_types(
+            Map<String, Map> theDefinition, Checker.CheckContext theContext) {
+        abstractCheck(relationshipCommon::checkRelationshipTypeDefinition, theDefinition, theContext, RELATIONSHIP_TYPES);
+    }
 
-			// capabilities
-			if (theDefinition.containsKey(CAPABILITIES)) {
-				check_capabilities((Map<String, Map>) theDefinition.get(CAPABILITIES), theContext);
-			}
+    @Checks(path = "/topology_template/groups")
+    protected void check_groups(Map<String, Map> theGroups,
+                             Checker.CheckContext theContext) {
+        abstractCheck(groupCommon::checkGroupDefinition, theGroups, theContext, GROUPS);
+    }
 
-			// interfaces:
-			Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get("interfaces");
-			if (interfaces != null) {
-				try {
-					theContext.enter("interfaces");
-					for (Iterator<Map.Entry<String, Map>> i = interfaces.entrySet().iterator(); i.hasNext();) {
-						Map.Entry<String, Map> e = i.next();
-						check_type_interface_definition(e.getKey(), e.getValue(), theContext);
-					}
-				} finally {
-					theContext.exit();
-				}
-			}
+    @Checks(path = "/topology_template/policies")
+    protected void check_policies(List<Map<String, Map>> thePolicies,
+                               Checker.CheckContext theContext) {
+        theContext.enter(POLICIES);
 
-			// artifacts
+        try {
+            if (!checkCommon.checkDefinition(POLICIES, thePolicies, theContext)) {
+                return;
+            }
 
-		} finally {
-			theContext.exit();
-		}
-	}
+            thePolicies.forEach(policy -> {
+                assert policy.size() == 1;
+                Map.Entry<String, Map> e = policy.entrySet().iterator().next();
+                policyCommon.checkPolicyDefinition(e.getKey(), e.getValue(), theContext, catalog, target);
+            });
+        } finally {
+            theContext.exit();
+        }
+    }
 
-	/* */
-	protected void check_interface_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Interface);
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+    /* */
+    @Checks(path = "/topology_template/substitution_mappings")
+    protected void check_substitution_mappings(Map<String, Object> theSub,
+                                            Checker.CheckContext theContext) {
+        theContext.enter("substitution_mappings");
+        try {
+            //type is mandatory
+            String type = (String) theSub.get("node_type");
+            if (!typeCommon.checkTypeReference(Construct.Node, theContext, catalog, type)) {
+                theContext.addError("Unknown node type: " + type + "", null);
+                return; //not much to go on with
+            }
 
-			// not much else here: a list of operation_definitions, each with
-			// its
-			// implementation and inputs
+            Map<String, List> capabilities = (Map<String, List>) theSub.get(ConstCommon.CAPABILITIES);
+            if (null != capabilities) {
+                //the key must be a capability of the type
+                //the value is a 2 element list: first is a local node,
+                //second is the name of one of its capabilities
+                capabilities.entrySet().forEach(ce -> {
+                    if (null == facetCommon.findTypeFacetByName(Construct.Node, type,
+                            Facet.capabilities, ce.getKey(), catalog)) {
+                        theContext.addError("Unknown node type capability: " + ce.getKey() + ", type " + type, null);
+                    }
+                    if (!checkValidationOnCatalog(ce, "capability", theContext, Construct.Node)) {
+                        return;
+                    }
+                    String targetNode = (String) ce.getValue().get(0);
+                    Map<String, Object> targetNodeDef = (Map<String, Object>)
+                            catalog.getTemplate(theContext.target(), Construct.Node, targetNode);
+                    String targetCapability = (String) ce.getValue().get(1);
+                    String targetNodeType = (String) targetNodeDef.get("type");
+                    if (null == facetCommon.findTypeFacetByName(Construct.Node, targetNodeType,
+                            Facet.capabilities, targetCapability, catalog)) {
+                        theContext.addError("Invalid capability mapping capability: " + targetCapability + ". No such capability found for node template " + targetNode + ", of type " + targetNodeType, null);
+                    }
+                });
+            }
 
-			// check that common inputs are re-defined in a compatible manner
+            Map<String, List> requirements = (Map<String, List>) theSub.get(ConstCommon.REQUIREMENTS);
+            if (null != requirements) {
+                //the key must be a requirement of the type
+                requirements.entrySet().forEach(re -> {
+                    if (null == nodeCommon.findNodeTypeRequirementByName(type, re.getKey(), catalog)) {
+                        theContext.addError("Unknown node type requirement: " + re.getKey() + ", type " + type, null);
+                    }
+                    if (!checkValidationOnCatalog(re, "requirement", theContext, Construct.Node)) {
+                        return;
+                    }
+                    String targetNode = (String) re.getValue().get(0);
+                    Map<String, Object> targetNodeDef = (Map<String, Object>)
+                            catalog.getTemplate(theContext.target(), Construct.Node, targetNode);
+                    String targetRequirement = (String) re.getValue().get(1);
+                    String targetNodeType = (String) targetNodeDef.get("type");
+                    if (null == nodeCommon.findNodeTypeRequirementByName(targetNodeType, targetRequirement, catalog)) {
+                        theContext.addError("Invalid requirement mapping requirement: " + targetRequirement + ". No such requirement found for node template " + targetNode + ", of type " + targetNodeType, null);
+                    }
+                });
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
 
-			// check that the interface operations are overwritten in a
-			// compatible manner
-			// for (Iterator<Map.Entry<String,Map>> i = theDefinition.entrySet()
+    private boolean checkValidationOnCatalog(Map.Entry<String, List> target, String name, Checker.CheckContext theContext, Construct construct) {
+        List targetList = target.getValue();
+        if (targetList.size() != 2) {
+            theContext.addError("Invalid " + name + " mapping: " + target + ", expecting 2 elements", null);
+            return false;
+        }
 
-		} finally {
-			theContext.exit();
-		}
-	}
+        String targetNode = (String) targetList.get(0);
 
-	/* */
-	protected void check_artifact_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Artifact);
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+        Map<String, Object> targetNodeDef = (Map<String, Object>)
+                catalog.getTemplate(theContext.target(), construct, targetNode);
+        if (null == targetNodeDef) {
+            theContext.addError("Invalid " + name + " mapping node template: " + targetNode, null);
+            return false;
+        }
+        return true;
+    }
 
-		} finally {
-			theContext.exit();
-		}
-	}
+    @Override
+    @Checks(path = "/topology_template/artifacts")
+    public void check_template_artifacts_definition(
+            Map<String, Object> theDefinition,
+            Checker.CheckContext theContext) {
+        theContext.enter(ARTIFACTS);
+        theContext.exit();
+    }
 
-	/* */
-	protected void check_relationship_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Relationship);
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+    @Checks(path = "/topology_template/relationship_templates")
+    protected void check_relationship_templates(Map theTemplates,
+                                                Checker.CheckContext theContext) {
+        abstractCheck(relationshipCommon::checkRelationshipTemplateDefinition, theTemplates, theContext, RELATIONSHIP_TEMPLATES);
+    }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Relationship, theName, theDefinition, Facet.properties, theContext);
-			}
+    @Checks(path = "topology_template/outputs")
+    protected void check_outputs(Map<String, Map> theOutputs,
+                              Checker.CheckContext theContext) {
+        abstractCheck(inputsOutputsCommon::checkOutputDefinition, theOutputs, theContext, OUTPUTS);
+    }
 
-			if (theDefinition.containsKey("attributes")) {
-				check_properties((Map<String, Map>) theDefinition.get("attributes"), theContext);
-				checkTypeConstructFacet(Construct.Relationship, theName, theDefinition, Facet.attributes, theContext);
-			}
+    /* */
+    @Checks(path = "/topology_template/node_templates")
+    protected void check_node_templates(Map<String, Map> theTemplates,
+                                     Checker.CheckContext theContext) {
+        abstractCheck(nodeCommon::checkNodeTemplateDefinition, theTemplates, theContext, NODE_TEMPLATES);
+    }
 
-			Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get("interfaces");
-			if (interfaces != null) {
-				theContext.enter("interfaces");
-				for (Iterator<Map.Entry<String, Map>> i = interfaces.entrySet().iterator(); i.hasNext();) {
-					Map.Entry<String, Map> e = i.next();
-					check_type_interface_definition(e.getKey(), e.getValue(), theContext);
-				}
-				theContext.exit();
-			}
+    /* */
+    @Override
+    @Checks(path = "/topology_template/inputs")
+    public void check_inputs(Map<String, Map> theInputs,
+                             Checker.CheckContext theContext) {
+        abstractCheck(inputsOutputsCommon::checkInputDefinition, theInputs, theContext, INPUTS);
+    }
 
-			if (theDefinition.containsKey(VALID_TARGET_TYPES)) {
-				checkTypeReference(Construct.Capability, theContext,
-						((List<String>) theDefinition.get(VALID_TARGET_TYPES)).toArray(EMPTY_STRING_ARRAY));
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+    @Override
+    public void validationHook(String theTiming,
+                               Object theTarget,
+                               Rule theRule,
+                               Validator.ValidationContext theContext) {
 
-	/* */
-	protected void check_capability_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Capability);
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "looking up validation handler for {}, {} {}", theRule.getName(), theTiming, theContext.getPath());
+        if (!invokeHook(theRule.getName() + "_" + theTiming + "_validation_handler",
+                validationHookArgTypes,
+                theTarget, theRule, theContext)) {
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "no validation handler for {}", theRule.getName() + "_" + theTiming);
+        }
+    }
+    private boolean invokeHook(String theHookName,
+                               Class[] theArgTypes,
+                               Object... theArgs) {
 
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+        Invokable hookHandler = null;
+        try {
+            Method m = Checker.class.getDeclaredMethod(
+                    theHookName, theArgTypes);
+            m.setAccessible(true);
+            hookHandler = Invokable.from(m);
+        } catch (NoSuchMethodException nsmx) {
+            //that's ok, not every rule has to have a handler
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), getClass().getName(), "That's ok, not every rule has to have a handler. Method name =", theHookName);
+        }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Capability, theName, theDefinition, Facet.properties, theContext);
-			}
+        if (hookHandler != null) {
+            try {
+                hookHandler.invoke(this, theArgs);
+            } catch (InvocationTargetException | IllegalAccessException itx) {
+                errLogger.log(LogLevel.WARN, this.getClass().getName(), "Invocation failed for hook handler {} {}", theHookName, itx);
+            } catch (Exception x) {
+                errLogger.log(LogLevel.WARN, this.getClass().getName(), "Hook handler failed {} {}", theHookName, x);
+            }
+        }
 
-			if (theDefinition.containsKey("attributes")) {
-				check_attributes((Map<String, Map>) theDefinition.get("attributes"), theContext);
-				checkTypeConstructFacet(Construct.Capability, theName, theDefinition, Facet.attributes, theContext);
-			}
+        return hookHandler != null;
+    }
 
-			// valid_source_types: see capability_type_definition
-			// unclear: how is the valid_source_types list definition eveolving
-			// across
-			// the type hierarchy: additive, overwriting, ??
-			if (theDefinition.containsKey("valid_source_types")) {
-				checkTypeReference(Construct.Node, theContext,
-						((List<String>) theDefinition.get("valid_source_types")).toArray(EMPTY_STRING_ARRAY));
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+    public void inputs_post_validation_handler(Object theValue, Rule theRule,
+                                               Validator.ValidationContext theContext) {
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "entering inputs_post_validation_handler {}",
+                theContext.getPath());
+        assert MAP.equals(theRule.getType());
 
-	/* */
-	protected void check_data_type_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName, Construct.Data);
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
+        // we'll repeat this test during checking but because we index inputs
+        // early
+        // we need it here too
+        if (theValue == null) {
+            return;
+        }
 
-			if (theDefinition.containsKey(PROPERTIES)) {
-				check_properties((Map<String, Map>) theDefinition.get(PROPERTIES), theContext);
-				checkTypeConstructFacet(Construct.Data, theName, theDefinition, Facet.properties, theContext);
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+        Map<String, Map> inputs = (Map<String, Map>) theValue;
+        inputs.entrySet().forEach(input -> {
+            try {
+                catalog.addTemplate(((TOSCAValidator) theContext.getValidator()).getTarget(), Construct.Data,
+                        input.getKey(), input.getValue());
+                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Input {} has been cataloged",
+                        input.getKey());
+            } catch (CatalogException cx) {
+                theContext.addError(cx.toString(), theRule, input, null);
+            }
+        });
+    }
 
-	/*
-	 * top level rule, we collected the whole information set. this is where
-	 * checking starts
-	 */
-	protected void check_service_template_definition(Map<String, Object> theDef, CheckContext theContext) {
-		theContext.enter("");
+    /* */
+    public void check_node_type_definition(String theName, Map theDefinition, Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Node);
 
-		if (theDef == null) {
-			theContext.addError("Empty template", null);
-			return;
-		}
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
 
-		// !!! imports need to be processed first now that catalogging takes
-		// place at check time!!
+            checkProperties(theName, theDefinition, theContext, PROPERTIES, Construct.Node, Facet.properties);
+            checkProperties(theName, theDefinition, theContext, ATTRIBUTES, Construct.Node, Facet.attributes);
+            // requirements
+            checkRequirements(theDefinition, theContext, requirementCommon);
+            // capabilities
+            checkCapabilities(theDefinition, theContext, capabilityCommon);
+            // interfaces:
+            checkInterfaces(theDefinition, theContext);
 
-		// first catalog whatever it is there to be cataloged so that the checks
-		// can perform cross-checking
-		for (Iterator<Map.Entry<String, Object>> ri = theDef.entrySet().iterator(); ri.hasNext();) {
-			Map.Entry<String, Object> e = ri.next();
-			catalogs(e.getKey(), e.getValue(), theContext);
-		}
+            // artifacts
 
-		for (Iterator<Map.Entry<String, Object>> ri = theDef.entrySet().iterator(); ri.hasNext();) {
-			Map.Entry<String, Object> e = ri.next();
-			checks(e.getKey(), e.getValue(), theContext);
-		}
-		theContext.exit();
-	}
+        } finally {
+            theContext.exit();
+        }
+    }
 
-	protected void check_attribute_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName);
-		try {
-			if (!checkDefinition(theName, theDefinition, theContext)) {
-				return;
-			}
-			if (!checkDataType(theDefinition, theContext)) {
-				return;
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+    private void checkCapabilities(Map theDefinition, CheckContext theContext, CapabilityCommon capabilityCommon) {
+        if (theDefinition.containsKey(CAPABILITIES)) {
+            capabilityCommon.check_capabilities((Map<String, Map>) theDefinition.get(CAPABILITIES), theContext, catalog);
+        }
+    }
 
-	public void check_attributes(Map<String, Map> theDefinitions, CheckContext theContext) {
-		theContext.enter("attributes");
-		try {
-			if (!checkDefinition("attributes", theDefinitions, theContext)) {
+    private void checkRequirements(Map theDefinition, CheckContext theContext, RequirementCommon requirementCommon) {
+        if (theDefinition.containsKey(REQUIREMENTS)) {
+            requirementCommon.check_requirements((List<Map>) theDefinition.get(REQUIREMENTS), theContext, catalog);
+        }
+    }
+
+    private void checkProperties(String theName, Map theDefinition, CheckContext theContext, String definition, Construct node, Facet facet) {
+        if (theDefinition.containsKey(definition)) {
+            propertiesCommon.check_properties((Map<String, Map>) theDefinition.get(definition), theContext, catalog);
+            facetCommon.checkTypeConstructFacet(node, theName, theDefinition, facet, theContext, catalog);
+        }
+    }
+
+    /* */
+    public void check_data_type_definition(String theName, Map theDefinition, Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Data);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
                 return;
             }
 
-			for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext();) {
-				Map.Entry<String, Map> e = i.next();
-				check_attribute_definition(e.getKey(), e.getValue(), theContext);
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+            checkProperties(theName, theDefinition, theContext, PROPERTIES, Construct.Data, Facet.properties);
+        } finally {
+            theContext.exit();
+        }
+    }
 
-	protected void check_property_definition(String theName, Map theDefinition, CheckContext theContext) {
-		theContext.enter(theName);
-		if (!checkDefinition(theName, theDefinition, theContext)) {
-			return;
-		}
-		// check the type
-		if (!checkDataType(theDefinition, theContext)) {
-			return;
-		}
-		// check default value is compatible with type
-		Object defaultValue = theDefinition.get("default");
-		if (defaultValue != null) {
-			checkDataValuation(defaultValue, theDefinition, theContext);
-		}
+    /* */
+    public void check_capability_type_definition(String theName, Map theDefinition, Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Capability);
 
-		theContext.exit();
-	}
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
 
-	public void check_properties(Map<String, Map> theDefinitions, CheckContext theContext) {
-		theContext.enter(PROPERTIES);
-		try {
-			if (!checkDefinition(PROPERTIES, theDefinitions, theContext)) {
+            checkProperties(theName, theDefinition, theContext, PROPERTIES, Construct.Capability, Facet.properties);
+
+            if (theDefinition.containsKey(ATTRIBUTES)) {
+                attributesCommon.check_attributes((Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Capability, theName, theDefinition, Facet.attributes, theContext, catalog);
+            }
+
+            // valid_source_types: see capability_type_definition
+            // unclear: how is the valid_source_types list definition eveolving
+            // across
+            // the type hierarchy: additive, overwriting, ??
+            if (theDefinition.containsKey("valid_source_types")) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog,
+                        ((List<String>) theDefinition.get("valid_source_types")).toArray(EMPTY_STRING_ARRAY));
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+
+    /* */
+    public void check_group_type_definition(String theName, Map theDefinition, Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Group);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
                 return;
             }
 
-			for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext();) {
-				Map.Entry<String, Map> e = i.next();
-				check_property_definition(e.getKey(), e.getValue(), theContext);
-			}
-		} finally {
-			theContext.exit();
-		}
-	}
+            checkProperties(theName, theDefinition, theContext, PROPERTIES, Construct.Group, Facet.properties);
+
+            if (theDefinition.containsKey(TARGETS)) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog,
+                        ((List<String>) theDefinition.get(TARGETS)).toArray(EMPTY_STRING_ARRAY));
+            }
+
+            // interfaces
+            checkInterfaces(theDefinition, theContext);
+
+        } finally {
+            theContext.exit();
+        }
+    }
 
+    private void checkInterfaces(Map theDefinition, CheckContext theContext) {
+        Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get(INTERFACES);
+        if (interfaces != null) {
+            try {
+                theContext.enter(INTERFACES);
+                interfaces.forEach((key, value) -> interfaceCommon.check_type_interface_definition(key, value, theContext, catalog));
+            } finally {
+                theContext.exit();
+            }
+        }
+    }
+
+    /* */
+    public void check_interface_type_definition(String theName, Map theDefinition, Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Interface);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            // not much else here: a list of operation_definitions, each with
+            // its
+            // implementation and inputs
+
+            // check that common inputs are re-defined in a compatible manner
+
+            // check that the interface operations are overwritten in a
+            // compatible manner
+            // for (Iterator<Map.Entry<String,Map>> i = theDefinition.entrySet()
+
+        } finally {
+            theContext.exit();
+        }
+    }
 }
 
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/IChecker.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/IChecker.java
new file mode 100644
index 0000000..be77500
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/IChecker.java
@@ -0,0 +1,21 @@
+package org.onap.sdc.dcae.checker;
+
+import kwalify.Rule;
+import kwalify.Validator;
+
+import java.util.Map;
+
+public interface IChecker {
+    void check_template_artifacts_definition(
+            Map<String, Object> theDefinition,
+            Checker.CheckContext theContext);
+
+    /* */
+    void check_inputs(Map<String, Map> theInputs,
+                      Checker.CheckContext theContext);
+
+    void validationHook(String theTiming,
+                        Object theTarget,
+                        Rule theRule,
+                        Validator.ValidationContext theContext);
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Target.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Target.java
index b630564..9dd5db4 100644
--- a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Target.java
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/Target.java
@@ -1,27 +1,16 @@
 package org.onap.sdc.dcae.checker;
 
-import org.onap.sdc.common.onaplog.OnapLoggerDebug;
-import org.onap.sdc.common.onaplog.OnapLoggerError;
-
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.io.Reader;
 import java.io.BufferedReader;
 import java.io.IOException;
-
+import java.io.InputStreamReader;
+import java.io.Reader;
 import java.net.URI;
-import java.net.URL;
-import java.net.MalformedURLException;
 
 /**
  * Represents a yaml document to be parsed/validated/checked
  */
 public class Target {
 
-	private static OnapLoggerError errLogger = OnapLoggerError.getInstance();
-	private static OnapLoggerDebug debugLogger = OnapLoggerDebug.getInstance();
-
-
 	private String 				name;			//maintained mainly for logging
 	private URI					 	location;
 	private Object 				target;		//this is the parsed form of the target
@@ -72,7 +61,6 @@ public class Target {
 	}
 
 	public String toString() {
-		//return String.format("Target %s (%.20s ...)", this.location, this.target == null ? "" : this.target.toString());
 		return String.format("Target %s at %s", this.name, this.location);
 
 	}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ArtifactCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ArtifactCommon.java
new file mode 100644
index 0000000..32a78c1
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ArtifactCommon.java
@@ -0,0 +1,31 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.Checker;
+import org.onap.sdc.dcae.checker.Construct;
+
+import java.util.Map;
+
+public class ArtifactCommon extends BaseCommon {
+
+    private static ArtifactCommon instance;
+
+    public synchronized static ArtifactCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new ArtifactCommon();
+        }
+        return instance;
+    }
+
+    private ArtifactCommon() {}
+    public void checkArtifactTypeDefinition(String theName,
+                                             Map theDefinition,
+                                             Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Artifact);
+        try {
+            CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext);
+        } finally {
+            theContext.exit();
+        }
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/AttributesCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/AttributesCommon.java
new file mode 100644
index 0000000..afe8ada
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/AttributesCommon.java
@@ -0,0 +1,72 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.Catalog;
+import org.onap.sdc.dcae.checker.Checker;
+
+import java.util.Iterator;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.ATTRIBUTES;
+
+public class AttributesCommon extends BaseCommon {
+    private static AttributesCommon instance;
+
+    public synchronized static AttributesCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new AttributesCommon();
+        }
+        return instance;
+    }
+
+    private AttributesCommon() {}
+
+    public void checkAttributes(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext, Catalog catalog) {
+        theContext.enter(ATTRIBUTES);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(ATTRIBUTES, theDefinitions, theContext)) {
+                return;
+            }
+
+            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext(); ) {
+                Map.Entry<String, Map> e = i.next();
+                checkAttributeDefinition(e.getKey(), e.getValue(), theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkAttributeDefinition(
+            String theName, Map theDefinition, Checker.CheckContext theContext, Catalog catalog) {
+        DataCommon dataCommon = DataCommon.getInstance();
+        theContext.enter(theName);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+            if (!dataCommon.checkDataType(theDefinition, theContext, catalog)) {
+                return;
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void check_attributes(Map<String, Map> theDefinitions, Checker.CheckContext theContext, Catalog catalog) {
+        theContext.enter("attributes");
+        try {
+            if (!CheckCommon.getInstance().checkDefinition("attributes", theDefinitions, theContext))
+                return;
+
+            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext();) {
+                Map.Entry<String, Map> e = i.next();
+                checkAttributeDefinition(e.getKey(), e.getValue(), theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/BaseCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/BaseCommon.java
new file mode 100644
index 0000000..43bda09
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/BaseCommon.java
@@ -0,0 +1,9 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.common.onaplog.OnapLoggerDebug;
+import org.onap.sdc.common.onaplog.OnapLoggerError;
+
+public class BaseCommon {
+    protected static OnapLoggerError errLogger = OnapLoggerError.getInstance();
+    protected static OnapLoggerDebug debugLogger = OnapLoggerDebug.getInstance();
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CapabilityCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CapabilityCommon.java
new file mode 100644
index 0000000..08a1dd2
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CapabilityCommon.java
@@ -0,0 +1,190 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.Catalog;
+import org.onap.sdc.dcae.checker.Checker;
+import org.onap.sdc.dcae.checker.Construct;
+import org.onap.sdc.dcae.checker.Facet;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+
+public class CapabilityCommon extends BaseCommon {
+
+    private static CapabilityCommon instance;
+
+    public synchronized static CapabilityCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new CapabilityCommon();
+        }
+        return instance;
+    }
+
+    private CapabilityCommon() {}
+
+
+
+    public void check_capabilities(Map<String, Map> theDefinition,
+                                    Checker.CheckContext theContext, Catalog catalog) {
+        theContext.enter(CAPABILITIES);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(CAPABILITIES, theDefinition, theContext)) {
+                return;
+            }
+
+            for (Iterator<Map.Entry<String, Map>> i = theDefinition.entrySet().iterator(); i.hasNext(); ) {
+                Map.Entry<String, Map> e = i.next();
+                checkCapabilityDefinition(e.getKey(), e.getValue(), theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    /* A capability definition appears within the context ot a node type */
+    public void checkCapabilityDefinition(String theName,
+                                          Map theDef,
+                                          Checker.CheckContext theContext,
+                                          Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName, Construct.Capability);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+
+            //check capability type
+            if (!typeCommon.checkType(Construct.Capability, theDef, theContext, catalog)) {
+                return;
+            }
+
+            //check properties
+            if (!facetCommon.checkFacetAugmentation(
+                    Construct.Capability, theDef, Facet.properties, theContext, catalog)) {
+                return;
+            }
+
+            //check attributes
+            if (!facetCommon.checkFacetAugmentation(
+                    Construct.Capability, theDef, Facet.attributes, theContext, catalog)) {
+                return;
+            }
+
+            //valid_source_types: should point to valid template nodes
+            if (theDef.containsKey(VALID_SOURCE_TYPES)) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog,
+                        ((List<String>) theDef.get(VALID_SOURCE_TYPES)).toArray(EMPTY_STRING_ARRAY));
+                //per A.6.1.4 there is an additinal check to be performed here:
+                //"Any Node Type (names) provides as values for the valid_source_types keyname SHALL be type-compatible (i.e., derived from the same parent Node Type) with any Node Types defined using the same keyname in the parent Capability Type."
+            }
+            //occurences: were verified in range_definition
+
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkCapabilityTypeDefinition(String theName,
+                                              Map theDefinition,
+                                              Checker.CheckContext theContext,
+                                              Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        AttributesCommon attributesCommon = AttributesCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName, Construct.Capability);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Capability, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+
+            if (theDefinition.containsKey(ATTRIBUTES)) {
+                attributesCommon.checkAttributes(
+                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Capability, theName, theDefinition,
+                        Facet.attributes, theContext, catalog);
+            }
+
+            //valid_source_types: see capability_type_definition
+            //unclear: how is the valid_source_types list definition eveolving across
+            //the type hierarchy: additive, overwriting, ??
+            if (theDefinition.containsKey(VALID_SOURCE_TYPES)) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog,
+                        ((List<String>) theDefinition.get(VALID_SOURCE_TYPES)).toArray(EMPTY_STRING_ARRAY));
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkCapabilitiesAssignmentDefinition(
+            Map<String, Map> theCapabilities, Checker.CheckContext theContext, Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(CAPABILITIES);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(CAPABILITIES, theCapabilities, theContext)) {
+                return;
+            }
+
+            //the node type for the node template enclosing these requirements
+            String nodeType = (String) catalog.getTemplate(
+                    theContext.target(),
+                    Construct.Node,
+                    theContext.enclosingConstruct(Construct.Node))
+                    .get("type");
+
+            for (Iterator<Map.Entry<String, Map>> ci =
+                 theCapabilities.entrySet().iterator();
+                 ci.hasNext(); ) {
+
+                Map.Entry<String, Map> ce = ci.next();
+
+                String capabilityName = ce.getKey();
+                Map capabilityDef = facetCommon.findTypeFacetByName(Construct.Node, nodeType,
+                        Facet.capabilities, capabilityName, catalog);
+                if (capabilityDef == null) {
+                    theContext.addError("No capability " + capabilityName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
+                    continue;
+                }
+
+                checkCapabilityAssignmentDefinition(
+                        capabilityName, ce.getValue(), capabilityDef, theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkCapabilityAssignmentDefinition(
+            String theCapabilityName,
+            Map theAssignment,
+            Map theDefinition,
+            Checker.CheckContext theContext,
+            Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(theCapabilityName, Construct.Capability);
+        try {
+            String capabilityType = (String) theDefinition.get("type");
+            //list of property and attributes assignments
+            facetCommon.checkFacet(Construct.Capability, theAssignment, capabilityType,
+                    Facet.properties, theContext, catalog);
+            facetCommon.checkFacet(Construct.Capability, theAssignment, capabilityType,
+                    Facet.attributes, theContext, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CheckCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CheckCommon.java
new file mode 100644
index 0000000..300420f
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/CheckCommon.java
@@ -0,0 +1,79 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.PROPERTIES;
+
+public class CheckCommon extends BaseCommon {
+    private static CheckCommon instance = null;
+
+    public synchronized static CheckCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new CheckCommon();
+        }
+        return instance;
+    }
+
+    private CheckCommon() {}
+
+    public boolean checkDefinition(String theName,
+                               Map theDefinition,
+                               Checker.CheckContext theContext) {
+    if (theDefinition == null) {
+        theContext.addError("Missing definition for " + theName, null);
+        return false;
+    }
+
+    if (theDefinition.isEmpty()) {
+        theContext.addError("Empty definition for " + theName, null);
+        return false;
+    }
+
+    return true;
+    }
+
+    public boolean checkDefinition(String theName,
+                                    List theDefinition,
+                                    Checker.CheckContext theContext) {
+        if (theDefinition == null) {
+            theContext.addError("Missing definition for " + theName, null);
+            return false;
+        }
+
+        if (theDefinition.isEmpty()) {
+            theContext.addError("Empty definition for " + theName, null);
+            return false;
+        }
+
+        return true;
+    }
+
+    public void checkDataTypeDefinition(String theName,
+                                        Map theDefinition,
+                                        Checker.CheckContext theContext,
+                                        Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        theContext.enter(theName, Construct.Data);
+        try {
+            if (!checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Data, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ConstCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ConstCommon.java
new file mode 100644
index 0000000..2a57e77
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/ConstCommon.java
@@ -0,0 +1,38 @@
+package org.onap.sdc.dcae.checker.common;
+
+public class ConstCommon {
+    public static final String PROPERTIES = "properties";
+    public static final String TYPE = " type ";
+    public static final String DEFAULT = "default";
+    public static final String ATTRIBUTES = "attributes";
+    public static final String DATA_TYPES = "data_types";
+    public static final String VALID_SOURCE_TYPES = "valid_source_types";
+    public static final String RELATIONSHIP_TYPES = "relationship_types";
+    public static final String INTERFACES = "interfaces";
+    public static final String VALID_TARGET_TYPES = "valid_target_types";
+    public static final String ARTIFACT_TYPES = "artifact_types";
+    public static final String INTERFACE_TYPES = "interface_types";
+    public static final String NODE_TYPES = "node_types";
+    public static final String REQUIREMENTS = "requirements";
+    public static final String CAPABILITIES = "capabilities";
+    public static final String GROUP_TYPES = "group_types";
+    public static final String TARGETS_CONSTANT = "targets";
+    public static final String POLICY_TYPES = "policy_types";
+    public static final String IS_NONE_OF_THOSE = "' is none of those";
+    public static final String INPUTS = "inputs";
+    public static final String CAPABILITY = "capability";
+    public static final String ARTIFACTS = "artifacts";
+    public static final String WAS_DEFINED_FOR_THE_NODE_TYPE = " was defined for the node type ";
+    public static final String UNKNOWN = "Unknown ";
+    public static final String CAPABILITY_TYPES = "capability_types";
+    public static final String GROUPS = "groups";
+    public static final String RELATIONSHIP_TEMPLATES = "relationship_templates";
+    public static final String OUTPUTS = "outputs";
+    public static final String NODE_TEMPLATES = "node_templates";
+    public static final String POLICIES = "policies";
+    public static final String IMPORTED_FROM = "imported from";
+    public static final String MAP = "map";
+    public static final String TARGETS = "targets";
+    public static final String[] EMPTY_STRING_ARRAY = new String[0];
+    private ConstCommon() {}
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/DataCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/DataCommon.java
new file mode 100644
index 0000000..52ceef3
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/DataCommon.java
@@ -0,0 +1,102 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Map;
+
+public class DataCommon extends BaseCommon {
+
+    private static DataCommon instance;
+
+    public synchronized static DataCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new DataCommon();
+        }
+        return instance;
+    }
+
+    private DataCommon() {}
+
+    /* the type can be:
+     *   a known type: predefined or user-defined
+     *   a collection (list or map) and then check that the entry_schema points to one of the first two cases (is that it?)
+     */
+    public boolean checkDataType(Map theSpec, Checker.CheckContext theContext, Catalog catalog) {
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        if (!typeCommon.checkType(Construct.Data, theSpec, theContext, catalog)) {
+            return false;
+        }
+
+        String type = (String) theSpec.get("type");
+        if (/*isCollectionType(type)*/
+                "list".equals(type) || "map".equals(type)) {
+            Map entrySchema = (Map) theSpec.get("entry_schema");
+            if (entrySchema == null) {
+                //maybe issue a warning ?? or is 'string' the default??
+                return true;
+            }
+
+            if (!catalog.hasType(Construct.Data, (String) entrySchema.get("type"))) {
+                theContext.addError("Unknown entry_schema type: " + entrySchema, null);
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /*
+     * For inputs/properties/attributes/(parameters). It is the caller's
+     * responsability to provide the value (from a 'default', inlined, ..)
+     *
+     * @param theDef the definition of the given construct/facet as it appears in
+     * 			its enclosing type definition.
+     * @param
+     */
+    public boolean checkDataValuation(Object theExpr,
+                                       Map<String, ?> theDef,
+                                       Checker.CheckContext theContext) {
+        //first check if the expression is a function, if not handle it as a value assignment
+        Data.Function f = Data.function(theExpr);
+        if (f != null) {
+            return f.evaluator()
+                    .eval(theExpr, theDef, theContext);
+        } else {
+            Data.Type type = Data.typeByName((String) theDef.get("type"));
+            if (type != null) {
+                Data.Evaluator evaluator;
+
+                evaluator = type.evaluator();
+                if (evaluator == null) {
+                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "No value evaluator available for type {}", type);
+                } else {
+                    if ((theExpr != null) && (!evaluator.eval(theExpr, theDef, theContext))) {
+                        return false;
+                    }
+                }
+
+
+                evaluator = type.constraintsEvaluator();
+                if (evaluator == null) {
+                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "No constraints evaluator available for type {}", type);
+                } else {
+                    if (theExpr != null) {
+                        if (!evaluator.eval(theExpr, theDef, theContext)) {
+                            return false;
+                        }
+                    } else {
+                        //should have a null value validatorT
+                    }
+                }
+
+                return true;
+            } else {
+                theContext.addError("Expression " + theExpr + " of " + theDef + " could not be evaluated", null);
+                return false;
+            }
+        }
+    }
+
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/FacetCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/FacetCommon.java
new file mode 100644
index 0000000..93c8416
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/FacetCommon.java
@@ -0,0 +1,320 @@
+package org.onap.sdc.dcae.checker.common;
+
+import com.google.common.collect.MapDifference;
+import com.google.common.collect.Maps;
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.DEFAULT;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.TYPE;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.UNKNOWN;
+
+public class FacetCommon extends BaseCommon {
+
+    private static FacetCommon instance;
+
+    public synchronized static FacetCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new FacetCommon();
+        }
+        return instance;
+    }
+
+    private FacetCommon() {}
+    /**
+     * Given the type of a certain construct (node type for example), look up
+     * in one of its facets (properties, capabilities, ..) for one of the given
+     * facet type (if looking in property, one of the given data type).
+     *
+     * @return a map of all facets of the given type, will be empty to signal
+     * none found
+     * <p>
+     * Should we look for a facet construct of a compatible type: any type derived
+     * from the given facet's construct type??
+     */
+    public Map<String, Map>
+    findTypeFacetByType(Construct theTypeConstruct,
+                        String theTypeName,
+                        Facet theFacet,
+                        String theFacetType,
+                        Catalog catalog) {
+
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType {}, {}: {} {}", theTypeName, theTypeConstruct, theFacetType, theFacet);
+        Map<String, Map> res = new HashMap<>();
+        Iterator<Map.Entry<String, Map>> i =
+                catalog.hierarchy(theTypeConstruct, theTypeName);
+        while (i.hasNext()) {
+            Map.Entry<String, Map> typeSpec = i.next();
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, Checking {} type {}", theTypeConstruct, typeSpec.getKey());
+            Map<String, Map> typeFacet =
+                    (Map<String, Map>) typeSpec.getValue().get(theFacet.name());
+            if (typeFacet == null) {
+                continue;
+            }
+            Iterator<Map.Entry<String, Map>> fi = typeFacet.entrySet().iterator();
+            while (fi.hasNext()) {
+                Map.Entry<String, Map> facet = fi.next();
+                String facetType = (String) facet.getValue().get("type");
+                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, Checking {} type {}", facet.getKey(), facetType);
+
+                //here is the question: do we look for an exact match or ..
+                //now we check that the type has a capability of a type compatible
+                //(equal or derived from) the given capability type.
+                if (catalog.isDerivedFrom(
+                        theFacet.construct(), facetType, theFacetType)) {
+                    res.putIfAbsent(facet.getKey(), facet.getValue());
+                }
+            }
+        }
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByType, found {}", res);
+
+        return res;
+    }
+
+    public Map<String, Object>
+    findTypeFacetByName(Construct theTypeConstruct,
+                        String theTypeName,
+                        Facet theFacet,
+                        String theFacetName,
+                        Catalog catalog) {
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByName {} {}", theTypeConstruct, theTypeName);
+        Iterator<Map.Entry<String, Map>> i =
+                catalog.hierarchy(theTypeConstruct, theTypeName);
+        while (i.hasNext()) {
+            Map.Entry<String, Map> typeSpec = i.next();
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findTypeFacetByName, Checking {} type {}", theTypeConstruct, typeSpec.getKey());
+            Map<String, Map> typeFacet =
+                    (Map<String, Map>) typeSpec.getValue().get(theFacet.name());
+            if (typeFacet == null) {
+                continue;
+            }
+            Map<String, Object> facet = typeFacet.get(theFacetName);
+            if (facet != null) {
+                return facet;
+            }
+        }
+        return null;
+    }
+
+    /* Check that a particular facet (properties, attributes) of a construct type
+     * (node type, capability type, etc) is correctly (consistenly) defined
+     * across a type hierarchy
+     */
+    public boolean checkTypeConstructFacet(Construct theConstruct,
+                                           String theTypeName,
+                                           Map theTypeSpec,
+                                           Facet theFacet,
+                                           Checker.CheckContext theContext,
+                                           Catalog catalog) {
+        Map<String, Map> defs =
+                (Map<String, Map>) theTypeSpec.get(theFacet.name());
+        if (null == defs) {
+            return true;
+        }
+
+        boolean res = true;
+
+        //given that the type was cataloged there will be at least one entry
+        Iterator<Map.Entry<String, Map>> i =
+                catalog.hierarchy(theConstruct, theTypeName);
+        if (!i.hasNext()) {
+            theContext.addError(
+                    "The type " + theTypeName + " needs to be cataloged before attempting 'checkTypeConstruct'", null);
+            return false;
+        }
+        i.next(); //skip self
+        while (i.hasNext()) {
+            Map.Entry<String, Map> e = i.next();
+            Map<String, Map> superDefs = (Map<String, Map>) e.getValue()
+                    .get(theFacet.name());
+            if (null == superDefs) {
+                continue;
+            }
+            //this computes entries that appear on both collections but with different values, i.e. the re-defined properties
+            Map<String, MapDifference.ValueDifference<Map>> diff = Maps.difference(defs, superDefs).entriesDiffering();
+
+            for (Iterator<Map.Entry<String, MapDifference.ValueDifference<Map>>> di = diff.entrySet().iterator(); di.hasNext(); ) {
+                Map.Entry<String, MapDifference.ValueDifference<Map>> de = di.next();
+                MapDifference.ValueDifference<Map> dediff = de.getValue();
+                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "{} type {}: {} has been re-defined between the {} types {} and {}", theConstruct, theFacet, de.getKey(), theConstruct, e.getKey(), theTypeName);
+                //for now we just check that the type is consistenly re-declared
+                if (!catalog.isDerivedFrom(theFacet.construct(),
+                        (String) dediff.leftValue().get("type"),
+                        (String) dediff.rightValue().get("type"))) {
+                    theContext.addError(
+                            theConstruct + TYPE + theFacet + ", redefiniton changed its type: " + de.getKey() + " has been re-defined between the " + theConstruct + " types " + e.getKey() + " and " + theTypeName + " in an incompatible manner", null);
+                    res = false;
+                }
+            }
+        }
+
+        return res;
+    }
+
+    /* Augmentation occurs in cases such as the declaration of capabilities within a node type.
+     * In such cases the construct facets (the capabilitity's properties) can redefine (augment) the
+     * specification found in the construct type.
+     */
+    public boolean checkFacetAugmentation(Construct theConstruct,
+                                          Map theSpec,
+                                          Facet theFacet,
+                                          Checker.CheckContext theContext,
+                                          Catalog catalog) {
+        return checkFacetAugmentation(theConstruct, theSpec, null, theFacet, theContext, catalog);
+    }
+
+    public boolean checkFacetAugmentation(Construct theConstruct,
+                                          Map theSpec,
+                                          String theSpecType,
+                                          Facet theFacet,
+                                          Checker.CheckContext theContext,
+                                          Catalog catalog) {
+
+        Map<String, Map> augs = (Map<String, Map>) theSpec.get(theFacet.name());
+        if (null == augs) {
+            return true;
+        }
+
+        boolean res = true;
+        if (theSpecType == null) {
+            theSpecType = (String) theSpec.get("type");
+        }
+        if (theSpecType == null) {
+            theContext.addError("No specification type available", null);
+            return false;
+        }
+
+        for (Iterator<Map.Entry<String, Map>> ai = augs.entrySet().iterator(); ai.hasNext(); ) {
+            Map.Entry<String, Map> ae = ai.next();
+
+            //make sure it was declared by the type
+            Map facetDef = catalog.getFacetDefinition(theConstruct, theSpecType, theFacet, ae.getKey());
+            if (facetDef == null) {
+                theContext.addError(UNKNOWN + theConstruct + " " + theFacet + " (not declared by the type " + theSpecType + ") were used: " + ae.getKey(), null);
+                res = false;
+                continue;
+            }
+
+            //check the compatibility of the augmentation: only the type cannot be changed
+            //can the type be changed in a compatible manner ??
+            if (!facetDef.get("type").equals(ae.getValue().get("type"))) {
+                theContext.addError(theConstruct + " " + theFacet + " " + ae.getKey() + " has a different type than its definition: " + ae.getValue().get("type") + " instead of " + facetDef.get("type"), null);
+                res = false;
+                continue;
+            }
+            DataCommon dataCommon = DataCommon.getInstance();
+            //check any valuation (here just defaults)
+            Object defaultValue = ae.getValue().get(DEFAULT);
+            if (defaultValue != null) {
+                dataCommon.checkDataValuation(defaultValue, ae.getValue(), theContext);
+            }
+        }
+
+        return res;
+    }
+
+    /*
+     * Checks the validity of a certain facet of a construct
+     * (properties of a node) across a type hierarchy.
+     * For now the check is limited to a verifying that a a facet was declared
+     * somewhere in the construct type hierarchy (a node template property has
+     * been declared in the node type hierarchy).
+     *
+     * 2 versions with the more generic allowing the specification of the type
+     * to be done explicitly.
+     */
+    public boolean checkFacet(Construct theConstruct,
+                               Map theSpec,
+                               Facet theFacet,
+                               Checker.CheckContext theContext,
+                               Catalog catalog) {
+        return checkFacet(theConstruct, theSpec, null, theFacet, theContext, catalog);
+    }
+
+    /**
+     * We walk the hierarchy and verify the assignment of a property with respect to its definition.
+     * We also collect the names of those properties defined as required but for which no assignment was provided.
+     */
+    public boolean checkFacet(Construct theConstruct,
+                               Map theSpec,
+                               String theSpecType,
+                               Facet theFacet,
+                               Checker.CheckContext theContext,
+                               Catalog catalog) {
+
+        Map<String, Map> defs = (Map<String, Map>) theSpec.get(theFacet.name());
+        if (null == defs) {
+            return true;
+        }
+        defs = Maps.newHashMap(defs); //
+
+        boolean res = true;
+        if (theSpecType == null) {
+            theSpecType = (String) theSpec.get("type");
+        }
+        if (theSpecType == null) {
+            theContext.addError("No specification type available", null);
+            return false;
+        }
+
+        Map<String, Byte> missed = new HashMap<>();  //keeps track of the missing required properties, the value is
+        //false if a default was found along the hierarchy
+        Iterator<Map.Entry<String, Map>> i =
+                catalog.hierarchy(theConstruct, theSpecType);
+        while (i.hasNext() && !defs.isEmpty()) {
+            Map.Entry<String, Map> type = i.next();
+
+            Map<String, Map> typeDefs = (Map<String, Map>) type.getValue()
+                    .get(theFacet.name());
+            if (null == typeDefs) {
+                continue;
+            }
+
+            MapDifference<String, Map> diff = Maps.difference(defs, typeDefs);
+
+            //this are the ones this type and the spec have in common (same key,
+            //different values)
+            Map<String, MapDifference.ValueDifference<Map>> facetDefs =
+                    diff.entriesDiffering();
+            //TODO: this assumes the definition of the facet is not cumulative, i.e.
+            //subtypes 'add' something to the definition provided by the super-types
+            //it considers the most specialized definition stands on its own
+            for (MapDifference.ValueDifference<Map> valdef : facetDefs.values()) {
+                DataCommon dataCommon = DataCommon.getInstance();
+                dataCommon.checkDataValuation(valdef.leftValue(), valdef.rightValue(), theContext);
+            }
+
+            //remove from properties all those that appear in this type: unfortunately this returns an unmodifiable map ..
+            defs = Maps.newHashMap(diff.entriesOnlyOnLeft());
+        }
+
+        if (!defs.isEmpty()) {
+            theContext.addError(UNKNOWN + theConstruct + " " + theFacet + " (not declared by the type " + theSpecType + ") were used: " + defs, null);
+            res = false;
+        }
+
+        if (!missed.isEmpty()) {
+            List missedNames =
+                    missed.entrySet()
+                            .stream()
+                            .filter(e -> e.getValue().byteValue() == (byte) 1)
+                            .map(e -> e.getKey())
+                            .collect(Collectors.toList());
+            if (!missedNames.isEmpty()) {
+                theContext.addError(theConstruct + " " + theFacet + " missing required values for: " + missedNames, null);
+                res = false;
+            }
+        }
+
+        return res;
+    }
+
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/GroupCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/GroupCommon.java
new file mode 100644
index 0000000..13ee692
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/GroupCommon.java
@@ -0,0 +1,118 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+
+public class GroupCommon extends BaseCommon{
+    private static GroupCommon instance;
+
+    public synchronized static GroupCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new GroupCommon();
+        }
+        return instance;
+    }
+
+    private GroupCommon() {}
+
+    public void checkGroupTypeDefinition(String theName,
+                                         Map theDefinition,
+                                         Checker.CheckContext theContext,
+                                         Catalog catalog) {
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName, Construct.Group);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Group, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+
+            if (theDefinition.containsKey(TARGETS_CONSTANT)) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog,
+                        ((List<String>) theDefinition.get(TARGETS_CONSTANT)).toArray(EMPTY_STRING_ARRAY));
+            }
+            InterfaceCommon interfaceCommon = InterfaceCommon.getInstance();
+            //interfaces
+            Map<String, Map> interfaces =
+                    (Map<String, Map>) theDefinition.get(INTERFACES);
+            interfaceCommon.checkMapTypeInterfaceDefinition(theContext, interfaces, catalog);
+
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkGroupDefinition(String theName,
+                                     Map theDef,
+                                     Checker.CheckContext theContext,
+                                     Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+
+            if (!typeCommon.checkType(Construct.Group, theDef, theContext, catalog)) {
+                return;
+            }
+
+            if (!facetCommon.checkFacet(
+                    Construct.Group, theDef, Facet.properties, theContext, catalog)) {
+                return;
+            }
+
+            if (theDef.containsKey(TARGETS_CONSTANT)) {
+
+                List<String> targetsTypes = (List<String>)
+                        catalog.getTypeDefinition(Construct.Group,
+                                (String) theDef.get("type"))
+                                .get(TARGETS_CONSTANT);
+
+                List<String> targets = (List<String>) theDef.get(TARGETS_CONSTANT);
+                for (String targetItr : targets) {
+                    if (!catalog.hasTemplate(theContext.target(), Construct.Node, targetItr)) {
+                        theContext.addError("The 'targets' entry must contain a reference to a node template, '" + targetItr + "' is not one", null);
+                    } else {
+                        if (targetsTypes != null) {
+                            String targetType = (String)
+                                    catalog.getTemplate(theContext.target(), Construct.Node, targetItr).get("type");
+
+                            boolean found = false;
+                            for (String type : targetsTypes) {
+                                found = catalog
+                                        .isDerivedFrom(Construct.Node, targetType, type);
+                                if (found) {
+                                    break;
+                                }
+                            }
+
+                            if (!found) {
+                                theContext.addError("The 'targets' entry '" + targetItr + "' is not type compatible with any of types specified in policy type targets", null);
+                            }
+                        }
+                    }
+                }
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InputsOutputsCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InputsOutputsCommon.java
new file mode 100644
index 0000000..04fd4b1
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InputsOutputsCommon.java
@@ -0,0 +1,66 @@
+package org.onap.sdc.dcae.checker.common;
+
+import kwalify.Rule;
+import kwalify.Validator;
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+import org.onap.sdc.dcae.checker.validation.TOSCAValidator;
+
+import java.util.Iterator;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.DEFAULT;
+
+public class InputsOutputsCommon extends BaseCommon {
+
+    private static InputsOutputsCommon instance;
+
+    public synchronized static InputsOutputsCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new InputsOutputsCommon();
+        }
+        return instance;
+    }
+
+    private InputsOutputsCommon() {}
+
+    public void checkInputDefinition(String theName,
+                                     Map theDef,
+                                     Checker.CheckContext theContext,
+                                     Catalog catalog) {
+        DataCommon dataCommon = DataCommon.getInstance();
+        theContext.enter(theName);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+            //
+            if (!dataCommon.checkDataType(theDef, theContext, catalog)) {
+                return;
+            }
+            //check default value
+            Object defaultValue = theDef.get(DEFAULT);
+            if (defaultValue != null) {
+                dataCommon.checkDataValuation(defaultValue, theDef, theContext);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+
+
+    public void checkOutputDefinition(String theName,
+                                       Map theDef,
+                                       Checker.CheckContext theContext) {
+        theContext.enter(theName);
+        try {
+            CheckCommon.getInstance().checkDefinition(theName, theDef, theContext);
+            //check the expression
+        } finally {
+            theContext.exit();
+        }
+    }
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InterfaceCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InterfaceCommon.java
new file mode 100644
index 0000000..3d7dfef
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/InterfaceCommon.java
@@ -0,0 +1,164 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Iterator;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.INPUTS;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.INTERFACES;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.WAS_DEFINED_FOR_THE_NODE_TYPE;
+
+public class InterfaceCommon extends BaseCommon {
+    private static InterfaceCommon instance;
+
+    public synchronized static void init(IChecker checker) {
+        if (instance == null)
+        {
+            instance = new InterfaceCommon();
+            instance.setChecker(checker);
+        }
+    }
+
+    public synchronized static InterfaceCommon getInstance() {
+        if (instance == null)
+        {
+            errLogger.log(LogLevel.ERROR, InterfaceCommon.class.getSimpleName(),"Need to call init before");
+        }
+        return instance;
+    }
+
+    private InterfaceCommon() {}
+
+    private IChecker checker;
+
+    //checking of actual constructs (capability, ..)
+
+    /* First, interface types do not have a hierarchical organization (no
+     * 'derived_from' in a interface type definition).
+     * So, when interfaces (with a certain type) are defined in a node
+     * or relationship type (and they can define new? operations), what
+     * is there to check:
+     * 	Can operations here re-define their declaration from the interface
+     * type spec?? From A.5.11.3 we are to understand indicates override to be
+     * the default interpretation .. but they talk about sub-classing so it
+     * probably intended as a reference to the node or relationship type
+     * hierarchy and not the interface type (no hierarchy there).
+     *	Or is this a a case of augmentation where new operations can be added??
+     */
+    public void check_type_interface_definition(
+            String theName, Map theDef, Checker.CheckContext theContext, Catalog catalog) {
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+
+            if (!typeCommon.checkType(Construct.Interface, theDef, theContext, catalog)) {
+                return;
+            }
+
+            if (theDef.containsKey(INPUTS)) {
+                checker.check_inputs((Map<String, Map>) theDef.get(INPUTS), theContext);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkTemplateInterfacesDefinition(
+            Map<String, Map> theInterfaces,
+            Checker.CheckContext theContext,
+            Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(INTERFACES);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(INTERFACES, theInterfaces, theContext)) {
+                return;
+            }
+
+            //the node type for the node template enclosing these requirements
+            String nodeType = (String) catalog.getTemplate(
+                    theContext.target(),
+                    Construct.Node,
+                    theContext.enclosingConstruct(Construct.Node))
+                    .get("type");
+
+            for (Iterator<Map.Entry<String, Map>> ii =
+                 theInterfaces.entrySet().iterator();
+                 ii.hasNext(); ) {
+
+                Map.Entry<String, Map> ie = ii.next();
+
+                String interfaceName = ie.getKey();
+                Map interfaceDef = facetCommon.findTypeFacetByName(Construct.Node, nodeType,
+                        Facet.interfaces, interfaceName, catalog);
+
+                if (interfaceDef == null) {
+                    /* this is subject to augmentation: this could be a warning but not an error */
+                    theContext.addError("No interface " + interfaceName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
+                    continue;
+                }
+
+                checkTemplateInterfaceDefinition(
+                        interfaceName, ie.getValue(), interfaceDef, theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkTemplateInterfaceDefinition(
+            String theInterfaceName,
+            Map theAssignment,
+            Map theDefinition,
+            Checker.CheckContext theContext,
+            Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(theInterfaceName, Construct.Interface);
+        try {
+            //check the assignment of the common inputs
+            facetCommon.checkFacet(Construct.Interface,
+                    theAssignment,
+                    (String) theDefinition.get("type"),
+                    Facet.inputs,
+                    theContext,
+                    catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkMapTypeInterfaceDefinition(Checker.CheckContext theContext, Map<String, Map> interfaces, Catalog catalog) {
+        if (interfaces != null) {
+            try {
+                theContext.enter(INTERFACES);
+                for (Iterator<Map.Entry<String, Map>> i =
+                     interfaces.entrySet().iterator(); i.hasNext(); ) {
+                    Map.Entry<String, Map> e = i.next();
+                    check_type_interface_definition(
+                            e.getKey(), e.getValue(), theContext, catalog);
+                }
+            } finally {
+                theContext.exit();
+            }
+        }
+    }
+
+    public void checkInterfaceTypeDefinition(String theName,
+                                              Map theDefinition,
+                                              Checker.CheckContext theContext) {
+        theContext.enter(theName, Construct.Interface);
+        try {
+            CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext);
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    void setChecker(IChecker checker) {
+        this.checker = checker;
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/NodeCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/NodeCommon.java
new file mode 100644
index 0000000..2fa9752
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/NodeCommon.java
@@ -0,0 +1,197 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+
+public class NodeCommon extends BaseCommon {
+
+    private static NodeCommon instance;
+
+    public synchronized static void init(IChecker checker) {
+        if (instance == null) {
+            instance = new NodeCommon();
+            instance.setChecker(checker);
+        }
+    }
+
+    public synchronized static NodeCommon getInstance() {
+        if (instance == null)
+        {
+            errLogger.log(LogLevel.ERROR, InterfaceCommon.class.getSimpleName(),"Need to call init before");
+        }
+        return instance;
+    }
+
+    private NodeCommon() {}
+
+    private IChecker checker;
+
+    public void checkNodeTypeDefinition(String theName,
+                                        Map theDefinition,
+                                        Checker.CheckContext theContext,
+                                        Catalog catalog) {
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        RequirementCommon requirementCommon = RequirementCommon.getInstance();
+        CapabilityCommon capabilityCommon = CapabilityCommon.getInstance();
+        InterfaceCommon interfaceCommon = InterfaceCommon.getInstance();
+        theContext.enter(theName, Construct.Node);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Node, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+
+            if (theDefinition.containsKey(ATTRIBUTES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Node, theName, theDefinition,
+                        Facet.attributes, theContext, catalog);
+            }
+
+            //requirements
+            if (theDefinition.containsKey(REQUIREMENTS)) {
+                requirementCommon.check_requirements(
+                        (List<Map>) theDefinition.get(REQUIREMENTS), theContext, catalog);
+            }
+
+            //capabilities
+            if (theDefinition.containsKey(CAPABILITIES)) {
+                capabilityCommon.check_capabilities(
+                        (Map<String, Map>) theDefinition.get(CAPABILITIES), theContext, catalog);
+            }
+
+            //interfaces:
+            Map<String, Map> interfaces =
+                    (Map<String, Map>) theDefinition.get(INTERFACES);
+            interfaceCommon.checkMapTypeInterfaceDefinition(theContext, interfaces, catalog);
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    /* */
+    public void checkNodeTemplateDefinition(String theName,
+                                             Map theNode,
+                                             Checker.CheckContext theContext,
+                                             Catalog catalog) {
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        RequirementCommon requirementCommon = RequirementCommon.getInstance();
+        CapabilityCommon capabilityCommon = CapabilityCommon.getInstance();
+        InterfaceCommon interfaceCommon = InterfaceCommon.getInstance();
+        theContext.enter(theName, Construct.Node);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theNode, theContext)) {
+                return;
+            }
+
+            if (!typeCommon.checkType(Construct.Node, theNode, theContext, catalog)) {
+                return;
+            }
+
+            //copy
+            String copy = (String) theNode.get("copy");
+            if (copy != null) {
+                if (!typeCommon.checkTemplateReference(Construct.Node, theContext, catalog, copy)) {
+                    theContext.addError("The 'copy' reference " + copy + " does not point to a known node template", null);
+                } else {
+                    //the 'copy' node specification should be used to provide 'defaults'
+                    //for this specification
+                }
+            }
+
+      /* check that we operate on properties and attributes within the scope of
+        the specified node type */
+            if (!facetCommon.checkFacet(
+                    Construct.Node, /*theName,*/theNode, Facet.properties, theContext, catalog)) {
+                return;
+            }
+
+            if (!facetCommon.checkFacet(
+                    Construct.Node, /*theName,*/theNode, Facet.attributes, theContext, catalog)) {
+                return;
+            }
+
+            //requirement assignment seq
+            if (theNode.containsKey(REQUIREMENTS)) {
+                requirementCommon.checkRequirementsAssignmentDefinition(
+                        (List<Map>) theNode.get(REQUIREMENTS), theContext, catalog);
+            }
+
+            //capability assignment map: subject to augmentation
+            if (theNode.containsKey(CAPABILITIES)) {
+                capabilityCommon.checkCapabilitiesAssignmentDefinition(
+                        (Map<String, Map>) theNode.get(CAPABILITIES), theContext, catalog);
+            }
+
+            //interfaces
+            if (theNode.containsKey(INTERFACES)) {
+                interfaceCommon.checkTemplateInterfacesDefinition(
+                        (Map<String, Map>) theNode.get(INTERFACES), theContext, catalog);
+            }
+
+            //artifacts: artifacts do not have different definition forms/syntax
+            //depending on the context (type or template) but they are still subject
+            //to 'augmentation'
+            if (theNode.containsKey(ARTIFACTS)) {
+                checker.check_template_artifacts_definition(
+                        (Map<String, Object>) theNode.get(ARTIFACTS), theContext);
+            }
+
+            /* node_filter: the context to which the node filter is applied is very
+             * wide here as opposed to the node filter specification in a requirement
+             * assignment which has a more strict context (target node/capability are
+             * specified).
+             * We could check that there are nodes in this template having the
+             * properties/capabilities specified in this filter, i.e. the filter has
+             * a chance to succeed.
+             */
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    /* Requirements are the odd ball as they are structured as a sequence .. */
+    public Map<String, Map> findNodeTypeRequirementByName(
+            String theNodeType, String theRequirementName, Catalog catalog) {
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findNodeTypeRequirementByName {}/{}", theNodeType, theRequirementName);
+        Iterator<Map.Entry<String, Map>> i =
+                catalog.hierarchy(Construct.Node, theNodeType);
+        while (i.hasNext()) {
+            Map.Entry<String, Map> nodeType = i.next();
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "findNodeTypeRequirementByName, Checking node type {}", nodeType.getKey());
+            List<Map<String, Map>> nodeTypeRequirements =
+                    (List<Map<String, Map>>) nodeType.getValue().get(REQUIREMENTS);
+            if (nodeTypeRequirements == null) {
+                continue;
+            }
+
+            for (Map<String, Map> requirement : nodeTypeRequirements) {
+                Map requirementDef = requirement.get(theRequirementName);
+                if (requirementDef != null) {
+                    return requirementDef;
+                }
+            }
+        }
+        return null;
+    }
+
+    public void setChecker(IChecker checker) {
+        this.checker = checker;
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PolicyCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PolicyCommon.java
new file mode 100644
index 0000000..9c1d8cd
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PolicyCommon.java
@@ -0,0 +1,134 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.IS_NONE_OF_THOSE;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.PROPERTIES;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.TARGETS_CONSTANT;
+
+public class PolicyCommon extends BaseCommon {
+
+    private static PolicyCommon instance;
+
+    public synchronized static PolicyCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new PolicyCommon();
+        }
+        return instance;
+    }
+
+    private PolicyCommon() {}
+
+
+    public void checkPolicyTypeDefinition(String theName,
+                                          Map theDefinition,
+                                          Checker.CheckContext theContext,
+                                          Catalog catalog,
+                                          Target target) {
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(theName, Construct.Policy);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Policy, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+
+            //the targets can be known node types or group types
+            List<String> targets = (List<String>) theDefinition.get(TARGETS_CONSTANT);
+            if ((targets != null) && (CheckCommon.getInstance().checkDefinition(TARGETS_CONSTANT, targets, theContext))) {
+                for (String targetItr : targets) {
+                    if (!(catalog.hasType(Construct.Node, targetItr) ||
+                            catalog.hasType(Construct.Group, targetItr))) {
+                        theContext.addError("The 'targets' entry must contain a reference to a node type or group type, '" + target + IS_NONE_OF_THOSE, null);
+                    }
+                }
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkPolicyDefinition(String theName,
+                                      Map theDef,
+                                      Checker.CheckContext theContext,
+                                      Catalog catalog,
+                                      Target target)
+    {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+
+        theContext.enter(theName);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+
+            if (!typeCommon.checkType(Construct.Policy, theDef, theContext, catalog)) {
+                return;
+            }
+
+            if (!facetCommon.checkFacet(Construct.Policy, theDef, Facet.properties, theContext, catalog)) {
+                return;
+            }
+
+            //targets: must point to node or group templates (that are of a type
+            //specified in the policy type definition, if targets were specified
+            //there).
+            if (theDef.containsKey(TARGETS_CONSTANT)) {
+                List<String> targetsTypes = (List<String>)
+                        catalog.getTypeDefinition(Construct.Policy,
+                                (String) theDef.get("type"))
+                                .get(TARGETS_CONSTANT);
+
+                List<String> targets = (List<String>) theDef.get(TARGETS_CONSTANT);
+                for (String targetItr : targets) {
+                    Construct targetConstruct = null;
+
+                    if (catalog.hasTemplate(theContext.target(), Construct.Group, targetItr)) {
+                        targetConstruct = Construct.Group;
+                    } else if (catalog.hasTemplate(theContext.target(), Construct.Node, targetItr)) {
+                        targetConstruct = Construct.Node;
+                    } else {
+                        theContext.addError("The 'targets' entry must contain a reference to a node template or group template, '" + target + IS_NONE_OF_THOSE, null);
+                    }
+
+                    if (targetConstruct != null &&
+                            targetsTypes != null) {
+                        //get the target type and make sure is compatible with the types
+                        //indicated in the type spec
+                        String targetType = (String)
+                                catalog.getTemplate(theContext.target(), targetConstruct, targetItr).get("type");
+
+                        boolean found = false;
+                        for (String type : targetsTypes) {
+                            found = catalog
+                                    .isDerivedFrom(targetConstruct, targetType, type);
+                            if (found) {
+                                break;
+                            }
+                        }
+
+                        if (!found) {
+                            theContext.addError("The 'targets' " + targetConstruct + " entry '" + targetItr + "' is not type compatible with any of types specified in policy type targets", null);
+                        }
+                    }
+                }
+            }
+
+        } finally {
+            theContext.exit();
+        }
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PropertiesCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PropertiesCommon.java
new file mode 100644
index 0000000..f19e19b
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/PropertiesCommon.java
@@ -0,0 +1,97 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.Catalog;
+import org.onap.sdc.dcae.checker.Checker;
+import org.onap.sdc.dcae.checker.IChecker;
+
+import java.util.Iterator;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.DEFAULT;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.PROPERTIES;
+
+public class PropertiesCommon extends BaseCommon {
+
+    private static PropertiesCommon instance;
+
+    public synchronized static PropertiesCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new PropertiesCommon();
+        }
+        return instance;
+    }
+
+    private PropertiesCommon() {}
+
+    public void checkProperties(
+            Map<String, Map> theDefinitions, Checker.CheckContext theContext, Catalog catalog) {
+        theContext.enter(PROPERTIES);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(PROPERTIES, theDefinitions, theContext)) {
+                return;
+            }
+
+            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext(); ) {
+                Map.Entry<String, Map> e = i.next();
+                checkPropertyDefinition(e.getKey(), e.getValue(), theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    private void checkPropertyDefinition(
+            String theName, Map theDefinition, Checker.CheckContext theContext, Catalog catalog) {
+        DataCommon dataCommon = DataCommon.getInstance();
+        theContext.enter(theName);
+        if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+            return;
+        }
+        //check the type
+        if (!dataCommon.checkDataType(theDefinition, theContext, catalog)) {
+            return;
+        }
+        //check default value is compatible with type
+        Object defaultValue = theDefinition.get(DEFAULT);
+        if (defaultValue != null) {
+            dataCommon.checkDataValuation(defaultValue, theDefinition, theContext);
+        }
+
+        theContext.exit();
+    }
+
+    public void check_property_definition(String theName, Map theDefinition, Checker.CheckContext theContext, Catalog catalog) {
+        DataCommon dataCommon = DataCommon.getInstance();
+        theContext.enter(theName);
+        if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+            return;
+        }
+        // check the type
+        if (!dataCommon.checkDataType(theDefinition, theContext, catalog)) {
+            return;
+        }
+        // check default value is compatible with type
+        Object defaultValue = theDefinition.get("default");
+        if (defaultValue != null) {
+            dataCommon.checkDataValuation(defaultValue, theDefinition, theContext);
+        }
+
+        theContext.exit();
+    }
+
+    public void check_properties(Map<String, Map> theDefinitions, Checker.CheckContext theContext, Catalog catalog) {
+        theContext.enter("properties");
+        try {
+            if (!CheckCommon.getInstance().checkDefinition("properties", theDefinitions, theContext))
+                return;
+
+            for (Iterator<Map.Entry<String, Map>> i = theDefinitions.entrySet().iterator(); i.hasNext();) {
+                Map.Entry<String, Map> e = i.next();
+                check_property_definition(e.getKey(), e.getValue(), theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RelationshipCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RelationshipCommon.java
new file mode 100644
index 0000000..145873a
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RelationshipCommon.java
@@ -0,0 +1,112 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.EMPTY_STRING_ARRAY;
+import static org.onap.sdc.dcae.checker.common.ConstCommon.VALID_TARGET_TYPES;
+
+public class RelationshipCommon extends BaseCommon {
+    private static RelationshipCommon instance;
+
+    public synchronized static RelationshipCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new RelationshipCommon();
+        }
+        return instance;
+    }
+
+    private RelationshipCommon() {}
+
+    public void checkRelationshipTypeDefinition(String theName,
+                                                Map theDefinition,
+                                                Checker.CheckContext theContext,
+                                                Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        PropertiesCommon propertiesCommon = PropertiesCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        InterfaceCommon interfaceCommon = InterfaceCommon.getInstance();
+        theContext.enter(theName, Construct.Relationship);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDefinition, theContext)) {
+                return;
+            }
+
+            if (theDefinition.containsKey(PROPERTIES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(PROPERTIES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Relationship, theName, theDefinition,
+                        Facet.properties, theContext, catalog);
+            }
+
+            if (theDefinition.containsKey(ATTRIBUTES)) {
+                propertiesCommon.checkProperties(
+                        (Map<String, Map>) theDefinition.get(ATTRIBUTES), theContext, catalog);
+                facetCommon.checkTypeConstructFacet(Construct.Relationship, theName, theDefinition,
+                        Facet.attributes, theContext, catalog);
+            }
+
+            Map<String, Map> interfaces = (Map<String, Map>) theDefinition.get(INTERFACES);
+            if (interfaces != null) {
+                theContext.enter(INTERFACES);
+                for (Iterator<Map.Entry<String, Map>> i =
+                     interfaces.entrySet().iterator(); i.hasNext(); ) {
+                    Map.Entry<String, Map> e = i.next();
+                    interfaceCommon.check_type_interface_definition(
+                            e.getKey(), e.getValue(), theContext, catalog);
+                }
+                theContext.exit();
+            }
+
+            if (theDefinition.containsKey(VALID_TARGET_TYPES)) {
+                typeCommon.checkTypeReference(Construct.Capability, theContext , catalog,
+                        ((List<String>) theDefinition.get(VALID_TARGET_TYPES)).toArray(EMPTY_STRING_ARRAY));
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkRelationshipTemplateDefinition(
+            String theName,
+            Map theRelationship,
+            Checker.CheckContext theContext,
+            Catalog catalog) {
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        theContext.enter(theName, Construct.Relationship);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theRelationship, theContext)) {
+                return;
+            }
+
+            if (!typeCommon.checkType(Construct.Relationship, theRelationship, theContext, catalog)) {
+                return;
+            }
+
+      /* check that we operate on properties and attributes within the scope of
+        the specified relationship type */
+            if (!facetCommon.checkFacet(Construct.Relationship, theRelationship,
+                    Facet.properties, theContext, catalog)) {
+                return;
+            }
+
+            if (!facetCommon.checkFacet(Construct.Relationship, theRelationship,
+                    Facet.attributes, theContext, catalog)) {
+                return;
+            }
+
+    /* interface definitions
+           note: augmentation is allowed here so not clear what to check ..
+             maybe report augmentations if so configured .. */
+
+        } finally {
+            theContext.exit();
+        }
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RequirementCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RequirementCommon.java
new file mode 100644
index 0000000..ff2c2f2
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/RequirementCommon.java
@@ -0,0 +1,464 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.apache.commons.jxpath.JXPathContext;
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.*;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+
+public class RequirementCommon extends BaseCommon {
+
+    private static RequirementCommon instance;
+
+    public synchronized static RequirementCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new RequirementCommon();
+        }
+        return instance;
+    }
+
+    private RequirementCommon() {}
+
+    public void check_requirements(List<Map> theDefinition,
+                                   Checker.CheckContext theContext,
+                                   Catalog catalog) {
+        theContext.enter(REQUIREMENTS);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(REQUIREMENTS, theDefinition, theContext)) {
+                return;
+            }
+
+            for (Iterator<Map> i = theDefinition.iterator(); i.hasNext(); ) {
+                Map e = i.next();
+                Iterator<Map.Entry<String, Map>> ei =
+                        (Iterator<Map.Entry<String, Map>>) e.entrySet().iterator();
+                Map.Entry<String, Map> eie = ei.next();
+                checkRequirementDefinition(eie.getKey(), eie.getValue(), theContext, catalog);
+                assert !ei.hasNext();
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkRequirementDefinition(String theName,
+                                            Map theDef,
+                                            Checker.CheckContext theContext,
+                                            Catalog catalog) {
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext.enter(theName, Construct.Requirement);
+
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(theName, theDef, theContext)) {
+                return;
+            }
+            //check capability type
+            String capabilityType = (String) theDef.get(CAPABILITY);
+            if (null != capabilityType) {
+                typeCommon.checkTypeReference(Construct.Capability, theContext, catalog, capabilityType);
+            }
+
+            //check node type
+            String nodeType = (String) theDef.get("node");
+            if (null != nodeType) {
+                typeCommon.checkTypeReference(Construct.Node, theContext, catalog, nodeType);
+            }
+
+            //check relationship type
+            Map relationshipSpec = (Map) theDef.get("relationship");
+            String relationshipType = null;
+            if (null != relationshipSpec) {
+                relationshipType = (String) relationshipSpec.get("type");
+                if (relationshipType != null) { //should always be the case
+                    typeCommon.checkTypeReference(Construct.Relationship, theContext, catalog, relationshipType);
+                }
+
+                Map<String, Map> interfaces = (Map<String, Map>)
+                        relationshipSpec.get(INTERFACES);
+                if (interfaces != null) {
+                    //augmentation (additional properties or operations) of the interfaces
+                    //defined by the above relationship types
+
+                    //check that the interface types are known
+                    for (Map interfaceDef : interfaces.values()) {
+                        typeCommon.checkType(Construct.Interface, interfaceDef, theContext, catalog);
+                    }
+                }
+            }
+
+            //cross checks
+
+            //the capability definition might come from the capability type or from the capability definition
+            //within the node type. We might have more than one as a node might specify multiple capabilities of the
+            //same type.
+            //the goal here is to cross check the compatibility of the valid_source_types specification in the
+            //target capability definition (if that definition contains a valid_source_types entry).
+            List<Map> capabilityDefs = new LinkedList<>();
+            //nodeType exposes capabilityType
+            if (nodeType != null) {
+                Map<String, Map> capabilities =
+                        facetCommon.findTypeFacetByType(Construct.Node, nodeType,
+                                Facet.capabilities, capabilityType, catalog);
+                if (capabilities.isEmpty()) {
+                    theContext.addError("The node type " + nodeType + " does not appear to expose a capability of a type compatible with " + capabilityType, null);
+                } else {
+                    for (Map.Entry<String, Map> capability : capabilities.entrySet()) {
+                        //this is the capability as it was defined in the node type
+                        Map capabilityDef = capability.getValue();
+                        //if it defines a valid_source_types then we're working with it,
+                        //otherwise we're working with the capability type it points to.
+                        //The spec does not make it clear if the valid_source_types in a capability definition augments or
+                        //overwrites the one from the capabilityType (it just says they must be compatible).
+                        if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
+                            capabilityDefs.add(capabilityDef);
+                        } else {
+                            capabilityDef =
+                                    catalog.getTypeDefinition(Construct.Capability, (String) capabilityDef.get("type"));
+                            if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
+                                capabilityDefs.add(capabilityDef);
+                            } else {
+                                //!!if there is a capability that does not have a valid_source_type than there is no reason to
+                                //make any further verification (as there is a valid node_type/capability target for this requirement)
+                                capabilityDefs.clear();
+                                break;
+                            }
+                        }
+                    }
+                }
+            } else {
+                Map capabilityDef = catalog.getTypeDefinition(Construct.Capability, capabilityType);
+                if (capabilityDef.containsKey(VALID_SOURCE_TYPES)) {
+                    capabilityDefs.add(capabilityDef);
+                }
+            }
+
+            //check that the node type enclosing this requirement definition
+            //is in the list of valid_source_types
+            if (!capabilityDefs.isEmpty()) {
+                String enclosingNodeType =
+                        theContext.enclosingConstruct(Construct.Node);
+                assert enclosingNodeType != null;
+
+                if (!capabilityDefs.stream().anyMatch(
+                        (Map capabilityDef) -> {
+                            List<String> valid_source_types =
+                                    (List<String>) capabilityDef.get(VALID_SOURCE_TYPES);
+                            return valid_source_types.stream().anyMatch(
+                                    (String source_type) -> catalog.isDerivedFrom(
+                                            Construct.Node, enclosingNodeType, source_type));
+                        })) {
+                    theContext.addError("Node type: " + enclosingNodeType + " not compatible with any of the valid_source_types provided in the definition of compatible capabilities", null);
+                }
+            }
+
+            //if we have a relationship type, check if it has a valid_target_types
+            //if it does, make sure that the capability type is compatible with one
+            //of them
+            if (relationshipType != null) { //should always be the case
+                Map relationshipTypeDef = catalog.getTypeDefinition(
+                        Construct.Relationship, relationshipType);
+                if (relationshipTypeDef != null) {
+                    List<String> valid_target_types =
+                            (List<String>) relationshipTypeDef.get(VALID_TARGET_TYPES);
+                    if (valid_target_types != null) {
+                        boolean found = false;
+                        for (String target_type : valid_target_types) {
+                            if (catalog.isDerivedFrom(
+                                    Construct.Capability, capabilityType, target_type)) {
+                                found = true;
+                                break;
+                            }
+                        }
+                        if (!found) {
+                            theContext.addError("Capability type: " + capabilityType + " not compatible with any of the valid_target_types " + valid_target_types + " provided in the definition of relationship type " + relationshipType, null);
+                        }
+                    }
+                }
+            }
+
+            //relationship declares the capabilityType in its valid_target_type set
+            //in A.6.9 'Relationship Type' the spec does not indicate how	inheritance
+            //is to be applied to the valid_target_type spec: cumulative, overwrites,
+            //so we treat it as an overwrite.
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    //requirements and capabilities assignment appear in a node templates
+    public void checkRequirementsAssignmentDefinition(
+            List<Map> theRequirements, Checker.CheckContext theContext, Catalog catalog) {
+        NodeCommon nodeCommon = NodeCommon.getInstance();
+        theContext.enter(REQUIREMENTS);
+        try {
+            if (!CheckCommon.getInstance().checkDefinition(REQUIREMENTS, theRequirements, theContext)) {
+                return;
+            }
+
+            //the node type for the node template enclosing these requirements
+            String nodeType = (String) catalog.getTemplate(
+                    theContext.target(),
+                    Construct.Node,
+                    theContext.enclosingConstruct(Construct.Node))
+                    .get("type");
+
+            for (Iterator<Map> ri = theRequirements.iterator(); ri.hasNext(); ) {
+                Map<String, Map> requirement = (Map<String, Map>) ri.next();
+
+                Iterator<Map.Entry<String, Map>> rai = requirement.entrySet().iterator();
+
+                Map.Entry<String, Map> requirementEntry = rai.next();
+                assert !rai.hasNext();
+
+                String requirementName = requirementEntry.getKey();
+                Map requirementDef = nodeCommon.findNodeTypeRequirementByName(
+                        nodeType, requirementName, catalog);
+
+                if (requirementDef == null) {
+                    theContext.addError("No requirement " + requirementName + WAS_DEFINED_FOR_THE_NODE_TYPE + nodeType, null);
+                    continue;
+                }
+
+                checkRequirementAssignmentDefinition(
+                        requirementName, requirementEntry.getValue(), requirementDef, theContext, catalog);
+            }
+        } finally {
+            theContext.exit();
+        }
+    }
+
+    public void checkRequirementAssignmentDefinition(
+            String theRequirementName,
+            Map theAssignment,
+            Map theDefinition,
+            Checker.CheckContext theContext,
+            Catalog catalog) {
+        TypeCommon typeCommon = TypeCommon.getInstance();
+        FacetCommon facetCommon = FacetCommon.getInstance();
+        theContext//.enter("requirement_assignment")
+                .enter(theRequirementName, Construct.Requirement);
+
+        //grab the node type definition to verify compatibility
+
+        try {
+            //node assignment
+            boolean targetNodeIsTemplate = false;
+            String targetNode = (String) theAssignment.get("node");
+            if (targetNode == null) {
+                targetNode = (String) theDefinition.get("node");
+                //targetNodeIsTemplate stays false, targetNode must be a type
+            } else {
+                //the value must be a node template or a node type
+                targetNodeIsTemplate = typeCommon.isTemplateReference(
+                        Construct.Node, theContext, targetNode, catalog);
+                if ((!targetNodeIsTemplate) && (!typeCommon.isTypeReference(Construct.Node, targetNode, catalog))){
+                    theContext.addError("The 'node' entry must contain a reference to a node template or node type, '" + targetNode + IS_NONE_OF_THOSE, null);
+                    return;
+                }
+
+                //additional checks
+                String targetNodeDef = (String) theDefinition.get("node");
+                if (targetNodeDef != null && targetNode != null) {
+                    if (targetNodeIsTemplate) {
+                        //if the target is node template, it must be compatible with the
+                        //node type specification in the requirement defintion
+                        String targetNodeType = (String)
+                                catalog.getTemplate(theContext.target(), Construct.Node, targetNode).get("type");
+                        if (!catalog.isDerivedFrom(
+                                Construct.Node, targetNodeType, targetNodeDef)) {
+                            theContext.addError("The required target node type '" + targetNodeType + "' of target node " + targetNode + " is not compatible with the target node type found in the requirement definition: " + targetNodeDef, null);
+                            return;
+                        }
+                    } else {
+                        //if the target is a node type it must be compatible (= or derived
+                        //from) with the node type specification in the requirement definition
+                        if (!catalog.isDerivedFrom(
+                                Construct.Node, targetNode, targetNodeDef)) {
+                            theContext.addError("The required target node type '" + targetNode + "' is not compatible with the target node type found in the requirement definition: " + targetNodeDef, null);
+                            return;
+                        }
+                    }
+                }
+            }
+
+            String targetNodeType = targetNodeIsTemplate ?
+                    (String) catalog.getTemplate(theContext.target(), Construct.Node, targetNode).get("type") :
+                    targetNode;
+
+            //capability assignment
+            boolean targetCapabilityIsType = false;
+            String targetCapability = (String) theAssignment.get(CAPABILITY);
+            if (targetCapability == null) {
+                targetCapability = (String) theDefinition.get(CAPABILITY);
+                //in a requirement definition the target capability can only be a
+                //capability type (and not a capability name within some target node
+                //type)
+                targetCapabilityIsType = true;
+            } else {
+                targetCapabilityIsType = typeCommon.isTypeReference(Construct.Capability, targetCapability, catalog);
+
+                //check compatibility with the target compatibility type specified
+                //in the requirement definition, if any
+                String targetCapabilityDef = (String) theDefinition.get(CAPABILITY);
+                if (targetCapabilityDef != null && targetCapability != null) {
+                    if (targetCapabilityIsType) {
+                        if (!catalog.isDerivedFrom(
+                                Construct.Capability, targetCapability, targetCapabilityDef)) {
+                            theContext.addError("The required target capability type '" + targetCapability + "' is not compatible with the target capability type found in the requirement definition: " + targetCapabilityDef, null);
+                            return;
+                        }
+                    } else {
+                        //the capability is from a target node. Find its definition and
+                        //check that its type is compatible with the capability type
+                        //from the requirement definition
+
+                        //check target capability compatibility with target node
+                        if (targetNode == null) {
+                            theContext.addError("The capability '" + targetCapability + "' is not a capability type, hence it has to be a capability of the node template indicated in 'node', which was not specified", null);
+                            return;
+                        }
+                        if (!targetNodeIsTemplate) {
+                            theContext.addError("The capability '" + targetCapability + "' is not a capability type, hence it has to be a capability of the node template indicated in 'node', but there you specified a node type", null);
+                            return;
+                        }
+                        //check that the targetNode (its type) indeed has the
+                        //targetCapability
+
+                        Map<String, Object> targetNodeCapabilityDef =
+                                facetCommon.findTypeFacetByName(
+                                        Construct.Node, targetNodeType,
+                                        Facet.capabilities, targetCapability, catalog);
+                        if (targetNodeCapabilityDef == null) {
+                            theContext.addError("No capability '" + targetCapability + "' was specified in the node " + targetNode + " of type " + targetNodeType, null);
+                            return;
+                        }
+
+                        String targetNodeCapabilityType = (String) targetNodeCapabilityDef.get("type");
+
+                        if (!catalog.isDerivedFrom(Construct.Capability,
+                                targetNodeCapabilityType,
+                                targetCapabilityDef)) {
+                            theContext.addError("The required target capability type '" + targetCapabilityDef + "' is not compatible with the target capability type found in the target node type capability definition : " + targetNodeCapabilityType + ", targetNode " + targetNode + ", capability name " + targetCapability, null);
+                            return;
+                        }
+                    }
+                }
+            }
+
+            //relationship assignment
+            Map targetRelationship = (Map) theAssignment.get("relationship");
+            if (targetRelationship != null) {
+                //this has to be compatible with the relationship with the same name
+                //from the node type
+                //check the type
+            }
+
+            //node_filter; used jxpath to simplify the navigation somewhat
+            //this is too cryptic
+            JXPathContext jxPath = JXPathContext.newContext(theAssignment);
+            jxPath.setLenient(true);
+
+            List<Map> propertiesFilter =
+                    (List<Map>) jxPath.getValue("/node_filter/properties");
+            if (propertiesFilter != null) {
+                for (Map propertyFilter : propertiesFilter) {
+                    if (targetNode != null) {
+                        //if we have a target node or node template then it must have
+                        //have these properties
+                        for (Object propertyName : propertyFilter.keySet()) {
+                            if (null == facetCommon.findTypeFacetByName(Construct.Node,
+                                    targetNodeType,
+                                    Facet.properties,
+                                    propertyName.toString(),
+                                    catalog)) {
+                                theContext.addError("The node_filter property " + propertyName + " is invalid: requirement target node " + targetNode + " does not have such a property", null);
+                            }
+                        }
+                    }
+                }
+            }
+
+            List<Map> capabilitiesFilter =
+                    (List<Map>) jxPath.getValue("node_filter/capabilities");
+            if (capabilitiesFilter != null) {
+                for (Map capabilityFilterDef : capabilitiesFilter) {
+                    assert capabilityFilterDef.size() == 1;
+                    Map.Entry<String, Map> capabilityFilterEntry =
+                            (Map.Entry<String, Map>) capabilityFilterDef.entrySet().iterator().next();
+                    String targetFilterCapability = capabilityFilterEntry.getKey();
+                    Map<String, Object> targetFilterCapabilityDef = null;
+
+                    //if we have a targetNode capabilityName must be a capability of
+                    //that node (type); or it can be simply capability type (but the node
+                    //must have a capability of that type)
+
+                    String targetFilterCapabilityType = null;
+                    if (targetNode != null) {
+                        targetFilterCapabilityDef =
+                                facetCommon.findTypeFacetByName(Construct.Node, targetNodeType,
+                                        Facet.capabilities, targetFilterCapability, catalog);
+                        if (targetFilterCapabilityDef != null) {
+                            targetFilterCapabilityType =
+                                    (String) targetFilterCapabilityDef/*.values().iterator().next()*/.get("type");
+                        } else {
+                            Map<String, Map> targetFilterCapabilities =
+                                    facetCommon.findTypeFacetByType(Construct.Node, targetNodeType,
+                                            Facet.capabilities, targetFilterCapability, catalog);
+
+                            if (!targetFilterCapabilities.isEmpty()) {
+                                if (targetFilterCapabilities.size() > 1) {
+                                    errLogger.log(LogLevel.WARN, this.getClass().getName(), "checkRequirementAssignmentDefinition: filter check, target node type '{}' has more than one capability of type '{}', not supported", targetNodeType, targetFilterCapability);
+                                }
+                                //pick the first entry, it represents a capability of the required type
+                                Map.Entry<String, Map> capabilityEntry = targetFilterCapabilities.entrySet().iterator().next();
+                                targetFilterCapabilityDef = Collections.singletonMap(capabilityEntry.getKey(),
+                                        capabilityEntry.getValue());
+                                targetFilterCapabilityType = targetFilterCapability;
+                            }
+                        }
+                    } else {
+                        //no node (type) specified, it can be a straight capability type
+                        targetFilterCapabilityDef = catalog.getTypeDefinition(
+                                Construct.Capability, targetFilterCapability);
+                        //here comes the odd part: it can still be a just a name in which
+                        //case we should look at the requirement definition, see which
+                        //capability (type) it indicates
+                        assert targetCapabilityIsType; //cannot be otherwise, we'd need a node
+                        targetFilterCapabilityDef = catalog.getTypeDefinition(
+                                Construct.Capability, targetCapability);
+                        targetFilterCapabilityType = targetCapability;
+                    }
+
+                    if (targetFilterCapabilityDef == null) {
+                        theContext.addError("Capability (name or type) " + targetFilterCapability + " is invalid: not a known capability (type) " +
+                                ((targetNodeType != null) ? (" of node type" + targetNodeType) : ""), null);
+                        continue;
+                    }
+
+                    for (Map propertyFilter :
+                            (List<Map>) jxPath.getValue("/node_filter/capabilities/" + targetFilterCapability + "/properties")) {
+                        //check that the properties are in the scope of the
+                        //capability definition
+                        for (Object propertyName : propertyFilter.keySet()) {
+                            if (null == facetCommon.findTypeFacetByName(Construct.Capability,
+                                    targetCapability,
+                                    Facet.properties,
+                                    propertyName.toString(),
+                                    catalog)) {
+                                theContext.addError("The capability filter " + targetFilterCapability + " property " + propertyName + " is invalid: target capability " + targetFilterCapabilityType + " does not have such a property", null);
+                            }
+                        }
+                    }
+                }
+            }
+
+        } finally {
+            theContext.exit();
+        }
+    }
+
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/TypeCommon.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/TypeCommon.java
new file mode 100644
index 0000000..9fb4226
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/common/TypeCommon.java
@@ -0,0 +1,115 @@
+package org.onap.sdc.dcae.checker.common;
+
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.dcae.checker.*;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static org.onap.sdc.dcae.checker.common.ConstCommon.*;
+
+public class TypeCommon extends BaseCommon {
+
+    private static TypeCommon instance;
+
+    public synchronized static TypeCommon getInstance() {
+        if (instance == null)
+        {
+            instance = new TypeCommon();
+        }
+        return instance;
+    }
+
+    private TypeCommon() {}
+
+    public boolean catalogTypes(Construct theConstruct, Map<String, Map> theTypes, Checker.CheckContext theContext, Catalog catalog) {
+
+        boolean res = true;
+        for (Map.Entry<String, Map> typeEntry : theTypes.entrySet()) {
+            res &= catalogType(theConstruct, typeEntry.getKey(), typeEntry.getValue(), theContext, catalog);
+        }
+
+        return res;
+    }
+
+    public boolean catalogType(Construct theConstruct,
+                                String theName,
+                                Map theDef,
+                                Checker.CheckContext theContext,
+                                Catalog catalog) {
+
+        if (!catalog.addType(theConstruct, theName, theDef)) {
+            theContext.addError(theConstruct + TYPE + theName + " re-declaration", null);
+            return false;
+        }
+        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "{} type {} has been cataloged", theConstruct, theName);
+
+        String parentType = (String) theDef.get("derived_from");
+        if (parentType != null && !catalog.hasType(theConstruct, parentType)) {
+            theContext.addError(
+                    theConstruct + TYPE + theName + " indicates a supertype that has not (yet) been declared: " + parentType, null);
+            return false;
+        }
+        return true;
+    }
+
+    public boolean checkTypeReference(Construct theConstruct,
+                                       Checker.CheckContext theContext,
+                                       Catalog catalog,
+                                       String... theTypeNames) {
+        boolean res = true;
+        for (String typeName : theTypeNames) {
+            if (!isTypeReference(theConstruct, typeName, catalog)) {
+                theContext.addError("Reference to " + theConstruct + " type '" + typeName + "' points to unknown type", null);
+                res = false;
+            }
+        }
+        return res;
+    }
+
+    public boolean isTypeReference(Construct theConstruct,
+                                   String theTypeName, Catalog catalog) {
+        return catalog.hasType(theConstruct, theTypeName);
+    }
+
+    //generic checking actions, not related to validation rules
+
+    /* will check the validity of the type specification for any construct containing a 'type' entry */
+    public boolean checkType(Construct theCategory, Map theSpec, Checker.CheckContext theContext, Catalog catalog) {
+        String type = (String) theSpec.get("type");
+        if (type == null) {
+            theContext.addError("Missing type specification", null);
+            return false;
+        }
+
+        if (!catalog.hasType(theCategory, type)) {
+            theContext.addError(UNKNOWN + theCategory + " type: " + type, null);
+            return false;
+        }
+
+        return true;
+    }
+
+    /* node or relationship templates */
+    public boolean checkTemplateReference(Construct theConstruct,
+                                           Checker.CheckContext theContext,
+                                           Catalog catalog,
+                                           String... theTemplateNames) {
+        boolean res = true;
+        for (String templateName : theTemplateNames) {
+            if (!isTemplateReference(theConstruct, theContext, templateName, catalog)) {
+                theContext.addError("Reference to " + theConstruct + " template '" + templateName + "' points to unknown template", null);
+                res = false;
+            }
+        }
+        return res;
+    }
+
+    public boolean isTemplateReference(Construct theConstruct,
+                                        Checker.CheckContext theContext,
+                                        String theTemplateName,
+                                        Catalog catalog) {
+        return catalog.hasTemplate(theContext.target(), theConstruct, theTemplateName);
+    }
+}
diff --git a/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/validation/TOSCAValidator.java b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/validation/TOSCAValidator.java
new file mode 100644
index 0000000..38bd84f
--- /dev/null
+++ b/dcaedt_validator/checker/src/main/java/org/onap/sdc/dcae/checker/validation/TOSCAValidator.java
@@ -0,0 +1,115 @@
+package org.onap.sdc.dcae.checker.validation;
+
+import kwalify.Rule;
+import kwalify.Types;
+import kwalify.Validator;
+import org.onap.sdc.common.onaplog.Enums.LogLevel;
+import org.onap.sdc.common.onaplog.OnapLoggerDebug;
+import org.onap.sdc.common.onaplog.OnapLoggerError;
+import org.onap.sdc.dcae.checker.IChecker;
+import org.onap.sdc.dcae.checker.Target;
+
+import java.util.*;
+
+public class TOSCAValidator extends Validator {
+    private static OnapLoggerError errLogger = OnapLoggerError.getInstance();
+    private static OnapLoggerDebug debugLogger = OnapLoggerDebug.getInstance();
+    private final IChecker checker;
+    //what were validating
+    private Target target;
+
+    /* Some of the TOSCA entries accept a 'short form/notation' instead of the canonical map representation.
+     * kwalify cannot easily express these alternatives and as such we handle them here. In the pre-validation phase we detect the presence of a short notation
+and compute the canonical form and validate it. In the post-validation phase we
+substitute the canonical form for the short form so that checking does not have to deal with it.
+     */
+
+    public Map<String, Object> getCanonicals() {
+        return canonicals;
+    }
+
+    private Map<String, Object> canonicals = new TreeMap<>();
+
+    public TOSCAValidator(Target theTarget, Object theSchema, IChecker checker) {
+        super(theSchema);
+        this.checker = checker;
+        this.target = theTarget;
+    }
+
+    public Target getTarget() {
+        return this.target;
+    }
+
+    /* hook method called by Validator#validate()
+     */
+    @Override
+    protected boolean preValidationHook(Object value, Rule rule, ValidationContext context) {
+
+        checker.validationHook("pre", value, rule, context);
+        //short form handling
+        String hint = rule.getShort();
+        if (value != null &&
+                hint != null) {
+
+            debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Attempting canonical at {}, rule {}", context.getPath(), rule.getName());
+
+            Object canonical = null;
+            //if the canonical form requires a collection
+            if (Types.isCollectionType(rule.getType())) {
+                //and the actual value isn't one
+                if (!(value instanceof Map || value instanceof List)) {
+                    //used to use singleton map/list here (was good for catching errors)
+                    //but there is the possibility if short forms within short forms so
+                    //the created canonicals need to accomodate other values.
+                    if (Types.isMapType(rule.getType())) {
+                        canonical = new HashMap();
+                        ((Map) canonical).put(hint, value);
+                    } else {
+                        //the hint is irrelevant here but we should impose a value when the target is a list
+                        canonical = new LinkedList();
+                        ((List) canonical).add(value);
+                    }
+                } else {
+                    //we can accomodate:
+                    // map to list of map transformation
+                    if (!Types.isMapType(rule.getType()) /* a seq */ &&
+                            value instanceof Map) {
+                        canonical = new LinkedList();
+                        ((List) canonical).add(value);
+                    } else {
+                        debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Grammar for rule {} (at {}) would require unsupported short form transformation: {} to {}", rule.getName(), context.getPath(), value.getClass(), rule.getType());
+                        return false;
+                    }
+                }
+
+                int errc = context.errorCount();
+                validateRule(canonical, rule, context);
+                if (errc != context.errorCount()) {
+                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Short notation for {} through {} at {} failed validation", rule.getName(), hint, context.getPath());
+                } else {
+                    debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Short notation for {} through {} at {} passed validation. Canonical form is {}", rule.getName(), hint, context.getPath(), canonical);
+                    //replace the short notation with the canonicall one so we don't
+                    //have to deal it again during checking
+                    this.canonicals.put(context.getPath(), canonical);
+                    return true;
+                }
+            } else {
+                debugLogger.log(LogLevel.DEBUG, this.getClass().getName(), "Grammar for rule {} (at {}) would require unsupported short form transformation: {} to {}", rule.getName(), context.getPath(), value.getClass(), rule.getType());
+            }
+        }
+
+        //perform default validation process
+        return false;
+    }
+
+    /*
+     * Only gets invoked once the value was succesfully verified against the syntax indicated by the given rule.
+     */
+    @Override
+    protected void postValidationHook(Object value,
+                                      Rule rule,
+                                      ValidationContext context) {
+        checker.validationHook("post", value, rule, context);
+    }
+
+}
\ No newline at end of file