diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
index eacaf25..37bf0f2 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
@@ -61,6 +61,7 @@
 	public static final Type presenterType = new Type("SwingPresenter", "SwingPresenter");
 	private static String mainTypeName = null;
 	private static HashMap<String, HashMap<ResourceHierarchy, String>> componentNames = new HashMap<>();
+	protected Map<ResourceHierarchy, Map<ResourceHierarchy, Map<DataTransferChannel, String>>> updateMethods;
 	protected ILanguageSpecific langSpec = null;
 	protected IPlatformSpecific platformSpec = null;
 	
@@ -162,6 +163,7 @@
 	public ArrayList<CompilationUnit> generateCode(DataTransferModel model, DataFlowGraph flowGraph, IPlatformSpecific platformSpec, ILanguageSpecific langSpec) {
 		this.langSpec = langSpec;
 		this.platformSpec = platformSpec;
+		this.updateMethods = new HashMap<>();
 		ArrayList<CompilationUnit> codes = new ArrayList<>();
 		
 		Map<ResourceHierarchy, Set<ResourceHierarchy>> dependedRootComponentGraph = null;
@@ -512,6 +514,28 @@
 		}
 	}
 	
+	protected String getUpdateMethodName(ResourceHierarchy srcRes, ResourceHierarchy dstRes, DataTransferChannel ch) {
+		Map<ResourceHierarchy, Map<DataTransferChannel, String>> dstResUpdatesMethods = updateMethods.getOrDefault(dstRes, new HashMap<>());
+		updateMethods.put(dstRes, dstResUpdatesMethods);
+		Map<DataTransferChannel, String> dstResFromSrcResUpdatesMethods = dstResUpdatesMethods.getOrDefault(srcRes, new HashMap<>());
+		dstResUpdatesMethods.put(srcRes, dstResFromSrcResUpdatesMethods);
+		String updateMethodName = dstResFromSrcResUpdatesMethods.get(ch);
+		if (updateMethodName == null) {
+			String srcResComponentName = getComponentName(srcRes, langSpec);
+			String dstResComponentName = getComponentName(dstRes, langSpec);
+			if (generatesComponent(dstRes)) {
+				updateMethodName = updateMethodPrefix + from + srcResComponentName;
+			} else if (dstRes.getParent() != null) {
+				updateMethodName = updateMethodPrefix + dstResComponentName + from + srcResComponentName;
+			}
+			if (dstResFromSrcResUpdatesMethods.size() > 0) {
+				updateMethodName += dstResFromSrcResUpdatesMethods.size() + 1;		// To avoid declaring the method multiply.
+			}
+			dstResFromSrcResUpdatesMethods.put(ch, updateMethodName);
+		}
+		return updateMethodName;
+	}
+	
 	protected MethodDeclaration getConstructor(TypeDeclaration component) {
 		for (MethodDeclaration m: component.getMethods()) {
 			if (m.isConstructor()) return m;
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
index 69bcf51..4237555 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
@@ -62,12 +62,10 @@
 public class CodeGeneratorFromDataFlowGraph extends CodeGenerator {
 	protected Map<ResourceHierarchy, TypeDeclaration> resourceHierarchyToComponent;
 	protected Map<ResourceHierarchy, Map<String, VariableDeclaration>> constructorParams;
-	protected Map<ResourceHierarchy, Map<ResourceHierarchy, Map<DataTransferChannel, String>>> updateMethods;
 
 	public void generateCodeFromFlowGraph(DataTransferModel model, DataFlowGraph flowGraph, Collection<ResourceNode> components, ArrayList<CompilationUnit> codes, Map<ResourceHierarchy, Set<ResourceHierarchy>> dependedRootComponentGraph) {
 		resourceHierarchyToComponent = new HashMap<>();
 		constructorParams = new HashMap<>();
-		updateMethods = new HashMap<>();
 		Map<ResourceHierarchy, MethodDeclaration> resourceConstructors = new HashMap<>();
 		List<Map.Entry<ResourceHierarchy, String>> constructorStatements = new ArrayList<>();
 		Map<MethodDeclaration, Map.Entry<Expression, Map.Entry<ResourceHierarchy, ResourceHierarchy>>> updateStatements = new HashMap<>();
@@ -2913,6 +2911,24 @@
 		}
 		params.addAll(refParams);
 		
+		// Create a guard condition.
+		Term guardCondition = null;
+		for (Map.Entry<Expression, Expression> paramEnt: in.getResource().getPathParamsAndConstraints()) {
+			if (paramEnt.getValue() != null) {
+				Term newCondition = new Term(DataConstraintModel.eq);
+				newCondition.addChild(paramEnt.getKey(), true);
+				newCondition.addChild(paramEnt.getValue(), true);
+				if (guardCondition == null) {
+					guardCondition = newCondition;
+				} else {
+					Term composedCondition = new Term(DataConstraintModel.and);
+					composedCondition.addChild(guardCondition, true);
+					composedCondition.addChild(newCondition, true);
+					guardCondition = composedCondition;
+				}
+			}
+		}
+		
 		// Call the update method.
 		ResourceHierarchy dstRes = dstNode.getResourceHierarchy();
 		String updateMethodName = getUpdateMethodName(srcNode.getResourceHierarchy(), dstRes, ch);		// Get the method name.
@@ -2967,8 +2983,15 @@
 				if (!hasUpdateMethodinvoked) {
 					// The first call to an update method in this method
 					callerMethod.addStatement(restApiSpec.getHttpMethodParamsConstructionStatement(srcRes.getResourceName(), params, true));
-					callerMethod.addStatement(langSpec.getVariableDeclaration(DataConstraintModel.typeString.getInterfaceTypeName(), "result")
-												+ langSpec.getAssignment() + restApiSpec.getHttpMethodCallStatement(restApiSpec.getBaseURL(), dstPath, srcResName, httpMethod));
+					String httpMethodCall = langSpec.getVariableDeclaration(DataConstraintModel.typeString.getInterfaceTypeName(), "result")
+												+ langSpec.getAssignment() + restApiSpec.getHttpMethodCallStatement(restApiSpec.getBaseURL(), dstPath, srcResName, httpMethod);
+					if (guardCondition == null) {
+						// Non-conditional http method call.
+						callerMethod.addStatement(httpMethodCall);
+					} else {
+						// Conditional http method call by a guarded state transition.
+						callerMethod.addStatement(langSpec.getIfStatement(guardCondition, httpMethodCall));
+					}
 					if (srcComponent != null && !((RestApiSpecific) platformSpec).hasHttpClientFieldDeclaration(srcComponent)) {
 						// Declare a client field to connect to the destination resource of push transfer.
 						((RestApiSpecific) platformSpec).addHttpClientFieldDeclaration(srcComponent);
@@ -2983,7 +3006,14 @@
 				} else {
 					// After the second time of call to update methods in this method
 					callerMethod.addStatement(restApiSpec.getHttpMethodParamsConstructionStatement(srcRes.getResourceName(), params, false));
-					callerMethod.addStatement("result" + langSpec.getAssignment() + restApiSpec.getHttpMethodCallStatement(restApiSpec.getBaseURL(), dstPath, srcResName, httpMethod));
+					String httpMethodCall = "result" + langSpec.getAssignment() + restApiSpec.getHttpMethodCallStatement(restApiSpec.getBaseURL(), dstPath, srcResName, httpMethod);
+					if (guardCondition == null) {
+						// Non-conditional http method call.
+						callerMethod.addStatement(httpMethodCall);
+					} else {
+						// Conditional http method call by a guarded state transition.
+						callerMethod.addStatement(langSpec.getIfStatement(guardCondition, httpMethodCall));
+					}
 					if (srcComponent != null && !((RestApiSpecific) platformSpec).hasHttpClientFieldDeclaration(srcComponent)) {
 						// Declare a client field to connect to the destination resource of push transfer.
 						((RestApiSpecific) platformSpec).addHttpClientFieldDeclaration(srcComponent);
@@ -3004,8 +3034,16 @@
 				for (Map.Entry<Type, Map.Entry<String, String>> paramEnt: params) {
 					args.add(paramEnt.getValue().getValue());
 				}
-				callerMethod.addStatement(langSpec.getMethodInvocation(langSpec.getFieldAccessor(dstCompName), updateMethodName, args) 
-						+ langSpec.getStatementDelimiter());	// this.dst.updateDstFromSrc(value, refParams);
+				String methodInvocation = null;
+				methodInvocation = langSpec.getMethodInvocation(langSpec.getFieldAccessor(dstCompName), updateMethodName, args) 
+						+ langSpec.getStatementDelimiter();	// this.dst.updateDstFromSrc(value, refParams);
+				if (guardCondition == null) {
+					// Non-conditional invocation.
+					callerMethod.addStatement(methodInvocation);
+				} else {
+					// Conditional invocation by a guarded state transition.
+					callerMethod.addStatement(langSpec.getIfStatement(guardCondition, methodInvocation));
+				}
 			}
 		} else {
 			// Intra-service
@@ -3017,12 +3055,20 @@
 			for (Map.Entry<Type, Map.Entry<String, String>> paramEnt: params) {
 				args.add(paramEnt.getValue().getValue());
 			}
+			String methodInvocation = null;
 			if (srcRes != dstRes) {
-				callerMethod.addStatement(langSpec.getMethodInvocation(langSpec.getFieldAccessor(dstCompName), updateMethodName, args) 
-						+ langSpec.getStatementDelimiter());	// this.dst.updateDstFromSrc(value, refParams);
+				methodInvocation = langSpec.getMethodInvocation(langSpec.getFieldAccessor(dstCompName), updateMethodName, args) 
+						+ langSpec.getStatementDelimiter();	// this.dst.updateDstFromSrc(value, refParams);
 			} else {
-				callerMethod.addStatement(langSpec.getMethodInvocation(updateMethodName, args)
-						+ langSpec.getStatementDelimiter());	// this.updateDstFromSrc(value, refParams);
+				methodInvocation = langSpec.getMethodInvocation(updateMethodName, args)
+						+ langSpec.getStatementDelimiter();	// this.updateDstFromSrc(value, refParams);
+			}
+			if (guardCondition == null) {
+				// Non-conditional invocation.
+				callerMethod.addStatement(methodInvocation);
+			} else {
+				// Conditional invocation by a guarded state transition.
+				callerMethod.addStatement(langSpec.getIfStatement(guardCondition, methodInvocation));
 			}
 		}
 		if (addForStatement) {
@@ -3117,28 +3163,6 @@
 		}
 		return update;
 	}
-	
-	protected String getUpdateMethodName(ResourceHierarchy srcRes, ResourceHierarchy dstRes, DataTransferChannel ch) {
-		Map<ResourceHierarchy, Map<DataTransferChannel, String>> dstResUpdatesMethods = updateMethods.getOrDefault(dstRes, new HashMap<>());
-		updateMethods.put(dstRes, dstResUpdatesMethods);
-		Map<DataTransferChannel, String> dstResFromSrcResUpdatesMethods = dstResUpdatesMethods.getOrDefault(srcRes, new HashMap<>());
-		dstResUpdatesMethods.put(srcRes, dstResFromSrcResUpdatesMethods);
-		String updateMethodName = dstResFromSrcResUpdatesMethods.get(ch);
-		if (updateMethodName == null) {
-			String srcResComponentName = getComponentName(srcRes, langSpec);
-			String dstResComponentName = getComponentName(dstRes, langSpec);
-			if (generatesComponent(dstRes)) {
-				updateMethodName = updateMethodPrefix + from + srcResComponentName;
-			} else if (dstRes.getParent() != null) {
-				updateMethodName = updateMethodPrefix + dstResComponentName + from + srcResComponentName;
-			}
-			if (dstResFromSrcResUpdatesMethods.size() > 0) {
-				updateMethodName += dstResFromSrcResUpdatesMethods.size() + 1;		// To avoid declaring the method multiply.
-			}
-			dstResFromSrcResUpdatesMethods.put(ch, updateMethodName);
-		}
-		return updateMethodName;
-	}
 
 	protected void declareGetterAccessorInTheRootResource(ResourceNode resourceNode, TypeDeclaration rootComponent) {
 		if (resourceNode.getResourceHierarchy().getParent() != null) {