Auto-resolve edge type

Auto-resolve edge type based on EdgeRules file.

Change-Id: Ic6de47f5172bc410efcdd5f08c1ea5c4f822610e
Issue-ID: AAI-1396
Signed-off-by: sblimkie <steven.blimkie@amdocs.com>

8 files changed, 178 insertions, 61 deletions

diff --git a/src/main/java/org/onap/crud/dao/GraphDao.java b/src/main/java/org/onap/crud/dao/GraphDao.java
index 6c1bca9..7cb3d4c 100644
--- a/src/main/java/org/onap/crud/dao/GraphDao.java
+++ b/src/main/java/org/onap/crud/dao/GraphDao.java
@@ -42,10 +42,12 @@ public interface GraphDao {
    *          - The unique identifier of the vertex to retrieve the edges for.
    * @param queryParams
    * 		  - query parameters to be passed
+   * @param txid
+   *      - a DB transaction ID to use (if null, no transactionId is used)
    * @return - A collection of edges.
    * @throws CrudException
    */
-  public List<Edge> getVertexEdges(String id, Map<String, String> queryParams) throws CrudException;
+  public List<Edge> getVertexEdges(String id, Map<String, String> queryParams, String txId) throws CrudException;
 
   /**
    * Retrieve a collection of {@link Vertex} objects which match the supplied
@@ -89,7 +91,7 @@ public interface GraphDao {
    * @throws CrudException
    */
   public OperationResult getEdge(String id, String type, Map<String, String> queryParams) throws CrudException;
-
+  
   /**
    * Retrieve a collection of {@link Edge} objects with a given type and which
    * match a set of supplied filter parameters.
@@ -172,7 +174,7 @@ public interface GraphDao {
    *          - The unique identifier of the edge to be deleted.
    * @throws CrudException
    */
-  public void deleteEdge(String id, String type) throws CrudException;
+  public void deleteEdge(String id) throws CrudException;
 
   public String openTransaction();
 
@@ -193,7 +195,9 @@ public interface GraphDao {
 
   public void deleteVertex(String id, String type, String txId) throws CrudException;
 
-  public void deleteEdge(String id, String type, String txId) throws CrudException;
+  public void deleteEdge(String id, String txId) throws CrudException;
 
-  public Edge getEdge(String id, String type, String txId) throws CrudException;
+  public Edge getEdge(String id, String txId) throws CrudException;
+  
+  public Edge getEdge(String id) throws CrudException;
 }
diff --git a/src/main/java/org/onap/crud/dao/champ/ChampDao.java b/src/main/java/org/onap/crud/dao/champ/ChampDao.java
index fd5de57..81980cc 100644
--- a/src/main/java/org/onap/crud/dao/champ/ChampDao.java
+++ b/src/main/java/org/onap/crud/dao/champ/ChampDao.java
@@ -141,26 +141,39 @@ public class ChampDao implements GraphDao {
   }
 
   @Override
-  public List<Edge> getVertexEdges(String id, Map<String, String> queryParams) throws CrudException {
-    StringBuilder strBuild = new StringBuilder(baseObjectUrl);
-    strBuild.append("/relationships/");
-    strBuild.append(id);
-    if(queryParams != null && !queryParams.isEmpty())
-    {
-        strBuild.append("?");
-        strBuild.append(URLEncodedUtils.format(convertToNameValuePair(queryParams), Charset.defaultCharset()));
-    }
+  public List<Edge> getVertexEdges(String id, Map<String, String> queryParams, String txId) throws CrudException {
+      StringBuilder strBuild = new StringBuilder(baseObjectUrl);
+      strBuild.append("/relationships/");
+      strBuild.append(id);
+
+      Map<String,String> queryParamsCopy = null;
+      if (queryParams != null) {
+          queryParamsCopy = new HashMap<String,String>(queryParams);
+      }
+      else {
+          queryParamsCopy = new HashMap<String,String>();
+      }
 
-    OperationResult getResult = client.get(strBuild.toString(), createHeader(), MediaType.APPLICATION_JSON_TYPE);
+      if (txId != null) {
+          queryParamsCopy.put("transactionId", txId);
+      }
 
-    if (getResult.getResultCode() == 200) {
-      return champGson.fromJson(getResult.getResult(), new TypeToken<List<Edge>>() {
-      }.getType());
-    } else {
-      // We didn't find a vertex with the supplied id, so just throw an
-      // exception.
-      throw createErrorException(getResult, javax.ws.rs.core.Response.Status.NOT_FOUND, "No vertex with id " + id + " found in graph");
-    }
+      if (!queryParamsCopy.isEmpty())
+      {
+          strBuild.append("?");
+          strBuild.append(URLEncodedUtils.format(convertToNameValuePair(queryParamsCopy), Charset.defaultCharset()));
+      }
+
+      OperationResult getResult = client.get(strBuild.toString(), createHeader(), MediaType.APPLICATION_JSON_TYPE);
+
+      if (getResult.getResultCode() == 200) {
+          return champGson.fromJson(getResult.getResult(), new TypeToken<List<Edge>>() {
+          }.getType());
+      } else {
+          // We didn't find a vertex with the supplied id, so just throw an
+          // exception.
+          throw createErrorException(getResult, javax.ws.rs.core.Response.Status.NOT_FOUND, "No vertex with id " + id + " found in graph");
+      }
   }
 
   @Override
@@ -343,7 +356,7 @@ public class ChampDao implements GraphDao {
   }
 
   @Override
-  public void deleteEdge(String id, String type) throws CrudException {
+  public void deleteEdge(String id) throws CrudException {
     String url = baseRelationshipUrl + "/" + id;
     OperationResult getResult = client.delete(url, createHeader(), MediaType.APPLICATION_JSON_TYPE);
 
@@ -512,7 +525,7 @@ public class ChampDao implements GraphDao {
   }
 
   @Override
-  public void deleteEdge(String id, String type, String txId) throws CrudException {
+  public void deleteEdge(String id, String txId) throws CrudException {
     String url = baseRelationshipUrl + "/" + id + "?transactionId=" + txId;
     OperationResult getResult = client.delete(url, createHeader(), MediaType.APPLICATION_JSON_TYPE);
 
@@ -524,19 +537,12 @@ public class ChampDao implements GraphDao {
   }
 
   @Override
-  public Edge getEdge(String id, String type, String txId) throws CrudException {
+  public Edge getEdge(String id, String txId) throws CrudException {
     String url = baseRelationshipUrl + "/" + id + "?transactionId=" + txId;
     OperationResult getResult = client.get(url, createHeader(), MediaType.APPLICATION_JSON_TYPE);
 
     if (getResult.getResultCode() == 200) {
       Edge edge = Edge.fromJson(getResult.getResult());
-
-      if (!edge.getType().equalsIgnoreCase(type)) {
-        // We didn't find an edge with the supplied type, so just throw an
-        // exception.
-        throw new CrudException("No edge with id " + id + " and type " + type + " found in graph",
-            javax.ws.rs.core.Response.Status.NOT_FOUND);
-      }
       return edge;
     } else {
       // We didn't find an edge with the supplied id, so just throw an
@@ -544,6 +550,20 @@ public class ChampDao implements GraphDao {
       throw createErrorException(getResult, javax.ws.rs.core.Response.Status.NOT_FOUND, "No edge with id " + id + " found in graph");
     }
   }
+  
+  @Override
+  public Edge getEdge(String id) throws CrudException {
+    String url = baseRelationshipUrl + "/" + id;
+    OperationResult getResult = client.get(url, createHeader(), MediaType.APPLICATION_JSON_TYPE);
+
+    if (getResult.getResultCode() == 200) {
+      Edge edge = Edge.fromJson(getResult.getResult());
+      return edge;
+    } else {
+      // We didn't find an edge with the supplied id, so just throw an exception.
+      throw createErrorException(getResult, javax.ws.rs.core.Response.Status.NOT_FOUND, "No edge with id " + id + " found in graph");
+    }
+  }
 
   public Vertex getVertex(String id, String type, String version, String txId) throws CrudException {
     String url = baseObjectUrl + "/" + id + "?transactionId=" + txId;
diff --git a/src/main/java/org/onap/crud/service/AbstractGraphDataService.java b/src/main/java/org/onap/crud/service/AbstractGraphDataService.java
index a5b52bd..59046ab 100644
--- a/src/main/java/org/onap/crud/service/AbstractGraphDataService.java
+++ b/src/main/java/org/onap/crud/service/AbstractGraphDataService.java
@@ -83,7 +83,7 @@ public abstract class AbstractGraphDataService {
     type = OxmModelValidator.resolveCollectionType(version, type);
     OperationResult vertexOpResult = daoForGet.getVertex(id, type, version, queryParams);
     Vertex vertex = Vertex.fromJson(vertexOpResult.getResult(), version);
-    List<Edge> edges = daoForGet.getVertexEdges(id, queryParams);
+    List<Edge> edges = daoForGet.getVertexEdges(id, queryParams, null);
     EntityTag entityTag = CrudServiceUtil.getETagFromHeader(vertexOpResult.getHeaders());
     return new ImmutablePair<>(entityTag, CrudResponseBuilder.buildGetVertexResponse(OxmModelValidator.validateOutgoingPayload(version, vertex), edges,
         version));
@@ -117,8 +117,7 @@ public abstract class AbstractGraphDataService {
         EdgePayload edgePayload = EdgePayload.fromJson(item.getValue().getAsJsonObject().toString());
 
         if (opr.getValue().getAsString().equalsIgnoreCase("delete")) {
-          RelationshipSchemaValidator.validateType(version, edgePayload.getType());
-          deleteBulkEdge(edgePayload.getId(), version, edgePayload.getType(), txId);
+          deleteBulkEdge(edgePayload.getId(), version, txId);
         }
       }
 
@@ -233,36 +232,68 @@ public abstract class AbstractGraphDataService {
                   .setTarget("services/inventory/" + version + "/" + target.getType() + "/" + target.getId().get());
             }
 
+            // If the type isn't set, resolve it based on on the sourece and target vertex types
+            if (edgePayload.getType() == null || edgePayload.getType().isEmpty()) {
+              edgePayload.setType(CrudServiceUtil.determineEdgeType(edgePayload, version));
+            }
+            
+            // TODO:  Champ needs to support getting an object's relationships within the context of an existing transaction.
+            //        Currently it doesn't.  Disabling multiplicity check until this happens.
+            
+            List<Edge> sourceVertexEdges = new ArrayList<Edge>();
+            List<Edge> targetVertexEdges = new ArrayList<Edge>();
+            
+            /*
             List<Edge> sourceVertexEdges =
                     EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(edgePayload.getSource()), edgePayload.getType(),
-                                 daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getSource()), null));
-
+                                 dao.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getSource()), null, txId));
+            
             List<Edge> targetVertexEdges =
                      EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(edgePayload.getTarget()), edgePayload.getType(),
-                                 daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getTarget()), null));
-
+                                 dao.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getTarget()), null, txId));
+            */
+            
             validatedEdge = RelationshipSchemaValidator.validateIncomingAddPayload(version, edgePayload.getType(), edgePayload, sourceVertexEdges,
                     targetVertexEdges);
             persistedEdge = addBulkEdge(validatedEdge, version, txId);
           } else if (opr.getValue().getAsString().equalsIgnoreCase("modify")) {
-            Edge edge = dao.getEdge(edgePayload.getId(), edgePayload.getType(), txId);
+            Edge edge = dao.getEdge(edgePayload.getId(), txId);
+            
+            // If the type isn't set, resolve it based on on the sourece and target vertex types
+            if (edgePayload.getType() == null || edgePayload.getType().isEmpty()) {
+              edgePayload.setType(edge.getType());
+            }
 
+            // TODO:  Champ needs to support getting an object's relationships within the context of an existing transaction.
+            //        Currently it doesn't.  Disabling multiplicity check until this happens.
+            
+            List<Edge> sourceVertexEdges = new ArrayList<Edge>();
+            List<Edge> targetVertexEdges = new ArrayList<Edge>();
+            
+            /*
             // load source and target vertex relationships for validation
             List<Edge> sourceVertexEdges =
                    EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(edgePayload.getSource()), edgePayload.getType(),
-                                daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getSource()), null));
+                                dao.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getSource()), null, txId));
 
             List<Edge> targetVertexEdges =
                     EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(edgePayload.getTarget()), edgePayload.getType(),
-                                daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getTarget()), null));
-
+                                dao.getVertexEdges(EdgePayloadUtil.getVertexNodeId(edgePayload.getTarget()), null, txId));
+            */
+            
             validatedEdge = RelationshipSchemaValidator.validateIncomingUpdatePayload(edge, version, edgePayload, edgePayload.getType(), sourceVertexEdges, targetVertexEdges);
             persistedEdge = updateBulkEdge(validatedEdge, version, txId);
           } else {
-            if ( (edgePayload.getId() == null) || (edgePayload.getType() == null) ) {
-              throw new CrudException("id and type must be specified for patch request", Status.BAD_REQUEST);
+            if (edgePayload.getId() == null) {
+              throw new CrudException("id must be specified for patch request", Status.BAD_REQUEST);
+            }
+            Edge existingEdge = dao.getEdge(edgePayload.getId(), txId);
+            
+            // If the type isn't set, resolve it based on on the sourece and target vertex types
+            if (edgePayload.getType() == null || edgePayload.getType().isEmpty()) {
+              edgePayload.setType(existingEdge.getType());
             }
-            Edge existingEdge = dao.getEdge(edgePayload.getId(), edgePayload.getType(), txId);
+            
             Edge patchedEdge = RelationshipSchemaValidator.validateIncomingPatchPayload(existingEdge, version, edgePayload);
             persistedEdge = updateBulkEdge(patchedEdge, version, txId);
           }
@@ -312,6 +343,6 @@ public abstract class AbstractGraphDataService {
 
   protected abstract Edge addBulkEdge(Edge edge, String version, String dbTransId) throws CrudException;
   protected abstract Edge updateBulkEdge(Edge edge, String version, String dbTransId) throws CrudException;
-  protected abstract void deleteBulkEdge(String id, String version, String type, String dbTransId) throws CrudException;
+  protected abstract void deleteBulkEdge(String id, String version, String dbTransId) throws CrudException;
 
 }
diff --git a/src/main/java/org/onap/crud/service/CrudAsyncGraphDataService.java b/src/main/java/org/onap/crud/service/CrudAsyncGraphDataService.java
index aa70a66..8d147eb 100644
--- a/src/main/java/org/onap/crud/service/CrudAsyncGraphDataService.java
+++ b/src/main/java/org/onap/crud/service/CrudAsyncGraphDataService.java
@@ -414,7 +414,18 @@ public class CrudAsyncGraphDataService extends AbstractGraphDataService {
     }
 
     @Override
-    protected void deleteBulkEdge(String id, String version, String type, String dbTransId) throws CrudException {
+    protected void deleteBulkEdge(String id, String version, String dbTransId) throws CrudException {
+        // Get the edge type
+        String type = null;
+        try {
+            Edge edge = daoForGet.getEdge(id);
+            type = edge.getType();
+        }
+        catch (CrudException ex) {
+            // Likely the client is trying to delete an edge which isn't present.  Just swallow the exception
+            // and let the bulk request fail via the normal path.
+        }
+        
         GraphEvent event = GraphEvent.builder(GraphEventOperation.DELETE)
                 .edge(new GraphEventEdge(id, version, type, null, null, null)).build();
         event.setDbTransactionId(dbTransId);
diff --git a/src/main/java/org/onap/crud/service/CrudGraphDataService.java b/src/main/java/org/onap/crud/service/CrudGraphDataService.java
index 9ff48c7..ae2d294 100644
--- a/src/main/java/org/onap/crud/service/CrudGraphDataService.java
+++ b/src/main/java/org/onap/crud/service/CrudGraphDataService.java
@@ -77,11 +77,11 @@ public class CrudGraphDataService extends AbstractGraphDataService {
     // load source and target vertex relationships for validation
     List<Edge> sourceVertexEdges =
              EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(payload.getSource()), type,
-                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getSource()), null));
+                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getSource()), null, null));
 
     List<Edge> targetVertexEdges =
               EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(payload.getTarget()), type,
-                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getTarget()), null));
+                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getTarget()), null, null));
 
     Edge edge = RelationshipSchemaValidator.validateIncomingAddPayload(version, type, payload, sourceVertexEdges, targetVertexEdges);
 
@@ -140,7 +140,7 @@ public class CrudGraphDataService extends AbstractGraphDataService {
   @Override
   public String deleteEdge(String version, String id, String type) throws CrudException {
     RelationshipSchemaValidator.validateType(version, type);
-    dao.deleteEdge(id, type);
+    dao.deleteEdge(id);
     return "";
   }
 
@@ -153,11 +153,11 @@ public class CrudGraphDataService extends AbstractGraphDataService {
     // load source and target vertex relationships for validation
     List<Edge> sourceVertexEdges =
              EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(payload.getSource()), type,
-                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getSource()), null));
+                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getSource()), null, null));
 
     List<Edge> targetVertexEdges =
               EdgePayloadUtil.filterEdgesByRelatedVertexAndType(EdgePayloadUtil.getVertexNodeType(payload.getTarget()), type,
-                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getTarget()), null));
+                          daoForGet.getVertexEdges(EdgePayloadUtil.getVertexNodeId(payload.getTarget()), null, null));
 
     Edge validatedEdge = RelationshipSchemaValidator.validateIncomingUpdatePayload(edge, version, payload, type, sourceVertexEdges, targetVertexEdges);
 
@@ -213,7 +213,7 @@ public class CrudGraphDataService extends AbstractGraphDataService {
   }
 
   @Override
-  protected void deleteBulkEdge(String id, String version, String type, String dbTransId) throws CrudException {
-    dao.deleteEdge(id, type, dbTransId);
+  protected void deleteBulkEdge(String id, String version, String dbTransId) throws CrudException {
+    dao.deleteEdge(id, dbTransId);
   }
 }
diff --git a/src/main/java/org/onap/crud/service/CrudRestService.java b/src/main/java/org/onap/crud/service/CrudRestService.java
index 25ab43a..3cfc657 100644
--- a/src/main/java/org/onap/crud/service/CrudRestService.java
+++ b/src/main/java/org/onap/crud/service/CrudRestService.java
@@ -504,10 +504,6 @@ public class CrudRestService {
 
       EdgePayload edgePayload = EdgePayload.fromJson(item.getValue().getAsJsonObject().toString());
 
-      if (edgePayload.getType() == null) {
-        throw new CrudException("Edge Type cannot be null for: " + item.getKey(), Status.BAD_REQUEST);
-      }
-
       if (!opr.getKey().equalsIgnoreCase("operation")) {
         throw new CrudException("operation missing in item: " + item.getKey(), Status.BAD_REQUEST);
       }
@@ -697,8 +693,9 @@ public class CrudRestService {
         }
 
         if (payload.getType() == null || payload.getType().isEmpty()) {
-          throw new CrudException("Missing Edge Type ", Status.BAD_REQUEST);
+          payload.setType(CrudServiceUtil.determineEdgeType(payload, version));
         }
+        
         ImmutablePair<EntityTag, String> result = graphDataService.addEdge(version, payload.getType(), payload);
         response = Response.status(Status.CREATED).entity(result.getValue()).tag(result.getKey()).type(mediaType).build();
       } else {
diff --git a/src/main/java/org/onap/crud/util/CrudServiceUtil.java b/src/main/java/org/onap/crud/util/CrudServiceUtil.java
index ed5fe53..5eeb38e 100644
--- a/src/main/java/org/onap/crud/util/CrudServiceUtil.java
+++ b/src/main/java/org/onap/crud/util/CrudServiceUtil.java
@@ -31,8 +31,12 @@ import javax.ws.rs.core.MultivaluedMap;
 import javax.ws.rs.core.Response.Status;
 import org.onap.aai.db.props.AAIProperties;
 import org.onap.crud.exception.CrudException;
+import org.onap.crud.parser.EdgePayload;
+import org.onap.crud.parser.util.EdgePayloadUtil;
 import org.onap.schema.EdgeRulesLoader;
 import org.onap.schema.OxmModelLoader;
+import org.onap.schema.RelationshipSchema;
+
 import com.google.gson.Gson;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonPrimitive;
@@ -138,4 +142,25 @@ public class CrudServiceUtil {
     return entityTag;
   }
 
+  public static String determineEdgeType(EdgePayload payload, String version) throws CrudException {
+    RelationshipSchema schema = EdgeRulesLoader.getSchemaForVersion(version);
+    
+    if (payload.getSource() == null || payload.getTarget() == null) {
+      throw new CrudException("Source/Target not specified", Status.BAD_REQUEST);
+    }
+    
+    Set<String> edgeTypes = schema.getValidRelationTypes(EdgePayloadUtil.getVertexNodeType(payload.getSource()), 
+        EdgePayloadUtil.getVertexNodeType(payload.getTarget()));
+    
+    if (edgeTypes.size() == 0) {
+      throw new CrudException("No valid relationship types from " + payload.getSource() + " to " + payload.getTarget(), Status.BAD_REQUEST);
+    }
+    
+    if (edgeTypes.size() > 1) {
+      throw new CrudException("Multiple possible relationship types from " + payload.getSource() + " to " + payload.getTarget(), Status.BAD_REQUEST);
+    }
+    
+    return edgeTypes.iterator().next();
+  }
+
 }
diff --git a/src/main/java/org/onap/schema/RelationshipSchema.java b/src/main/java/org/onap/schema/RelationshipSchema.java
index 2aab7a9..0cf419e 100644
--- a/src/main/java/org/onap/schema/RelationshipSchema.java
+++ b/src/main/java/org/onap/schema/RelationshipSchema.java
@@ -23,7 +23,9 @@ package org.onap.schema;
 
 import java.io.IOException;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import java.util.stream.Collectors;
 import javax.ws.rs.core.Response.Status;
 import org.codehaus.jackson.map.ObjectMapper;
@@ -47,6 +49,10 @@ public class RelationshipSchema {
   private Map<String, Map<String, Class<?>>> relationTypes  = new HashMap<>();
 
   private Map<String, EdgeRule> relationshipRules = new HashMap<>();
+  
+  // A map storing the list of valid edge types for a source/target pair
+  private Map<String, Set<String>> edgeTypesForNodePair = new HashMap<>();
+  
 
   @SuppressWarnings("unchecked")
   public RelationshipSchema(Multimap<String, EdgeRule> rules, String props) throws CrudException, IOException {
@@ -56,6 +62,16 @@ public class RelationshipSchema {
     for (EdgeRule rule : rules.values()) {
       String key = buildRelation(rule.getFrom(), rule.getTo(), rule.getLabel());
       relationshipRules.put(key, rule);
+      
+      String nodePairKey = buildNodePairKey(rule.getFrom(), rule.getTo());
+      if (edgeTypesForNodePair.get(nodePairKey) == null) {
+        Set<String> typeSet = new HashSet<String>();
+        typeSet.add(rule.getLabel());
+        edgeTypesForNodePair.put(nodePairKey, typeSet);
+      }
+      else {
+        edgeTypesForNodePair.get(nodePairKey).add(rule.getLabel());
+      }
     }
 
     Map<String, Class<?>> edgeProps = properties.entrySet().stream().collect(Collectors.toMap(p -> p.getKey(), p -> {
@@ -106,10 +122,23 @@ public class RelationshipSchema {
     return relationTypes.containsKey(type);
   }
 
+  public Set<String> getValidRelationTypes(String source, String target) {
+    Set<String> typeList = edgeTypesForNodePair.get(buildNodePairKey(source, target));
 
+    if (typeList == null) {
+      return new HashSet<String>();
+    }
+    
+    return typeList;
+  }
+  
   private String buildRelation(String source, String target, String relation) {
     return source + ":" + target + ":" + relation;
   }
+  
+  private String buildNodePairKey(String source, String target) {
+    return source + ":" + target;
+  }
 
   private Class<?> resolveClass(String type) throws CrudException, ClassNotFoundException {
     Class<?> clazz = Class.forName(type);