diff --git a/AlgebraicDataflowArchitectureModel/models/OnlineBattleGame.model b/AlgebraicDataflowArchitectureModel/models/OnlineBattleGame.model
new file mode 100644
index 0000000..ceb7100
--- /dev/null
+++ b/AlgebraicDataflowArchitectureModel/models/OnlineBattleGame.model
@@ -0,0 +1,31 @@
+channel CIO_Signup{
+		out accounts(adb:Map, signUp(aid:Str, name:Str)) == insert(adb, aid, {"name": name})
+}
+
+channel CIO_ChangeName(aid:Str) {
+	out accounts.{aid}.name(prev_name:Str, changeName(name)) == name
+}
+
+channel CIO_CreateRoom {
+	out rooms(rdb:Map, createRoom(rid:Str, blue_id:Str, red_id:Str)) == insert(rdb, rid, {"blue_id": blue_id, "red_id": red_id})
+}
+
+channel CIO_ChangeRed_id(rid:Str) {
+	out rooms.{rid}.red_id(prev_red_id:Str, changeRed_id(red_id)) == red_id
+}
+
+channel CIO_ChangeBlue_id(rid:Str) {
+	out rooms.{rid}.blue_id(prev_blue_id:Str, changeBlue_id(blue_id)) == blue_id
+}
+
+channel C_red(rid:Str) {
+    in rooms.{rid}.red_id(prev_aid:Str, sync(aid, name)) == aid 
+    in accounts.{aid}.name(prev_name:Str, sync(aid, name)) == name
+    out rooms.{rid}.red_name(prev_name:Str, sync(aid, name)) == name
+}
+
+channel C_blue(rid:Str) {
+    in rooms.{rid}.blue_id(prev_aid:Str, sync(aid, name)) == aid
+    in accounts.{aid}.name(prev_name:Str, sync(aid, name)) == name
+    out rooms.{rid}.blue_name(prev_name:Str, sync(aid, name)) == name
+}
\ No newline at end of file
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java b/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
index 21220f2..2969692 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
@@ -1949,38 +1949,40 @@
 			if (idx == 3) {
 				// exp is a json argument (0:t = addMember(3:json, 1:key, 2:value)).
 				Type jsonType = json.get(System.identityHashCode(jsonMemberGroup));
-				Map<String, Type> memberTypes = new HashMap<>(jsonMemberTypes.get(jsonType));
-				Map<String, Type> argMemberTypes = new HashMap<>(memberTypes);
-				String keyName = null;
-				Type valueType = null;
-				if (jsonMemberGroup.get(1) instanceof Constant) {
-					keyName = ((Constant) jsonMemberGroup.get(1)).getSymbol().getName();
-					valueType = ((Constant) jsonMemberGroup.get(1)).getType();
-					argMemberTypes.remove(keyName);
-				}
-				Type jsonArgType = jsonTypes.get(argMemberTypes);
-				Type newJsonArgType = getExpTypeIfUpdatable(jsonArgType, exp);
-				if (newJsonArgType != null && keyName != null) {
-					// Propagate an update of a json arg's type to its container's (json's) type.
-					argMemberTypes = ((JsonType) newJsonArgType).getMemberTypes();
-					argMemberTypes.put(keyName, valueType);
-					memberTypes.putAll(argMemberTypes);
-					Type newJsonType = jsonTypes.get(memberTypes);
-					if (newJsonType == null) {
-						// Create new json type.
-						newJsonType = createNewJsonType(memberTypes, jsonType);
+				if (jsonType != null && jsonMemberTypes.get(jsonType) != null) {
+					Map<String, Type> memberTypes = new HashMap<>(jsonMemberTypes.get(jsonType));
+					Map<String, Type> argMemberTypes = new HashMap<>(memberTypes);
+					String keyName = null;
+					Type valueType = null;
+					if (jsonMemberGroup.get(1) instanceof Constant) {
+						keyName = ((Constant) jsonMemberGroup.get(1)).getSymbol().getName();
+						valueType = ((Constant) jsonMemberGroup.get(1)).getType();
+						argMemberTypes.remove(keyName);
 					}
-					// Update the type of the json term and record the updated expression.
-					Map<Integer, Expression> updateExps = getUpdateSet(updateFromJson, jsonMemberGroup);
-					Expression jsonExp = jsonMemberGroup.get(0);
-					if (jsonExp instanceof Variable) {
-						((Variable) jsonExp).setType(newJsonType);
-						updateExps.put(System.identityHashCode(jsonExp), jsonExp);
-					} else if (jsonExp instanceof Term) {
-						((Term) jsonExp).setType(newJsonType);
-						updateExps.put(System.identityHashCode(jsonExp), jsonExp);
+					Type jsonArgType = jsonTypes.get(argMemberTypes);
+					Type newJsonArgType = getExpTypeIfUpdatable(jsonArgType, exp);
+					if (newJsonArgType != null && keyName != null) {
+						// Propagate an update of a json arg's type to its container's (json's) type.
+						argMemberTypes = ((JsonType) newJsonArgType).getMemberTypes();
+						argMemberTypes.put(keyName, valueType);
+						memberTypes.putAll(argMemberTypes);
+						Type newJsonType = jsonTypes.get(memberTypes);
+						if (newJsonType == null) {
+							// Create new json type.
+							newJsonType = createNewJsonType(memberTypes, jsonType);
+						}
+						// Update the type of the json term and record the updated expression.
+						Map<Integer, Expression> updateExps = getUpdateSet(updateFromJson, jsonMemberGroup);
+						Expression jsonExp = jsonMemberGroup.get(0);
+						if (jsonExp instanceof Variable) {
+							((Variable) jsonExp).setType(newJsonType);
+							updateExps.put(System.identityHashCode(jsonExp), jsonExp);
+						} else if (jsonExp instanceof Term) {
+							((Term) jsonExp).setType(newJsonType);
+							updateExps.put(System.identityHashCode(jsonExp), jsonExp);
+						}
+						json.put(System.identityHashCode(jsonMemberGroup), newJsonType);
 					}
-					json.put(System.identityHashCode(jsonMemberGroup), newJsonType);
 				}
 			} else if (idx == 2) {
 				// exp is a value (0:t = addMember(3:json, 1:key, 2:value) or 2:value = dot(0:list/map, 1:key)).
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
index 9aa4b39..89f87e9 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
@@ -633,7 +633,27 @@
 		
 		// Add leaf reference fields to the parent components.
 		for (Map.Entry<ResourceHierarchy, FieldDeclaration> entry: fields) {
-			resourceComponents.get(entry.getKey()).addField(entry.getValue());
+			ResourceHierarchy resource = entry.getKey();
+			FieldDeclaration field = entry.getValue();
+			TypeDeclaration component = resourceComponents.get(resource);
+			boolean existsField = false;
+			for (FieldDeclaration fld: component.getFields()) {
+				if (fld.getName().equals(field.getName())) {
+					existsField = true;
+					break;
+				}
+			}
+			if (!existsField) {
+				component.addField(field);
+				if (field.getType().equals(typeClient)) {
+					for (CompilationUnit cu: codes) {
+						if (cu.types().contains(component)) {
+							cu.addImport(new ImportDeclaration("javax.ws.rs.client.*"));
+							break;
+						}
+					}
+				}
+			}
 		}
 		
 		// Add constructor parameters to the ancestor components.