Return ETag in response header

This update generates a unique hash for the payload and returns it
as an etag header.

Change-Id: I471dc1e74e8096d4fdb4f4db7f22e08ef4842ace
Issue-ID: AAI-1208
Signed-off-by: Michael Arrastia <MArrasti@amdocs.com>

4 files changed, 554 insertions, 22 deletions

diff --git a/champ-service/src/main/java/org/onap/champ/ChampRESTAPI.java b/champ-service/src/main/java/org/onap/champ/ChampRESTAPI.java
index 4b7c9a7..726944b 100644
--- a/champ-service/src/main/java/org/onap/champ/ChampRESTAPI.java
+++ b/champ-service/src/main/java/org/onap/champ/ChampRESTAPI.java
@@ -21,6 +21,7 @@
 package org.onap.champ;
 
 import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -40,6 +41,7 @@ import javax.ws.rs.PathParam;
 import javax.ws.rs.Produces;
 import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
+import javax.ws.rs.core.EntityTag;
 import javax.ws.rs.core.HttpHeaders;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
@@ -67,6 +69,7 @@ import org.onap.champ.service.logging.ChampMsgs;
 import org.onap.champ.service.logging.LoggingUtil;
 import org.onap.champ.util.ChampProperties;
 import org.onap.champ.util.ChampServiceConstants;
+import org.onap.champ.util.etag.EtagGenerator;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.module.SimpleModule;
@@ -77,6 +80,7 @@ public class ChampRESTAPI {
   private ObjectMapper mapper;
 
   private ChampDataService champDataService;
+  private EtagGenerator etagGenerator;
   private String TRANSACTION_METHOD = "method";
   private Timer timer;
 
@@ -85,8 +89,7 @@ public class ChampRESTAPI {
   private static Logger metricsLogger = LoggerFactory.getInstance().getMetricsLogger(ChampRESTAPI.class.getName());
   private static final Pattern QUERY_OBJECT_ID_URL_MATCH = Pattern.compile("_reserved_(.*)");
 
-
-  public ChampRESTAPI(ChampDataService champDataService, ChampAsyncRequestProcessor champAsyncRequestProcessor) {
+  public ChampRESTAPI(ChampDataService champDataService, ChampAsyncRequestProcessor champAsyncRequestProcessor) throws NoSuchAlgorithmException {
     this.champDataService = champDataService;
 
     // Async request handling is optional.
@@ -103,6 +106,8 @@ public class ChampRESTAPI {
     module.addSerializer(ChampRelationship.class, new ChampRelationshipSerializer());
     module.addDeserializer(ChampRelationship.class, new ChampRelationshipDeserializer());
     mapper.registerModule(module);
+
+    etagGenerator = new EtagGenerator();
   }
 
   @GET
@@ -134,13 +139,17 @@ public class ChampRESTAPI {
       if (retrieved == null) {
         response = Response.status(Status.NOT_FOUND).entity(objectId + " not found").build();
       } else {
-        response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).build();
+        EntityTag etag = new EntityTag(etagGenerator.computeHashForChampObject(retrieved));
+        response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).tag(etag).build();
       }
 
     } catch (JsonProcessingException e) {
       response = Response.status(Status.BAD_REQUEST).entity(e.getMessage()).build();
     } catch (ChampServiceException ce) {
       response = Response.status(ce.getHttpStatus()).entity(ce.getMessage()).build();
+    } catch (Exception e) {
+        response = Response.status(Status.INTERNAL_SERVER_ERROR).entity(e.getMessage()).build();
+        LoggingUtil.logInternalError(logger, e);
     } finally {
       logger.debug(response.getEntity().toString());
       LoggingUtil.logRestRequest(logger, auditLogger, req, response);
@@ -157,7 +166,6 @@ public class ChampRESTAPI {
     LoggingUtil.initMdcContext(req, headers);
     long startTimeInMs = System.currentTimeMillis();
     logger.info(ChampMsgs.INCOMING_REQUEST, tId, objectId);
-    ChampObject retrieved;
     Response response = null;
     try {
       ChampTransaction transaction = champDataService.getTransaction(tId);
@@ -200,7 +208,8 @@ public class ChampRESTAPI {
       ChampObject champObject = mapper.readValue(champObj, ChampObject.class);
 
       ChampObject created = champDataService.storeObject(champObject, Optional.ofNullable(transaction));
-      response = Response.status(Status.CREATED).entity(mapper.writeValueAsString(created)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampObject(created));
+      response = Response.status(Status.CREATED).entity(mapper.writeValueAsString(created)).tag(eTag).build();
     } catch (IOException e) {
       response = Response.status(Status.BAD_REQUEST).entity("Unable to parse the payload").build();
     } catch (ChampServiceException ce) {
@@ -239,8 +248,8 @@ public class ChampRESTAPI {
       ChampObject co = mapper.readValue(champObj, ChampObject.class);
       // check if key is present or if it equals the key that is in the URI
       ChampObject updated = champDataService.replaceObject(co, objectId, Optional.ofNullable(transaction));
-
-      response = Response.status(Status.OK).entity(mapper.writeValueAsString(updated)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampObject(updated));
+      response = Response.status(Status.OK).entity(mapper.writeValueAsString(updated)).tag(eTag).build();
     } catch (IOException e) {
       response = Response.status(Status.BAD_REQUEST).entity("Unable to parse the payload").build();
     } catch (ChampServiceException ce) {
@@ -265,13 +274,12 @@ public class ChampRESTAPI {
     LoggingUtil.initMdcContext(req, headers);
     long startTimeInMs = System.currentTimeMillis();
     List<ChampRelationship> retrieved;
-    Optional<ChampObject> rObject;
     Response response = null;
     ChampTransaction transaction = null;
     try {
-
       retrieved = champDataService.getRelationshipsByObject(oId, Optional.ofNullable(transaction));
-      response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampRelationships(retrieved));
+      response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).tag(eTag).build();
     } catch (JsonProcessingException e) {
       response = Response.status(Status.BAD_REQUEST).entity(e.getMessage()).build();
     } catch (ChampServiceException ce) {
@@ -294,7 +302,7 @@ public class ChampRESTAPI {
     LoggingUtil.initMdcContext(req, headers);
     long startTimeInMs = System.currentTimeMillis();
     String propertiesKey = ChampProperties.get(ChampServiceConstants.CHAMP_COLLECTION_PROPERTIES_KEY);
-    List<ChampObject> objects;
+    List<ChampObject> champObjects;
     Map<String, Object> filter = new HashMap<>();
 
     for (Map.Entry<String, List<String>> e : uriInfo.getQueryParameters().entrySet()) {
@@ -312,8 +320,9 @@ public class ChampRESTAPI {
 
     Response response = null;
     try {
-      objects = champDataService.queryObjects(filter, properties);
-      response = Response.status(Status.OK).type(MediaType.APPLICATION_JSON).entity(mapper.writeValueAsString(objects))
+      champObjects = champDataService.queryObjects(filter, properties);
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampObjects(champObjects));
+      response = Response.status(Status.OK).type(MediaType.APPLICATION_JSON).tag(eTag).entity(mapper.writeValueAsString(champObjects))
           .build();
     } catch (JsonProcessingException e) {
       e.printStackTrace();
@@ -351,7 +360,8 @@ public class ChampRESTAPI {
         response = Response.status(Status.NOT_FOUND).entity(rId + " not found").build();
         return response;
       }
-      response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampRelationship(retrieved));
+      response = Response.status(Status.OK).entity(mapper.writeValueAsString(retrieved)).tag(eTag).build();
 
     } catch (IOException e) {
       response = Response.status(Status.BAD_REQUEST).entity("Unable to parse the payload").build();
@@ -385,8 +395,8 @@ public class ChampRESTAPI {
       ChampRelationship r = mapper.readValue(relationship, ChampRelationship.class);
 
       ChampRelationship created = champDataService.storeRelationship(r, Optional.ofNullable(transaction));
-
-      response = Response.status(Status.CREATED).entity(mapper.writeValueAsString(created)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampRelationship(created));
+      response = Response.status(Status.CREATED).entity(mapper.writeValueAsString(created)).tag(eTag).build();
     } catch (IOException e) {
       response = Response.status(Status.BAD_REQUEST).entity("Unable to parse the payload").build();
     } catch (ChampServiceException ce) {
@@ -423,8 +433,8 @@ public class ChampRESTAPI {
       }
       ChampRelationship r = mapper.readValue(relationship, ChampRelationship.class);
       ChampRelationship updated = champDataService.updateRelationship(r, rId, Optional.ofNullable(transaction));
-
-      response = Response.status(Status.OK).entity(mapper.writeValueAsString(updated)).build();
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampRelationship(updated));
+      response = Response.status(Status.OK).entity(mapper.writeValueAsString(updated)).tag(eTag).build();
     } catch (IOException e) {
       response = Response.status(Status.BAD_REQUEST).entity("Unable to parse the payload").build();
     } catch (ChampServiceException ce) {
@@ -480,7 +490,7 @@ public class ChampRESTAPI {
       @Context HttpServletRequest req) {
     LoggingUtil.initMdcContext(req, headers);
     long startTimeInMs = System.currentTimeMillis();
-    List<ChampRelationship> list;
+    List<ChampRelationship> champRelationshipList;
     Map<String, Object> filter = new HashMap<>();
     for (Map.Entry<String, List<String>> e : uriInfo.getQueryParameters().entrySet()) {
       if (!reservedKeyMatcher ( QUERY_OBJECT_ID_URL_MATCH, e.getKey () )) {
@@ -489,8 +499,9 @@ public class ChampRESTAPI {
     }
     Response response = null;
     try {
-      list = champDataService.queryRelationships(filter);
-      response = Response.status(Status.OK).type(MediaType.APPLICATION_JSON).entity(mapper.writeValueAsString(list))
+      champRelationshipList = champDataService.queryRelationships(filter);
+      EntityTag eTag = new EntityTag(etagGenerator.computeHashForChampRelationships(champRelationshipList));
+      response = Response.status(Status.OK).type(MediaType.APPLICATION_JSON).tag(eTag).entity(mapper.writeValueAsString(champRelationshipList))
           .build();
     } catch (JsonProcessingException e) {
       e.printStackTrace();
@@ -595,7 +606,6 @@ public class ChampRESTAPI {
     }
     return response;
   }
-
   private boolean reservedKeyMatcher(Pattern p, String key) {
     Matcher m = p.matcher ( key );
     if (m.matches()) {
diff --git a/champ-service/src/main/java/org/onap/champ/util/HashGenerator.java b/champ-service/src/main/java/org/onap/champ/util/HashGenerator.java
new file mode 100644
index 0000000..d2d154b
--- /dev/null
+++ b/champ-service/src/main/java/org/onap/champ/util/HashGenerator.java
@@ -0,0 +1,63 @@
+/**
+ * ============LICENSE_START==========================================
+ * org.onap.aai
+ * ===================================================================
+ * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright © 2017-2018 Amdocs
+ * ===================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END============================================
+ */
+package org.onap.champ.util;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectOutput;
+import java.io.ObjectOutputStream;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+/**
+ * Generates a sha 256 hash
+ */
+public class HashGenerator {
+    private MessageDigest messageDigest;
+
+    public HashGenerator() throws NoSuchAlgorithmException {
+        this.messageDigest = MessageDigest.getInstance("SHA-256");
+    }
+
+    /**
+     * Generates a SHA 256 hash as a hexadecimal string for the inputs.
+     * Calls toString on the input objects to convert into a byte stream.
+     * @param values
+     * @return SHA 256 hash of the inputs as a hexadecimal string.
+     * @throws IOException
+     */
+    public String generateSHA256AsHex(Object... values) throws IOException {
+        byte[] bytes = convertToBytes(values);
+        byte[] digest = messageDigest.digest(bytes);
+        StringBuilder result = new StringBuilder();
+        for (byte byt : digest) result.append(Integer.toString((byt & 0xff) + 0x100, 16).substring(1));
+        return result.toString();
+    }
+
+    private byte[] convertToBytes(Object... values) throws IOException {
+        try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
+             ObjectOutput out = new ObjectOutputStream(bos)) {
+            for (Object object : values) {
+                out.writeObject(object.toString());
+            }
+            return bos.toByteArray();
+        }
+    }
+}
\ No newline at end of file
diff --git a/champ-service/src/main/java/org/onap/champ/util/etag/EtagGenerator.java b/champ-service/src/main/java/org/onap/champ/util/etag/EtagGenerator.java
new file mode 100644
index 0000000..ac5474e
--- /dev/null
+++ b/champ-service/src/main/java/org/onap/champ/util/etag/EtagGenerator.java
@@ -0,0 +1,107 @@
+/**
+ * ============LICENSE_START==========================================
+ * org.onap.aai
+ * ===================================================================
+ * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright © 2017-2018 Amdocs
+ * ===================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END============================================
+ */
+package org.onap.champ.util.etag;
+
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import org.onap.aai.champcore.model.ChampObject;
+import org.onap.aai.champcore.model.ChampRelationship;
+import org.onap.champ.util.HashGenerator;
+/**
+ * Computes etag for ChampObjects and ChampRelationships
+ *
+ */
+public class EtagGenerator {
+
+    private static final String AAI_LAST_MOD_TS = "aai-last-mod-ts";
+    private final HashGenerator hashGenerator;
+
+    public EtagGenerator() throws NoSuchAlgorithmException {
+        this.hashGenerator = new HashGenerator();
+    }
+
+     /**
+     * Takes in the ChampObject for which the hash is to be computed.
+     * @param champObject
+     * @return hash for the ChampObject
+     * @throws IOException
+     */
+    public String computeHashForChampObject(ChampObject champObject) throws IOException {
+        return hashGenerator.generateSHA256AsHex(champObject.getKey().orElse(""), champObject.getType(), filterAndSortProperties(champObject.getProperties()));
+    }
+
+    /**
+     * Takes in the ChampRelationship for which the hash is to be computed.
+     * @param ChampRelationship
+     * @return hash for the ChampRelationship
+     * @throws IOException
+     */
+    public String computeHashForChampRelationship(ChampRelationship champRelationship) throws IOException {
+        return hashGenerator.generateSHA256AsHex(champRelationship.getKey().orElse(""), champRelationship.getType(), filterAndSortProperties(champRelationship.getProperties()), computeHashForChampObject(champRelationship.getSource()), computeHashForChampObject(champRelationship.getTarget()));
+    }
+
+    /**
+     * Takes in the list of ChampObjects for which the hash is to be computed.<br>
+     * Computes the individual hash, adds them to a List. <br>
+     * Note that the order of items in the list affects the hash.
+     * @param champObjects
+     * @return hash for the list of ChampObjects
+     * @throws IOException
+     */
+    public String computeHashForChampObjects(List<ChampObject> champObjects) throws IOException {
+        List<String> champObjectHashList = new ArrayList<>();
+        for(ChampObject champObject : champObjects) {
+            champObjectHashList.add(computeHashForChampObject(champObject));
+        }
+        return hashGenerator.generateSHA256AsHex(champObjectHashList);
+    }
+
+    /**
+     * Takes in the list of ChampRelationships for which the hash is to be computed.<br>
+     * Computes the individual hash, adds them to a List. <br>
+     * Note that the order of items in the list affects the hash.
+     * @param champRelationships
+     * @return hash for the list of ChampRelationships
+     * @throws IOException
+     */
+    public String computeHashForChampRelationships(List<ChampRelationship> champRelationships) throws IOException {
+        List<String> champRelationshipHashList = new ArrayList<>();
+        for(ChampRelationship champRelationship : champRelationships) {
+            champRelationshipHashList.add(computeHashForChampRelationship(champRelationship));
+        }
+        return hashGenerator.generateSHA256AsHex(champRelationshipHashList);
+    }
+
+    private Map<String, Object> filterAndSortProperties(Map<String, Object> properties) {
+        return properties
+                .entrySet()
+                .stream()
+                .filter(x -> !x.getKey().equals(AAI_LAST_MOD_TS))
+                .sorted((x, y) -> x.getKey().compareTo(y.getKey()))
+                .collect(LinkedHashMap::new,
+                        (m, e) -> m.put(e.getKey(), e.getValue()),
+                        Map::putAll);
+    }
+}
diff --git a/champ-service/src/test/java/org/onap/champ/util/etag/TestEtagGenerator.java b/champ-service/src/test/java/org/onap/champ/util/etag/TestEtagGenerator.java
new file mode 100644
index 0000000..aaa8cb0
--- /dev/null
+++ b/champ-service/src/test/java/org/onap/champ/util/etag/TestEtagGenerator.java
@@ -0,0 +1,352 @@
+/**
+ * ============LICENSE_START==========================================
+ * org.onap.aai
+ * ===================================================================
+ * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright © 2017-2018 Amdocs
+ * ===================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END============================================
+ */
+package org.onap.champ.util.etag;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.not;
+import static org.junit.Assert.assertThat;
+import java.security.NoSuchAlgorithmException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.aai.champcore.model.ChampObject;
+import org.onap.aai.champcore.model.ChampRelationship;
+
+public class TestEtagGenerator {
+
+    private EtagGenerator etagGenerator;
+
+    @Before
+    public void init() throws NoSuchAlgorithmException {
+        etagGenerator = new EtagGenerator();
+    }
+
+    @Test
+    public void computeHashForIdenticalChampRelationshipObjects() throws Exception {
+        // everything is same
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship11), is(etagGenerator.computeHashForChampRelationship(champRelationship12)));
+    }
+
+    @Test
+    public void computeHashForIdenticalChampRelationshipObjects1() throws Exception {
+        // everything is same
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship11), is(etagGenerator.computeHashForChampRelationship(champRelationship12)));
+    }
+
+    @Test
+    public void computeHashForIdenticalChampRelationshipObjects2() throws Exception {
+        // everything is same
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship11), is(etagGenerator.computeHashForChampRelationship(champRelationship12)));
+    }
+
+
+    @Test
+    public void computeHashForChampRelationshipObjectsWithDifferentKey() throws Exception {
+        // key is different
+        ChampObject sourceChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship21 = new ChampRelationship.Builder(sourceChampObject21, targetChampObject21, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship22 = new ChampRelationship.Builder(sourceChampObject22, targetChampObject22, "tosca.relationships.HostedOn").key("rel1234").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship21), not(etagGenerator.computeHashForChampRelationship(champRelationship22)));
+    }
+
+    @Test
+    public void computeHashForChampRelationshipObjectsWithDifferentRelationShip() throws Exception {
+        // relationship is different
+        ChampObject sourceChampObject31 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject31 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship31 = new ChampRelationship.Builder(sourceChampObject31, targetChampObject31, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject32 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject32 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship32 = new ChampRelationship.Builder(sourceChampObject32, targetChampObject32, "tosca.relationships.RelatedTo").key("rel123").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship31), not(etagGenerator.computeHashForChampRelationship(champRelationship32)));
+    }
+
+    @Test
+    public void computeHashForChampRelationshipObjectsWithDifferentChampObjects() throws Exception {
+        // source/target different
+        ChampObject sourceChampObject41 = new ChampObject.Builder("pserver").key("a123456").property("prop1", "value1").build();
+        ChampObject targetChampObject41 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship41 = new ChampRelationship.Builder(sourceChampObject41, targetChampObject41, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject42 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject42 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship42 = new ChampRelationship.Builder(sourceChampObject42, targetChampObject42, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship41), not(etagGenerator.computeHashForChampRelationship(champRelationship42)));
+    }
+
+    @Test
+    public void computeHashForChampRelationshipObjectsWithDifferentProperties() throws Exception {
+        // property different
+        ChampObject sourceChampObject51 = new ChampObject.Builder("pserver").key("a123456").property("prop1", "value1").build();
+        ChampObject targetChampObject51 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship51 = new ChampRelationship.Builder(sourceChampObject51, targetChampObject51, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject52 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject52 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship52 = new ChampRelationship.Builder(sourceChampObject52, targetChampObject52, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampRelationship(champRelationship51), not(etagGenerator.computeHashForChampRelationship(champRelationship52)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalChampObjects() throws Exception {
+        ChampObject champObject1 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject2 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampObject(champObject1), is(etagGenerator.computeHashForChampObject(champObject2)));
+    }
+
+    @Test
+    public void testComputeHashForEquivalentChampObjects() throws Exception {
+        Map<String, Object> properties1 = new HashMap<>();
+        properties1.put("prop3", "value3");
+        properties1.put("prop1", "value1");
+        properties1.put("prop2", "value2");
+        properties1.put("aai-last-mod-ts", "1234");
+        // note aai-last-mod-ts value is different
+        Map<String, Object> properties2 = new HashMap<>();
+        properties2.put("prop3", "value3");
+        properties2.put("prop1", "value1");
+        properties2.put("prop2", "value2");
+        properties2.put("aai-last-mod-ts", "12345");
+
+
+        ChampObject champObject1 = new ChampObject.Builder("pserver").key("a1234").properties(properties1).build();
+        ChampObject champObject2 = new ChampObject.Builder("pserver").key("a1234").properties(properties2).build();
+        assertThat(etagGenerator.computeHashForChampObject(champObject1), is(etagGenerator.computeHashForChampObject(champObject2)));
+    }
+
+    @Test
+    public void testComputeHashForChampObjectsWithDifferentProperties() throws Exception {
+        ChampObject champObject3 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject champObject4= new ChampObject.Builder("pserver").key("a12345").property("prop2", "value1").build();
+        assertThat(etagGenerator.computeHashForChampObject(champObject3), not(etagGenerator.computeHashForChampObject(champObject4)));
+    }
+
+    @Test
+    public void testComputeHashForChampObjectsWithDifferentKey() throws Exception {
+        ChampObject champObject5 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject champObject6= new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        assertThat(etagGenerator.computeHashForChampObject(champObject5), not(etagGenerator.computeHashForChampObject(champObject6)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampObjects() throws Exception {
+        //List 1
+        ChampObject champObject11 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        List<ChampObject> champObjects1 = new ArrayList<>();
+        champObjects1.add(champObject11);
+        champObjects1.add(champObject12);
+        // List 2
+        ChampObject champObject21 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        List<ChampObject> champObjects2 = new ArrayList<>();
+        champObjects2.add(champObject21);
+        champObjects2.add(champObject22);
+
+        assertThat(etagGenerator.computeHashForChampObjects(champObjects1), is(etagGenerator.computeHashForChampObjects(champObjects2)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampObjectsWithDifferentOrder() throws Exception {
+        //List 1
+        ChampObject champObject11 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        List<ChampObject> champObjects1 = new ArrayList<>();
+        champObjects1.add(champObject11);
+        champObjects1.add(champObject12);
+        // List 2
+        ChampObject champObject21 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        List<ChampObject> champObjects2 = new ArrayList<>();
+        // Different order of the items added.
+        champObjects2.add(champObject22);
+        champObjects2.add(champObject21);
+
+        assertThat(etagGenerator.computeHashForChampObjects(champObjects1), not(etagGenerator.computeHashForChampObjects(champObjects2)));
+    }
+
+    @Test
+    public void testComputeHashForDifferentListOfChampObjects() throws Exception {
+        //List 1
+        ChampObject champObject11 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        List<ChampObject> champObjects1 = new ArrayList<>();
+        champObjects1.add(champObject11);
+        champObjects1.add(champObject12);
+        // List 2
+        ChampObject champObject21 = new ChampObject.Builder("pserver").key("a1234").property("prop1", "value1").build();
+        ChampObject champObject22 = new ChampObject.Builder("pserver").key("a123456").property("prop2", "value2").build();
+        List<ChampObject> champObjects2 = new ArrayList<>();
+        champObjects2.add(champObject21);
+        champObjects2.add(champObject22);
+
+        assertThat(etagGenerator.computeHashForChampObjects(champObjects1), not(etagGenerator.computeHashForChampObjects(champObjects2)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampRelationships() throws Exception {
+        //List 1
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships1 = new ArrayList<>();
+        champRelationships1.add(champRelationship11);
+        champRelationships1.add(champRelationship12);
+        // List 2
+        ChampObject sourceChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship21 = new ChampRelationship.Builder(sourceChampObject21, targetChampObject21, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship22 = new ChampRelationship.Builder(sourceChampObject22, targetChampObject22, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships2 = new ArrayList<>();
+        champRelationships2.add(champRelationship21);
+        champRelationships2.add(champRelationship22);
+
+        assertThat(etagGenerator.computeHashForChampRelationships(champRelationships1), is(etagGenerator.computeHashForChampRelationships(champRelationships2)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampRelationships1() throws Exception {
+        //List 1
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").build();
+        List<ChampRelationship> champRelationships1 = new ArrayList<>();
+        champRelationships1.add(champRelationship11);
+        champRelationships1.add(champRelationship12);
+        // List 2
+        ChampObject sourceChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship21 = new ChampRelationship.Builder(sourceChampObject21, targetChampObject21, "tosca.relationships.HostedOn").key("rel123").build();
+        ChampObject sourceChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship22 = new ChampRelationship.Builder(sourceChampObject22, targetChampObject22, "tosca.relationships.HostedOn").key("rel123").build();
+        List<ChampRelationship> champRelationships2 = new ArrayList<>();
+        champRelationships2.add(champRelationship21);
+        champRelationships2.add(champRelationship22);
+
+        assertThat(etagGenerator.computeHashForChampRelationships(champRelationships1), is(etagGenerator.computeHashForChampRelationships(champRelationships2)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampRelationships2() throws Exception {
+        //List 1
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships1 = new ArrayList<>();
+        champRelationships1.add(champRelationship11);
+        champRelationships1.add(champRelationship12);
+        // List 2
+        ChampObject sourceChampObject21 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject21 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship21 = new ChampRelationship.Builder(sourceChampObject21, targetChampObject21, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject22 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampObject targetChampObject22 = new ChampObject.Builder("pserver").key("a12345").build();
+        ChampRelationship champRelationship22 = new ChampRelationship.Builder(sourceChampObject22, targetChampObject22, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships2 = new ArrayList<>();
+        champRelationships2.add(champRelationship21);
+        champRelationships2.add(champRelationship22);
+
+        assertThat(etagGenerator.computeHashForChampRelationships(champRelationships1), is(etagGenerator.computeHashForChampRelationships(champRelationships2)));
+    }
+
+    @Test
+    public void testComputeHashForIdenticalListOfChampRelationshipsWithDifferentOrder() throws Exception {
+
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a123456").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a123456").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop2", "value2").build();
+        List<ChampRelationship> champRelationships1 = new ArrayList<>();
+        // List 1
+        champRelationships1.add(champRelationship11);
+        champRelationships1.add(champRelationship12);
+        // List 2, elements added in different order
+        List<ChampRelationship> champRelationships2 = new ArrayList<>();
+        champRelationships2.add(champRelationship12);
+        champRelationships2.add(champRelationship11);
+
+        assertThat(etagGenerator.computeHashForChampRelationships(champRelationships1), not(etagGenerator.computeHashForChampRelationships(champRelationships2)));
+    }
+
+    @Test
+    public void testComputeHashForDifferntListOfChampRelationships() throws Exception {
+      //List 1
+        ChampObject sourceChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject11 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship11 = new ChampRelationship.Builder(sourceChampObject11, targetChampObject11, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop1", "value1").build();
+        ChampObject targetChampObject12 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship12 = new ChampRelationship.Builder(sourceChampObject12, targetChampObject12, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships1 = new ArrayList<>();
+        champRelationships1.add(champRelationship11);
+        champRelationships1.add(champRelationship12);
+        // List 2
+        ChampObject sourceChampObject21 = new ChampObject.Builder("pserver").key("a123456").property("prop1", "value1").build();
+        ChampObject targetChampObject21 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship21 = new ChampRelationship.Builder(sourceChampObject21, targetChampObject21, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        ChampObject sourceChampObject22 = new ChampObject.Builder("pserver").key("a123456").property("prop1", "value1").build();
+        ChampObject targetChampObject22 = new ChampObject.Builder("pserver").key("a12345").property("prop2", "value2").build();
+        ChampRelationship champRelationship22 = new ChampRelationship.Builder(sourceChampObject22, targetChampObject22, "tosca.relationships.HostedOn").key("rel123").property("prop1", "value1").build();
+        List<ChampRelationship> champRelationships2 = new ArrayList<>();
+        champRelationships2.add(champRelationship21);
+        champRelationships2.add(champRelationship22);
+
+        assertThat(etagGenerator.computeHashForChampRelationships(champRelationships1), not(etagGenerator.computeHashForChampRelationships(champRelationships2)));
+    }
+
+
+}
+