diff --git a/AlgebraicDataflowArchitectureModel/models/Citrus.model b/AlgebraicDataflowArchitectureModel/models/Citrus.model
index 3730a7d..700e4dd 100644
--- a/AlgebraicDataflowArchitectureModel/models/Citrus.model
+++ b/AlgebraicDataflowArchitectureModel/models/Citrus.model
@@ -3,7 +3,7 @@
 }
 
 channel CreateBook(aid:Str) {
-    out accounts.{aid}.books(bookList:List, createBook(title:Str)) = append(bookList, {"title": title, "todos":nil, "favorited": nil})
+    out accounts.{aid}.books(bookList:List, createBook(title:Str)) = append(bookList, {"title": title, "todos": nil, "favorited": nil})
 }
 
 channel DeleteAccount {
@@ -11,7 +11,7 @@
 }
 
 channel ChangeAccountName {
-    out accounts(accDB:Map, changeAccountId(aid:Str, newAid:Str)) = insert(delete(accDB, aid), newAid, lookup(accDB, aid))
+    out accounts(accDB:Map, changeAccountId(aid:Str, newAid:Str)) = if(aid == newAid, accDB, delete(insert(accDB, newAid, lookup(accDB, aid)), aid))
 }
 
 channel ChangeBookName(aid:Str, bid:Int) {
@@ -23,7 +23,7 @@
 }
 
 channel CreateToDo(aid:Str, bid:Int) {
-    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, createtodo(title:Str, year:Str, month:Str, day:Str)) = insert(toDoDB, year, 
+    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, createtodo(year:Str, month:Str, day:Str, title:Str)) = insert(toDoDB, year, 
                                                                                                         	insert(lookup(toDoDB, year), month, 
                                                                                                         	insert(lookup(lookup(toDoDB, year), month), day, 
                                                                                                         	append(lookup(lookup(lookup(toDoDB, year), month), day), {"title": title, "check": false}))))
@@ -37,8 +37,15 @@
 	out accounts.{aid}.books.{bid}.todos.{year}.{month}.{day}.{tid}.check(check:Bool, changeCheck(newCheck)) = newCheck
 }
 
-channel DeleteToDo(aid:Str, bid:Int, year:Str, month:Str, day:Str, tid:Int) {
-    out accounts.{aid}.books.{bid}.todos.{year}.{month}.{day}(todoList:List, deleteToDo(tid:int)) = if(tid < length(todoList), remove(todoList, tid), todoList)
+channel DeleteToDo(aid:Str, bid:Int) {
+    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, deleteToDo(year:Str, month:Str, day:Str, tid:int)) = insert(toDoDB, 
+    																											year,
+                                                                                                        		insert(lookup(toDoDB, year), 
+                                                                                                        				month, 
+                                                                                                        				insert(lookup(lookup(toDoDB, year), month), 
+                                                                                                        						day, 
+                                                                                                        						remove(lookup(lookup(lookup(toDoDB, year), month), day),
+                                                                                                        								tid))))
 }
 
 channel AddFavorited(aid:Str, bid:Int) {
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
index fe86c0c..7792b4f 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
@@ -98,14 +98,14 @@
 					if (generatesComponent(child)) {
 						return langSpec.newListType(getComponentName(child, langSpec));
 					} else {
-						return langSpec.newListType(getImplStateType(child, langSpec).getImplementationTypeName());
+						return langSpec.newListType(getImplStateType(child, langSpec).getInterfaceTypeName());
 					}
 				} else if (DataConstraintModel.typeMap.isAncestorOf(res.getResourceStateType())) {
 					// map.
 					if (generatesComponent(child)) {
 						return langSpec.newMapType(DataConstraintModel.typeString, getComponentName(child, langSpec));
 					} else {
-						return langSpec.newMapType(DataConstraintModel.typeString, getImplStateType(child, langSpec).getImplementationTypeName());
+						return langSpec.newMapType(DataConstraintModel.typeString, getImplStateType(child, langSpec).getInterfaceTypeName());
 					}
 				}
 				return null;
@@ -117,9 +117,11 @@
 	}
 	
 	public static boolean generatesComponent(ResourceHierarchy res) {
-		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
-//		Type resType = res.getResourceStateType();
-//		return DataConstraintModel.typeJson.isAncestorOf(resType) || DataConstraintModel.typeList.isAncestorOf(resType) || DataConstraintModel.typeMap.isAncestorOf(resType);
+		if (res.getParent() == null) return true;
+		if (res.getChildren() == null || res.getChildren().size() == 0) return false;
+		if (res.getNumParameters() > 0 && res.getChildren().size() == 1 && res.getChildren().iterator().next().getNumParameters() > 0) return false;
+		return true;
+//		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
 	}
 
 	/**
@@ -367,29 +369,37 @@
 		}
 	}
 
-	protected void fillChildGetterMethod(MethodDeclaration childGetter, ResourceHierarchy child, Type parentResourceType, ILanguageSpecific langSpec) {
-		if (DataConstraintModel.typeList.isAncestorOf(parentResourceType)) {
-			Term selector = new Term(DataConstraintModel.get);
-			selector.addChild(new Variable(langSpec.getFieldAccessor(fieldOfResourceState)));
-			selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-			selector.setType(childGetter.getReturnType());
-			String[] sideEffects = new String[] {null};
-			String returnValue = selector.toImplementation(sideEffects);
-			if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-			childGetter.addStatement(langSpec.getReturnStatement(returnValue) + langSpec.getStatementDelimiter());
-		} else if (DataConstraintModel.typeMap.isAncestorOf(parentResourceType)) {
-			Term selector = new Term(DataConstraintModel.lookup);
-			selector.addChild(new Variable(langSpec.getFieldAccessor(fieldOfResourceState)));
-			selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-			selector.setType(childGetter.getReturnType());
-			String[] sideEffects = new String[] {null};
-			String returnValue = selector.toImplementation(sideEffects);
-			if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-			childGetter.addStatement(langSpec.getReturnStatement(returnValue) + langSpec.getStatementDelimiter());
+	protected void fillDescendantGetterMethod(MethodDeclaration descendantGetter, ResourceHierarchy descendant, ResourceHierarchy ancestor, TypeDeclaration ancestorComponent, ILanguageSpecific langSpec) {
+		Expression selector;
+		if (DataConstraintModel.typeList.isAncestorOf(ancestor.getResourceStateType())) {
+			selector = new Variable(langSpec.getFieldAccessor(fieldOfResourceState));
+		} else if (DataConstraintModel.typeMap.isAncestorOf(ancestor.getResourceStateType())) {
+			selector = new Variable(langSpec.getFieldAccessor(fieldOfResourceState));
 		} else {
-			String fieldName = langSpec.toVariableName(getComponentName(child, langSpec));
-			childGetter.addStatement(langSpec.getReturnStatement(langSpec.getFieldAccessor(fieldName)) + langSpec.getStatementDelimiter());
-		}		
+			String fieldName = langSpec.toVariableName(getComponentName(descendant, langSpec));
+			selector = new Variable(langSpec.getFieldAccessor(fieldName));
+		}
+		if (descendantGetter.getParameters() != null) {
+			for (VariableDeclaration param: descendantGetter.getParameters()) {
+				if (DataConstraintModel.typeInt.isAncestorOf(param.getType())) {
+					Term newSelector = new Term(DataConstraintModel.get);
+					newSelector.addChild(selector);
+					newSelector.addChild(new Variable(param.getName()));
+					selector = newSelector;
+				} else if (DataConstraintModel.typeString.isAncestorOf(param.getType())) {
+					Term newSelector = new Term(DataConstraintModel.lookup);
+					newSelector.addChild(selector);
+					newSelector.addChild(new Variable(param.getName()));
+					selector = newSelector;
+				}
+			}
+		}
+		if (descendantGetter != null && (descendantGetter.getBody() == null || descendantGetter.getBody().getStatements().size() == 0)) {
+			String[] sideEffects = new String[] {null};
+			String returnValue = selector.toImplementation(sideEffects);
+			if (sideEffects[0] != null) descendantGetter.addStatement(sideEffects[0]);
+			descendantGetter.addStatement(langSpec.getReturnStatement(returnValue) + langSpec.getStatementDelimiter());
+		}
 	}
 
 	protected void declareAccessorInMainComponent(TypeDeclaration mainComponent, ResourceNode accessRes, MethodDeclaration stateGetter, ILanguageSpecific langSpec) {
@@ -453,6 +463,16 @@
 		return null;
 	}
 	
+	protected static List<MethodDeclaration> getGetterMethods(TypeDeclaration component, String resourceName) {
+		List<MethodDeclaration> getters = new ArrayList<>();
+		for (MethodDeclaration m: component.getMethods()) {
+			if (m.getName().startsWith(getterPrefix + resourceName)) {
+				getters.add(m);
+			}
+		}
+		return getters;
+	}
+	
 	protected MethodDeclaration getUpdateMethod(Edge inEdge, TypeDeclaration component,
 			Map<Edge, Map<PushPullValue, List<ResourceNode>>> dataFlowInform, ILanguageSpecific langSpec) {
 		List<ResourceNode> passedResoueces = dataFlowInform.get(inEdge).get(PushPullValue.PUSH);
@@ -602,6 +622,7 @@
 					// iterate from the root resource
 					Term getter = null;
 					int v = 1;
+					int arity = 2;
 					while (!pathStack.empty()) {
 						curPath = pathStack.pop();
 						String typeName = getComponentName(curPath.getResourceHierarchy(), langSpec);
@@ -610,23 +631,65 @@
 							String fieldName = langSpec.toVariableName(typeName);
 							getter = new Field(fieldName, new Type(typeName, typeName));
 						} else {
-							Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
-							newGetter.addChild(getter);
-							if (curPath.getResourceHierarchy().getNumParameters() > 0) {
-								Variable var = null;
-								Expression param = curPath.getLastParam();
-								if (param instanceof Variable) {
-									var = (Variable) param;
-								} else if (param instanceof Term) {
-									var = new Variable("v" + v, ((Term) param).getType());
+							if (generatesComponent(curPath.getResourceHierarchy())) {
+								if (arity == 2) {
+									Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
+									newGetter.addChild(getter);
+									if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+										Variable var = null;
+										Expression param = curPath.getLastParam();
+										if (param instanceof Variable) {
+											var = (Variable) param;
+										} else if (param instanceof Term) {
+											var = new Variable("v" + v, ((Term) param).getType());
+										}
+										if (var != null) {
+											newGetter.addChild(var);
+											newGetter.getSymbol().setArity(2);
+										}
+										v++;
+									}
+									getter = newGetter;
+								} else {
+									if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+										Variable var = null;
+										Expression param = curPath.getLastParam();
+										if (param instanceof Variable) {
+											var = (Variable) param;
+										} else if (param instanceof Term) {
+											var = new Variable("v" + v, ((Term) param).getType());
+										}
+										if (var != null) {
+											getter.getSymbol().setArity(arity);
+											getter.addChild(var);
+										}
+										v++;
+									}
 								}
-								if (var != null) {
-									newGetter.addChild(var);
-									newGetter.getSymbol().setArity(2);
+								arity = 2;
+							} else {
+								// to get a descendant resource directly.
+								if (arity == 2) {
+									Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
+									newGetter.addChild(getter);
+									getter = newGetter;
 								}
-								v++;
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									Variable var = null;
+									Expression param = curPath.getLastParam();
+									if (param instanceof Variable) {
+										var = (Variable) param;
+									} else if (param instanceof Term) {
+										var = new Variable("v" + v, ((Term) param).getType());
+									}
+									if (var != null) {
+										getter.getSymbol().setArity(arity);
+										getter.addChild(var);
+										arity++;
+									}
+									v++;
+								}
 							}
-							getter = newGetter;
 						}
 					}
 					
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
index 00cc669..beba922 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
@@ -9,6 +9,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.Stack;
 import java.util.AbstractMap.SimpleEntry;
 
 import code.ast.Block;
@@ -59,7 +60,7 @@
 		List<Map.Entry<ResourceHierarchy, VariableDeclaration>> constructorParams = new ArrayList<>();
 		List<Map.Entry<ResourceHierarchy, String>> constructorStatements = new ArrayList<>();
 		Map<MethodDeclaration, Map.Entry<Expression, ResourceHierarchy>> updateStatements = new HashMap<>();
-		Map<ResourceHierarchy, Set<ResourceHierarchy>> childGetters = new HashMap<>();
+		Map<ResourceHierarchy, Set<ResourceHierarchy>> descendantGetters = new HashMap<>();
 		
 		// For each components (1st pass).
 		for (Node componentNode: components) {
@@ -108,8 +109,8 @@
 					declareAccessorInMainComponent(mainComponent, resourceNode, stateGetter, langSpec);
 				}
 				if (component != null) {
-					// Declare the getter methods in this resource to obtain the children resources.
-					declareChildGetterMethod(resourceNode, component, childGetters, langSpec);
+					// Declare the getter methods in this resource to obtain the descendant resources.
+					declareDescendantGetterMethods(resourceNode, component, descendantGetters, langSpec);
 				}
 			}
 		}
@@ -143,9 +144,9 @@
 			// Declare the fields to refer to other resources in the parent/this component, and the state field in the parent component.
 			declareFieldsToReferToOtherResourcesAndStateFieldInParentComponent(resourceNode, component, parentComponent, constructorParams, langSpec);
 			
-			// Declare the getter method in this resource to obtain the state.
+			// Declare the getter method to obtain the resource state in an ancestor resource.
 			if (component == null) {
-				MethodDeclaration stateGetter = declareStateGetterMethodInParent(resourceNode, parentComponent, resStateType, langSpec);
+				MethodDeclaration stateGetter = declareStateGetterMethodInAncestor(resourceNode, resourceComponents, resStateType, langSpec);
 				
 				if (stateGetter != null) {
 					// Declare the accessor method in the main component to call the getter method.
@@ -267,7 +268,7 @@
 			}
 		}
 		// Replace the type of the state field.
-		Type fieldType = JavaCodeGenerator.getImplStateType(childRes.getParent());
+		Type fieldType = getImplStateType(childRes.getParent(), langSpec);
 		if (exp instanceof Term) {
 			((Term) exp).setType(fieldType);
 			for (Map.Entry<Position, Variable> varEnt: ((Term) exp).getVariables().entrySet()) {
@@ -634,38 +635,48 @@
 		return stateGetter;
 	}
 	
-	private MethodDeclaration declareStateGetterMethodInParent(ResourceNode resourceNode, TypeDeclaration parentComponent, Type resStateType, ILanguageSpecific langSpec) {
-		// Check duplication.
-		String getterName = getterPrefix + getComponentName(resourceNode.getResourceHierarchy(), langSpec);
-		for (MethodDeclaration method: parentComponent.getMethods()) {
-			if (method.getName().equals(getterName)) return null;
-		}
-		
-		// Declare the getter method of the resource state.
+	private MethodDeclaration declareStateGetterMethodInAncestor(ResourceNode resourceNode, Map<ResourceHierarchy, TypeDeclaration> resourceComponents, Type resStateType, ILanguageSpecific langSpec) {
+		// Search an ancestor in which the getter method is declared.
+		ResourceNode ancestorNode = resourceNode;
+		Stack<ResourceNode> ancestors = new Stack<>();
+		do {
+			ancestors.push(ancestorNode);
+			ancestorNode = ancestorNode.getParent();
+		} while (!generatesComponent(ancestorNode.getResourceHierarchy()));
+		TypeDeclaration ancestorComponent = resourceComponents.get(ancestorNode.getResourceHierarchy());
 		List<VariableDeclaration> getterParams = new ArrayList<>();
 		int v = 1;
-		for (Selector param: resourceNode.getSelectors()) {
-			if (param.getExpression() instanceof Variable) {
-				Variable var = (Variable) param.getExpression();
-				getterParams.add(new VariableDeclaration(var.getType(), var.getName()));
-			} else if (param.getExpression() instanceof Term) {
-				Term var = (Term) param.getExpression();
-				getterParams.add(new VariableDeclaration(var.getType(), "v" + v));
+		while (ancestors.size() > 0) {
+			ResourceNode curAncestor = ancestors.pop();
+			Expression param = curAncestor.getPrimaryResourcePath().getLastParam();
+			if (param instanceof Variable) {
+				Variable var = (Variable) param;
+				getterParams.add(langSpec.newVariableDeclaration(var.getType(), var.getName()));
+			} else if (param instanceof Term) {
+				Term var = (Term) param;
+				getterParams.add(langSpec.newVariableDeclaration(var.getType(), "v" + v));
 			}
 			v++;
 		}
+		// Check duplication.
+		String getterName = getterPrefix + getComponentName(resourceNode.getResourceHierarchy(), langSpec);
+		for (MethodDeclaration method: ancestorComponent.getMethods()) {
+			if (method.getName().equals(getterName) && method.getParameters().size() == getterParams.size()) return null;
+		}
+		
+		// Declare the getter method of the resource state.
 		MethodDeclaration stateGetter = null;
 		if (getterParams.size() == 0) {
-			stateGetter = new MethodDeclaration(getterName, resStateType);
+			stateGetter = langSpec.newMethodDeclaration(getterName, resStateType);
 		} else {
-			stateGetter = new MethodDeclaration(getterName, false, resStateType, getterParams);
+			stateGetter = langSpec.newMethodDeclaration(getterName, false, resStateType, getterParams);
 		}
-		if (parentComponent != null) {
-			parentComponent.addMethod(stateGetter);
+		if (ancestorComponent != null) {
+			ancestorComponent.addMethod(stateGetter);
 		}
 		
 		if (((StoreAttribute) resourceNode.getAttribute()).isStored()) {
-			fillChildGetterMethod(stateGetter, resourceNode.getResourceHierarchy(), resourceNode.getResourceHierarchy().getParent().getResourceStateType(), langSpec);
+			fillDescendantGetterMethod(stateGetter, resourceNode.getResourceHierarchy(), ancestorNode.getResourceHierarchy(), ancestorComponent, langSpec);
 		} else {	
 			addOtherGetterInvocationsToStateGatter(stateGetter, resourceNode, langSpec);
 		}
@@ -728,44 +739,51 @@
 		}
 	}
 	
-	private void declareChildGetterMethod(ResourceNode resourceNode, TypeDeclaration component, Map<ResourceHierarchy, Set<ResourceHierarchy>> childGetters, ILanguageSpecific langSpec) {
-		// Declare the getter methods in this resource to obtain the children resources.
-		Set<ResourceHierarchy> children = childGetters.get(resourceNode.getResourceHierarchy());
-		if (children == null) {
-			children = new HashSet<>();
-			childGetters.put(resourceNode.getResourceHierarchy(), children);
+	private void declareDescendantGetterMethods(ResourceNode resourceNode, TypeDeclaration component, Map<ResourceHierarchy, Set<ResourceHierarchy>> descendantGetters, ILanguageSpecific langSpec) {
+		// Declare the getter methods in this resource to obtain descendant resources.
+		Set<ResourceHierarchy> descendants = descendantGetters.get(resourceNode.getResourceHierarchy());
+		if (descendants == null) {
+			descendants = new HashSet<>();
+			descendantGetters.put(resourceNode.getResourceHierarchy(), descendants);
 		}
 		for (ResourceNode child: resourceNode.getChildren()) {
-			if (generatesComponent(child.getResourceHierarchy())) {
-				// A component for the child is generated.
-				if (!children.contains(child.getResourceHierarchy())) {
-					children.add(child.getResourceHierarchy());
-					List<VariableDeclaration> params = new ArrayList<>();
-					int v = 1;
-					Expression param = child.getPrimaryResourcePath().getLastParam();
-					if (param != null) {
-						if (param instanceof Variable) {
-							Variable var = (Variable) param;
-							params.add(langSpec.newVariableDeclaration(var.getType(), var.getName()));
-						} else if (param instanceof Term) {
-							Term var = (Term) param;
-							params.add(langSpec.newVariableDeclaration(var.getType(), "v" + v));
-						}
-						v++;
+			// A descendant of the child may generate a component.
+			List<VariableDeclaration> params = new ArrayList<>();
+			int v = 1;
+			ResourceNode descendant = child;
+			Set<ResourceNode> childNodes;
+			do {
+				Expression param = descendant.getPrimaryResourcePath().getLastParam();
+				if (param != null) {
+					if (param instanceof Variable) {
+						Variable var = (Variable) param;
+						params.add(langSpec.newVariableDeclaration(var.getType(), var.getName()));
+					} else if (param instanceof Term) {
+						Term var = (Term) param;
+						params.add(langSpec.newVariableDeclaration(var.getType(), "v" + v));
 					}
-					String childCompName = getComponentName(child.getResourceHierarchy(), langSpec);
-					Type childType = new Type(childCompName, childCompName);
-					MethodDeclaration childGetter = null;
-					if (params.size() == 0) {
-						childGetter = langSpec.newMethodDeclaration(getterPrefix + childCompName, childType);
-					} else {
-						childGetter = langSpec.newMethodDeclaration(getterPrefix + childCompName, false, childType, params);
-					}
-					
-					fillChildGetterMethod(childGetter, child.getResourceHierarchy(), resourceNode.getResourceStateType(), langSpec);
-					component.addMethod(childGetter);
+					v++;
 				}
-			}
+				if (generatesComponent(descendant.getResourceHierarchy())) {
+					// If the descendant generates a component.
+					if (!descendants.contains(descendant.getResourceHierarchy())) {
+						descendants.add(descendant.getResourceHierarchy());
+						String descendantCompName = getComponentName(descendant.getResourceHierarchy(), langSpec);
+						Type descendantType = new Type(descendantCompName, descendantCompName);
+						MethodDeclaration descendantGetter = null;
+						if (params.size() == 0) {
+							descendantGetter = langSpec.newMethodDeclaration(getterPrefix + descendantCompName, descendantType);
+						} else {
+							descendantGetter = langSpec.newMethodDeclaration(getterPrefix + descendantCompName, false, descendantType, params);
+						}
+						
+						fillDescendantGetterMethod(descendantGetter, descendant.getResourceHierarchy(), resourceNode.getResourceHierarchy(), component, langSpec);
+						component.addMethod(descendantGetter);
+					}
+					break;
+				}
+				childNodes = descendant.getChildren();
+			} while (childNodes != null && childNodes.size() == 1 && (descendant = childNodes.iterator().next()) != null);
 		}
 	}
 	
@@ -1439,7 +1457,7 @@
 							ResourcePath ref = rc.getResource();
 							if (!out.getResource().equals(ref)) {
 								String refVarName = ref.getLeafResourceName();
-								Expression refGetter = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(ref, null);
+								Expression refGetter = getPullAccessor().getDirectStateAccessorFor(ref, null);
 								String[] sideEffects = new String[] {""};
 								String refExp = refGetter.toImplementation(sideEffects);
 								String refTypeName = ref.getResourceStateType().getInterfaceTypeName();
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
index 8f17c1a..b646911 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaCodeGenerator.java
@@ -101,14 +101,14 @@
 					if (generatesComponent(child)) {
 						return new Type("List", "ArrayList<>", "List<" + getComponentName(child) + ">", DataConstraintModel.typeList);
 					} else {
-						return new Type("List", "ArrayList<>", "List<" + getImplStateType(child).getImplementationTypeName() + ">", DataConstraintModel.typeList);
+						return new Type("List", "ArrayList<>", "List<" + getImplStateType(child).getInterfaceTypeName() + ">", DataConstraintModel.typeList);
 					}
 				} else if (DataConstraintModel.typeMap.isAncestorOf(res.getResourceStateType())) {
 					// map.
 					if (generatesComponent(child)) {
 						return new Type("Map", "HashMap<>", "Map<String, " + getComponentName(child) + ">", DataConstraintModel.typeMap);
 					} else {
-						return new Type("Map", "HashMap<>", "Map<String, " + getImplStateType(child).getImplementationTypeName() + ">", DataConstraintModel.typeMap);
+						return new Type("Map", "HashMap<>", "Map<String, " + getImplStateType(child).getInterfaceTypeName() + ">", DataConstraintModel.typeMap);
 					}
 				}
 				return null;
@@ -120,9 +120,11 @@
 	}
 	
 	public static boolean generatesComponent(ResourceHierarchy res) {
-		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
-//		Type resType = res.getResourceStateType();
-//		return DataConstraintModel.typeJson.isAncestorOf(resType) || DataConstraintModel.typeList.isAncestorOf(resType) || DataConstraintModel.typeMap.isAncestorOf(resType);
+		if (res.getParent() == null) return true;
+		if (res.getChildren() == null || res.getChildren().size() == 0) return false;
+		if (res.getNumParameters() > 0 && res.getChildren().size() == 1 && res.getChildren().iterator().next().getNumParameters() > 0) return false;
+		return true;
+//		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
 	}
 
 	static public ArrayList<CompilationUnit> doGenerate(DataFlowGraph graph, DataTransferModel model) {
@@ -133,7 +135,7 @@
 		Map<ResourceHierarchy, Map<String, MethodDeclaration>> updates = new HashMap<>();
 		Map<ResourceHierarchy, Map<String, MethodDeclaration>> inputs = new HashMap<>();
 		List<Map.Entry<ResourceHierarchy, FieldDeclaration>> fields = new ArrayList<>();
-		Map<ResourceHierarchy, Set<ResourceHierarchy>> childGetters = new HashMap<>();
+		Map<ResourceHierarchy, Set<ResourceHierarchy>> descendantGetters = new HashMap<>();
 		List<Map.Entry<ResourceHierarchy, VariableDeclaration>> constructorParams = new ArrayList<>();
 
 		Map<ResourceHierarchy, Set<ResourceHierarchy>> dependedRootComponentGraph = getDependedRootComponentGraph(model);
@@ -275,41 +277,48 @@
 					declareAccessorMethodInMainComponent(resourceNode, mainComponent);
 				}
 				if (component != null) {
-					// Declare the getter methods to obtain the children resources.
-					Set<ResourceHierarchy> children = childGetters.get(resourceNode.getResourceHierarchy());
-					if (children == null) {
-						children = new HashSet<>();
-						childGetters.put(resourceNode.getResourceHierarchy(), children);
+					// Declare the getter methods in this resource to obtain descendant resources.
+					Set<ResourceHierarchy> descendants = descendantGetters.get(resourceNode.getResourceHierarchy());
+					if (descendants == null) {
+						descendants = new HashSet<>();
+						descendantGetters.put(resourceNode.getResourceHierarchy(), descendants);
 					}
 					for (ResourceNode child: resourceNode.getChildren()) {
-						if (generatesComponent(child.getResourceHierarchy())) {
-							// A component for the child is generated.
-							if (!children.contains(child.getResourceHierarchy())) {
-								children.add(child.getResourceHierarchy());
-								List<VariableDeclaration> params = new ArrayList<>();
-								int v = 1;
-								Expression param = child.getPrimaryResourcePath().getLastParam();
-								if (param != null) {
-									if (param instanceof Variable) {
-										Variable var = (Variable) param;
-										params.add(new VariableDeclaration(var.getType(), var.getName()));
-									} else if (param instanceof Term) {
-										Term var = (Term) param;
-										params.add(new VariableDeclaration(var.getType(), "v" + v));
-									}
-									v++;
+						// A descendant of the child may generate a component.
+						List<VariableDeclaration> params = new ArrayList<>();
+						int v = 1;
+						ResourceNode descendant = child;
+						Set<ResourceNode> childNodes;
+						do {
+							Expression param = descendant.getPrimaryResourcePath().getLastParam();
+							if (param != null) {
+								if (param instanceof Variable) {
+									Variable var = (Variable) param;
+									params.add(new VariableDeclaration(var.getType(), var.getName()));
+								} else if (param instanceof Term) {
+									Term var = (Term) param;
+									params.add(new VariableDeclaration(var.getType(), "v" + v));
 								}
-								String childCompName = getComponentName(child.getResourceHierarchy());
-								Type childType = new Type(childCompName, childCompName);
-								MethodDeclaration childGetter = null;
-								if (params.size() == 0) {
-									childGetter = new MethodDeclaration("get" + childCompName, childType);
-								} else {
-									childGetter = new MethodDeclaration("get" + childCompName, false, childType, params);
-								}
-								component.addMethod(childGetter);
+								v++;
 							}
-						}
+							if (generatesComponent(descendant.getResourceHierarchy())) {
+								// If the descendant generates a component.
+								if (!descendants.contains(descendant.getResourceHierarchy())) {
+									descendants.add(descendant.getResourceHierarchy());
+									String descendantCompName = getComponentName(descendant.getResourceHierarchy());
+									Type descendantType = new Type(descendantCompName, descendantCompName);
+									MethodDeclaration descendantGetter = null;
+									if (params.size() == 0) {
+										descendantGetter = new MethodDeclaration("get" + descendantCompName, descendantType);
+									} else {
+										descendantGetter = new MethodDeclaration("get" + descendantCompName, false, descendantType, params);
+									}
+									component.addMethod(descendantGetter);
+								}
+								break;
+							}
+							childNodes = descendant.getChildren();
+						} while (childNodes != null && childNodes.size() == 1 && (descendant = childNodes.iterator().next()) != null);
 					}
 				}
 			}
@@ -354,30 +363,40 @@
 				}
 			}
 			
-			// Declare the getter method to obtain the resource state in the parent component.
+			// Declare the getter method to obtain the resource state in an ancestor component.
 			if (component == null) {
 				// No component is created for this resource.
+				ResourceNode ancestorNode = resourceNode;
+				Stack<ResourceNode> ancestors = new Stack<>();
+				do {
+					ancestors.push(ancestorNode);
+					ancestorNode = ancestorNode.getParent();
+				} while (!generatesComponent(ancestorNode.getResourceHierarchy()));
+				List<VariableDeclaration> getterParams = new ArrayList<>();
+				int v = 1;
+				while (ancestors.size() > 0) {
+					ResourceNode curAncestor = ancestors.pop();
+					Expression param = curAncestor.getPrimaryResourcePath().getLastParam();
+					if (param instanceof Variable) {
+						Variable var = (Variable) param;
+						getterParams.add(new VariableDeclaration(var.getType(), var.getName()));
+					} else if (param instanceof Term) {
+						Term var = (Term) param;
+						getterParams.add(new VariableDeclaration(var.getType(), "v" + v));
+					}
+					v++;
+				}
 				String getterName = "get" + getComponentName(resourceNode.getResourceHierarchy());
 				boolean bExists = false;
 				for (Map.Entry<ResourceHierarchy, MethodDeclaration> entry: getters) {
-					if (entry.getKey() == resourceNode.getParent().getResourceHierarchy() && entry.getValue().getName().equals(getterName)) {
+					ResourceHierarchy r = entry.getKey();
+					MethodDeclaration m = entry.getValue();
+					if (r == ancestorNode.getResourceHierarchy() && m.getName().equals(getterName) && m.getParameters().size() == getterParams.size()) {
 						bExists = true;
 						break;
 					}
 				}
 				if (!bExists) {
-					List<VariableDeclaration> getterParams = new ArrayList<>();
-					int v = 1;
-					for (Selector param: resourceNode.getSelectors()) {
-						if (param.getExpression() instanceof Variable) {
-							Variable var = (Variable) param.getExpression();
-							getterParams.add(new VariableDeclaration(var.getType(), var.getName()));
-						} else if (param.getExpression() instanceof Term) {
-							Term var = (Term) param.getExpression();
-							getterParams.add(new VariableDeclaration(var.getType(), "v" + v));
-						}
-						v++;
-					}
 					Type resType = getImplStateType(resourceNode.getResourceHierarchy());
 					MethodDeclaration stateGetter = null;
 					if (getterParams.size() == 0) {
@@ -385,7 +404,7 @@
 					} else {
 						stateGetter = new MethodDeclaration(getterName, false, resType, getterParams);
 					}
-					getters.add(new AbstractMap.SimpleEntry<>(resourceNode.getParent().getResourceHierarchy(), stateGetter));
+					getters.add(new AbstractMap.SimpleEntry<>(ancestorNode.getResourceHierarchy(), stateGetter));
 					
 					// Declare the accessor method in the main type to call the getter method.
 					declareAccessorMethodInMainComponent(resourceNode, mainComponent);
@@ -1253,6 +1272,7 @@
 				// iterate from the root resource
 				Term getter = null;
 				int v = 1;
+				int arity = 2;
 				while (!pathStack.empty()) {
 					curPath = pathStack.pop();
 					String typeName = getComponentName(curPath.getResourceHierarchy());
@@ -1261,23 +1281,65 @@
 						String fieldName = toVariableName(typeName);
 						getter = new Field(fieldName, new Type(typeName, typeName));
 					} else {
-						Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
-						newGetter.addChild(getter);
-						if (curPath.getResourceHierarchy().getNumParameters() > 0) {
-							Variable var = null;
-							Expression param = curPath.getLastParam();
-							if (param instanceof Variable) {
-								var = (Variable) param;
-							} else if (param instanceof Term) {
-								var = new Variable("v" + v, ((Term) param).getType());
+						if (generatesComponent(curPath.getResourceHierarchy())) {
+							if (arity == 2) {
+								Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
+								newGetter.addChild(getter);
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									Variable var = null;
+									Expression param = curPath.getLastParam();
+									if (param instanceof Variable) {
+										var = (Variable) param;
+									} else if (param instanceof Term) {
+										var = new Variable("v" + v, ((Term) param).getType());
+									}
+									if (var != null) {
+										newGetter.addChild(var);
+										newGetter.getSymbol().setArity(2);
+									}
+									v++;
+								}
+								getter = newGetter;
+							} else {
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									Variable var = null;
+									Expression param = curPath.getLastParam();
+									if (param instanceof Variable) {
+										var = (Variable) param;
+									} else if (param instanceof Term) {
+										var = new Variable("v" + v, ((Term) param).getType());
+									}
+									if (var != null) {
+										getter.getSymbol().setArity(arity);
+										getter.addChild(var);
+									}
+									v++;
+								}
 							}
-							if (var != null) {
-								newGetter.addChild(var);
-								newGetter.getSymbol().setArity(2);
+							arity = 2;
+						} else {
+							// to get a descendant resource directly.
+							if (arity == 2) {
+								Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
+								newGetter.addChild(getter);
+								getter = newGetter;
 							}
-							v++;
+							if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+								Variable var = null;
+								Expression param = curPath.getLastParam();
+								if (param instanceof Variable) {
+									var = (Variable) param;
+								} else if (param instanceof Term) {
+									var = new Variable("v" + v, ((Term) param).getType());
+								}
+								if (var != null) {
+									getter.getSymbol().setArity(arity);
+									getter.addChild(var);
+									arity++;
+								}
+								v++;
+							}
 						}
-						getter = newGetter;
 					}
 				}
 				if (generatesComponent(targetRes.getResourceHierarchy())) {
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
index cbe262c..df180a0 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
@@ -575,10 +575,10 @@
 					}
 				}
 			}
+			
 			// for source nodes
 			TypeDeclaration mainComponent = componentMap.get(JavaCodeGenerator.mainTypeName);
 			for (ResourceHierarchy resource: model.getResourceHierarchies()) {
-//				ResourceNode resource = (ResourceNode) n;
 				String resourceName = JavaCodeGenerator.getComponentName(resource);
 				TypeDeclaration component = componentMap.get(resourceName);
 				if (component != null) {
@@ -637,36 +637,62 @@
 						}
 					}
 					
-					// child getter method
+					// descendant getter method
 					if (resource.getChildren().size() > 0) {
 						for (ResourceHierarchy child: resource.getChildren()) {
-							String methodName = "get" + JavaCodeGenerator.getComponentName(child);
-							MethodDeclaration childGetter = getMethod(component, methodName);
-							if (childGetter != null && (childGetter.getBody() == null || childGetter.getBody().getStatements().size() == 0)) {
-								if (DataConstraintModel.typeList.isAncestorOf(resource.getResourceStateType())) {
-									Term selector = new Term(DataConstraintModel.get);
-									selector.addChild(new Field("value"));
-									selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-									selector.setType(childGetter.getReturnType());
-									String[] sideEffects = new String[] {null};
-									String returnValue = selector.toImplementation(sideEffects);
-									if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-									childGetter.addStatement("return " + returnValue + ";");
-								} else if (DataConstraintModel.typeMap.isAncestorOf(resource.getResourceStateType())) {
-									Term selector = new Term(DataConstraintModel.lookup);
-									selector.addChild(new Field("value"));
-									selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-									selector.setType(childGetter.getReturnType());
-									String[] sideEffects = new String[] {null};
-									String returnValue = selector.toImplementation(sideEffects);
-									if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-									childGetter.addStatement("return " + returnValue+ ";");
-								} else {
-									String fieldName = JavaCodeGenerator.getComponentName(child);
-									String returnValue = JavaCodeGenerator.toVariableName(fieldName);
-									childGetter.addStatement("return this." + returnValue + ";");
-								}
+							ResourceHierarchy parent = resource;
+							ResourceHierarchy descendant = child;
+							Set<ResourceHierarchy> children;
+							Expression selector;
+							int params = 0;
+							if (DataConstraintModel.typeList.isAncestorOf(parent.getResourceStateType())) {
+								selector = new Field("value");
+								params++;
+							} else if (DataConstraintModel.typeMap.isAncestorOf(parent.getResourceStateType())) {
+								selector = new Field("value");
+								params++;
+							} else {
+								String fieldName = JavaCodeGenerator.getComponentName(descendant);
+								selector = new Field(JavaCodeGenerator.toVariableName(fieldName));
 							}
+							do {
+								String methodName = JavaCodeGenerator.getComponentName(descendant);
+								MethodDeclaration descendantGetter = null;
+								for (MethodDeclaration getter: getGetterMethods(component, methodName)) {
+									if ((getter.getParameters() == null && params == 0) || (getter.getParameters() != null && getter.getParameters().size() == params)) {
+										descendantGetter = getter;
+									}
+								}
+								if (descendantGetter != null) {
+									if (DataConstraintModel.typeList.isAncestorOf(parent.getResourceStateType())) {
+										Term newSelector = new Term(DataConstraintModel.get);
+										newSelector.addChild(selector);
+										newSelector.addChild(new Variable(descendantGetter.getParameters().get(descendantGetter.getParameters().size() - 1).getName()));
+										newSelector.setType(descendantGetter.getReturnType());
+										selector = newSelector;
+										params++;
+									} else if (DataConstraintModel.typeMap.isAncestorOf(parent.getResourceStateType())) {
+										Term newSelector = new Term(DataConstraintModel.lookup);
+										newSelector.addChild(selector);
+										newSelector.addChild(new Variable(descendantGetter.getParameters().get(descendantGetter.getParameters().size() - 1).getName()));
+										newSelector.setType(descendantGetter.getReturnType());
+										selector = newSelector;
+										params++;
+									}
+									if (descendantGetter != null && (descendantGetter.getBody() == null || descendantGetter.getBody().getStatements().size() == 0)) {
+										String[] sideEffects = new String[] {null};
+										String returnValue = selector.toImplementation(sideEffects);
+										if (sideEffects[0] != null) descendantGetter.addStatement(sideEffects[0]);
+										descendantGetter.addStatement("return " + returnValue + ";");
+									}
+								}
+								if (JavaCodeGenerator.generatesComponent(descendant)) {
+									// If the descendant generates a component.
+									break;
+								}
+								parent = descendant;
+								children = descendant.getChildren();
+							} while (children != null && children.size() == 1 && (descendant = children.iterator().next()) != null);
 						}
 					}
 				}
@@ -930,6 +956,16 @@
 		return null;
 	}
 	
+	private static List<MethodDeclaration> getGetterMethods(TypeDeclaration component, String resourceName) {
+		List<MethodDeclaration> getters = new ArrayList<>();
+		for (MethodDeclaration m: component.getMethods()) {
+			if (m.getName().startsWith("get" + resourceName)) {
+				getters.add(m);
+			}
+		}
+		return getters;
+	}
+	
 	private static Map<DataTransferChannel, Set<ChannelMember>> getIOChannelsAndMembers(ResourceHierarchy resource, DataTransferModel model) {
 		Map<DataTransferChannel, Set<ChannelMember>> ioChannelsAndMembers = new HashMap<>();
 		for (Channel c: model.getInputChannels()) {
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
index 5ced72d..0dc0551 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JerseyCodeGenerator.java
@@ -102,14 +102,14 @@
 					if (generatesComponent(child)) {
 						return new Type("List", "ArrayList<>", "List<" + getComponentName(child) + ">", DataConstraintModel.typeList);
 					} else {
-						return new Type("List", "ArrayList<>", "List<" + getImplStateType(child).getImplementationTypeName() + ">", DataConstraintModel.typeList);
+						return new Type("List", "ArrayList<>", "List<" + getImplStateType(child).getInterfaceTypeName() + ">", DataConstraintModel.typeList);
 					}
 				} else if (DataConstraintModel.typeMap.isAncestorOf(res.getResourceStateType())) {
 					// map.
 					if (generatesComponent(child)) {
 						return new Type("Map", "HashMap<>", "Map<String, " + getComponentName(child) + ">", DataConstraintModel.typeMap);
 					} else {
-						return new Type("Map", "HashMap<>", "Map<String, " + getImplStateType(child).getImplementationTypeName() + ">", DataConstraintModel.typeMap);
+						return new Type("Map", "HashMap<>", "Map<String, " + getImplStateType(child).getInterfaceTypeName() + ">", DataConstraintModel.typeMap);
 					}
 				}
 				return null;
@@ -121,9 +121,11 @@
 	}
 
 	public static boolean generatesComponent(ResourceHierarchy res) {
-		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
-//		Type resType = res.getResourceStateType();
-//		return DataConstraintModel.typeJson.isAncestorOf(resType) || DataConstraintModel.typeList.isAncestorOf(resType) || DataConstraintModel.typeMap.isAncestorOf(resType);
+		if (res.getParent() == null) return true;
+		if (res.getChildren() == null || res.getChildren().size() == 0) return false;
+		if (res.getNumParameters() > 0 && res.getChildren().size() == 1 && res.getChildren().iterator().next().getNumParameters() > 0) return false;
+		return true;
+//		return res.getParent() == null || !(res.getChildren() == null || res.getChildren().size() == 0);
 	}
 
 	static public ArrayList<CompilationUnit> doGenerate(DataFlowGraph graph, DataTransferModel model) {
@@ -136,7 +138,7 @@
 		Map<ResourceHierarchy, Map<String, MethodDeclaration>> updates = new HashMap<>();
 		Map<ResourceHierarchy, Map<String, MethodDeclaration>> inputs = new HashMap<>();
 		List<Map.Entry<ResourceHierarchy, FieldDeclaration>> fields = new ArrayList<>();
-		Map<ResourceHierarchy, Set<ResourceHierarchy>> childGetters = new HashMap<>();
+		Map<ResourceHierarchy, Set<ResourceHierarchy>> descendantGetters = new HashMap<>();
 		Map<ResourceHierarchy, MethodDeclaration> getterAccessors = new HashMap<>();
 		Map<ResourceHierarchy, MethodDeclaration> inputAccessors = new HashMap<>();
 		Map<ResourceHierarchy, Map<String, VariableDeclaration>> constructorParams = new HashMap<>();
@@ -221,41 +223,48 @@
 					component.addMethod(stateGetter);
 				}
 				if (component != null) {
-					// Declare the getter methods to obtain the children resources.
-					Set<ResourceHierarchy> children = childGetters.get(resourceNode.getResourceHierarchy());
-					if (children == null) {
-						children = new HashSet<>();
-						childGetters.put(resourceNode.getResourceHierarchy(), children);
+					// Declare the getter methods in this resource to obtain descendant resources.
+					Set<ResourceHierarchy> descendants = descendantGetters.get(resourceNode.getResourceHierarchy());
+					if (descendants == null) {
+						descendants = new HashSet<>();
+						descendantGetters.put(resourceNode.getResourceHierarchy(), descendants);
 					}
 					for (ResourceNode child: resourceNode.getChildren()) {
-						if (generatesComponent(child.getResourceHierarchy())) {
-							// The child generates a component.
-							if (!children.contains(child.getResourceHierarchy())) {
-								children.add(child.getResourceHierarchy());
-								List<VariableDeclaration> pathParams = new ArrayList<>();
-								int v = 1;
-								Expression pathParam = child.getPrimaryResourcePath().getLastParam();
-								if (pathParam != null) {
-									if (pathParam instanceof Variable) {
-										Variable var = (Variable) pathParam;
-										pathParams.add(new VariableDeclaration(var.getType(), var.getName()));
-									} else if (pathParam instanceof Term) {
-										Term var = (Term) pathParam;
-										pathParams.add(new VariableDeclaration(var.getType(), "v" + v));
-									}
-									v++;
+						// A descendant of the child may generate a component.
+						List<VariableDeclaration> pathParams = new ArrayList<>();
+						int v = 1;
+						ResourceNode descendant = child;
+						Set<ResourceNode> childNodes;
+						do {
+							Expression pathParam = descendant.getPrimaryResourcePath().getLastParam();
+							if (pathParam != null) {
+								if (pathParam instanceof Variable) {
+									Variable var = (Variable) pathParam;
+									pathParams.add(new VariableDeclaration(var.getType(), var.getName()));
+								} else if (pathParam instanceof Term) {
+									Term var = (Term) pathParam;
+									pathParams.add(new VariableDeclaration(var.getType(), "v" + v));
 								}
-								String childCompName = getComponentName(child.getResourceHierarchy());
-								Type childType = new Type(childCompName, childCompName);
-								MethodDeclaration childGetter = null;
-								if (pathParams.size() == 0) {
-									childGetter = new MethodDeclaration("get" + childCompName, childType);
-								} else {
-									childGetter = new MethodDeclaration("get" + childCompName, false, childType, pathParams);
-								}
-								component.addMethod(childGetter);
+								v++;
 							}
-						}
+							if (generatesComponent(descendant.getResourceHierarchy())) {
+								// If the descendant generates a component.
+								if (!descendants.contains(descendant.getResourceHierarchy())) {
+									descendants.add(descendant.getResourceHierarchy());
+									String descendantCompName = getComponentName(descendant.getResourceHierarchy());
+									Type descendantType = new Type(descendantCompName, descendantCompName);
+									MethodDeclaration descendantGetter = null;
+									if (pathParams.size() == 0) {
+										descendantGetter = new MethodDeclaration("get" + descendantCompName, descendantType);
+									} else {
+										descendantGetter = new MethodDeclaration("get" + descendantCompName, false, descendantType, pathParams);
+									}
+									component.addMethod(descendantGetter);
+								}
+								break;
+							}
+							childNodes = descendant.getChildren();
+						} while (childNodes != null && childNodes.size() == 1 && (descendant = childNodes.iterator().next()) != null);
 					}
 				}
 				
@@ -380,30 +389,40 @@
 				}
 			}
 			
-			// Declare the getter method to obtain the resource state in the parent component.
+			// Declare the getter method to obtain the resource state in an ancestor component.
 			if (component == null) {
 				// No component is created for this resource.			
+				ResourceNode ancestorNode = resourceNode;
+				Stack<ResourceNode> ancestors = new Stack<>();
+				do {
+					ancestors.push(ancestorNode);
+					ancestorNode = ancestorNode.getParent();
+				} while (!generatesComponent(ancestorNode.getResourceHierarchy()));
+				List<VariableDeclaration> pathParams = new ArrayList<>();
+				int v = 1;
+				while (ancestors.size() > 0) {
+					ResourceNode curAncestor = ancestors.pop();
+					Expression pathParam = curAncestor.getPrimaryResourcePath().getLastParam();
+					if (pathParam instanceof Variable) {
+						Variable var = (Variable) pathParam;
+						pathParams.add(new VariableDeclaration(var.getType(), var.getName()));
+					} else if (pathParam instanceof Term) {
+						Term var = (Term) pathParam;
+						pathParams.add(new VariableDeclaration(var.getType(), "v" + v));
+					}
+					v++;
+				}
 				String getterName = "get" + getComponentName(resourceNode.getResourceHierarchy());
 				boolean bExists = false;
 				for (Map.Entry<ResourceHierarchy, MethodDeclaration> entry: getters) {
-					if (entry.getKey() == resourceNode.getParent().getResourceHierarchy() && entry.getValue().getName().equals(getterName)) {
+					ResourceHierarchy r = entry.getKey();
+					MethodDeclaration m = entry.getValue();
+					if (r == ancestorNode.getResourceHierarchy() && m.getName().equals(getterName) && m.getParameters().size() == pathParams.size()) {
 						bExists = true;
 						break;
 					}
 				}
 				if (!bExists) {
-					List<VariableDeclaration> pathParams = new ArrayList<>();
-					int v = 1;
-					for (Selector pathParam: resourceNode.getSelectors()) {
-						if (pathParam.getExpression() instanceof Variable) {
-							Variable var = (Variable) pathParam.getExpression();
-							pathParams.add(new VariableDeclaration(var.getType(), var.getName()));
-						} else if (pathParam.getExpression() instanceof Term) {
-							Term var = (Term) pathParam.getExpression();
-							pathParams.add(new VariableDeclaration(var.getType(), "v" + v));
-						}
-						v++;
-					}
 					Type resType = getImplStateType(resourceNode.getResourceHierarchy());
 					MethodDeclaration stateGetter = null;
 					if (pathParams.size() == 0) {
@@ -411,7 +430,7 @@
 					} else {
 						stateGetter = new MethodDeclaration(getterName, false, resType, pathParams);
 					}
-					getters.add(new AbstractMap.SimpleEntry<>(resourceNode.getParent().getResourceHierarchy(), stateGetter));
+					getters.add(new AbstractMap.SimpleEntry<>(ancestorNode.getResourceHierarchy(), stateGetter));
 				}
 			}
 			
@@ -1288,6 +1307,7 @@
 				// iterate from the `from' resource
 				Term getter = null;
 				int v = 1;
+				int arity = 2;
 				while (!pathStack.empty()) {
 					curPath = pathStack.pop();
 					String typeName = getComponentName(curPath.getResourceHierarchy());
@@ -1296,23 +1316,65 @@
 						String fieldName = toVariableName(typeName);
 						getter = new Field(fieldName, new Type(typeName, typeName));
 					} else {
-						Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
-						newGetter.addChild(getter);
-						if (curPath.getResourceHierarchy().getNumParameters() > 0) {
-							Variable var = null;
-							Expression param = curPath.getLastParam();
-							if (param instanceof Variable) {
-								var = (Variable) param;
-							} else if (param instanceof Term) {
-								var = new Variable("v" + v, ((Term) param).getType());
+						if (generatesComponent(curPath.getResourceHierarchy())) {
+							if (arity == 2) {
+								Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
+								newGetter.addChild(getter);
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									Variable var = null;
+									Expression param = curPath.getLastParam();
+									if (param instanceof Variable) {
+										var = (Variable) param;
+									} else if (param instanceof Term) {
+										var = new Variable("v" + v, ((Term) param).getType());
+									}
+									if (var != null) {
+										newGetter.addChild(var);
+										newGetter.getSymbol().setArity(2);
+									}
+									v++;
+								}
+								getter = newGetter;
+							} else {
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									Variable var = null;
+									Expression param = curPath.getLastParam();
+									if (param instanceof Variable) {
+										var = (Variable) param;
+									} else if (param instanceof Term) {
+										var = new Variable("v" + v, ((Term) param).getType());
+									}
+									if (var != null) {
+										getter.getSymbol().setArity(arity);
+										getter.addChild(var);
+									}
+									v++;
+								}
 							}
-							if (var != null) {
-								newGetter.addChild(var);
-								newGetter.getSymbol().setArity(2);
+							arity = 2;
+						} else {
+							// to get a descendant resource directly.
+							if (arity == 2) {
+								Term newGetter = new Term(new Symbol("get" + typeName, -1, Symbol.Type.METHOD));
+								newGetter.addChild(getter);
+								getter = newGetter;
 							}
-							v++;
+							if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+								Variable var = null;
+								Expression param = curPath.getLastParam();
+								if (param instanceof Variable) {
+									var = (Variable) param;
+								} else if (param instanceof Term) {
+									var = new Variable("v" + v, ((Term) param).getType());
+								}
+								if (var != null) {
+									getter.getSymbol().setArity(arity);
+									getter.addChild(var);
+									arity++;
+								}
+								v++;
+							}
 						}
-						getter = newGetter;
 					}
 				}
 				
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
index a77cca1..d476588 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
@@ -700,6 +700,7 @@
 					}
 				}
 			}
+			
 			// for source nodes
 			for (ResourceHierarchy resource: model.getResourceHierarchies()) {
 				String resourceName = JerseyCodeGenerator.getComponentName(resource);
@@ -760,36 +761,62 @@
 						}
 					}
 					
-					// child getter method
+					// descendant getter method
 					if (resource.getChildren().size() > 0) {
 						for (ResourceHierarchy child: resource.getChildren()) {
-							String methodName = "get" + JerseyCodeGenerator.getComponentName(child);
-							MethodDeclaration childGetter = getMethod(component, methodName);
-							if (childGetter != null && (childGetter.getBody() == null || childGetter.getBody().getStatements().size() == 0)) {
-								if (DataConstraintModel.typeList.isAncestorOf(resource.getResourceStateType())) {
-									Term selector = new Term(DataConstraintModel.get);
-									selector.addChild(new Field("value"));
-									selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-									selector.setType(childGetter.getReturnType());
-									String[] sideEffects = new String[] {null};
-									String returnValue = selector.toImplementation(sideEffects);
-									if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-									childGetter.addStatement("return " + returnValue + ";");
-								} else if (DataConstraintModel.typeMap.isAncestorOf(resource.getResourceStateType())) {
-									Term selector = new Term(DataConstraintModel.lookup);
-									selector.addChild(new Field("value"));
-									selector.addChild(new Variable(childGetter.getParameters().get(childGetter.getParameters().size() - 1).getName()));
-									selector.setType(childGetter.getReturnType());
-									String[] sideEffects = new String[] {null};
-									String returnValue = selector.toImplementation(sideEffects);
-									if (sideEffects[0] != null) childGetter.addStatement(sideEffects[0]);
-									childGetter.addStatement("return " + returnValue+ ";");
-								} else {
-									String fieldName = JerseyCodeGenerator.getComponentName(child);
-									String returnValue = JerseyCodeGenerator.toVariableName(fieldName);
-									childGetter.addStatement("return this." + returnValue + ";");
-								}
+							ResourceHierarchy parent = resource;
+							ResourceHierarchy descendant = child;
+							Set<ResourceHierarchy> children;
+							Expression selector;
+							int params = 0;
+							if (DataConstraintModel.typeList.isAncestorOf(parent.getResourceStateType())) {
+								selector = new Field("value");
+								params++;
+							} else if (DataConstraintModel.typeMap.isAncestorOf(parent.getResourceStateType())) {
+								selector = new Field("value");
+								params++;
+							} else {
+								String fieldName = JerseyCodeGenerator.getComponentName(descendant);
+								selector = new Field(JerseyCodeGenerator.toVariableName(fieldName));
 							}
+							do {
+								String methodName = JerseyCodeGenerator.getComponentName(descendant);
+								MethodDeclaration descendantGetter = null;
+								for (MethodDeclaration getter: getGetterMethods(component, methodName)) {
+									if ((getter.getParameters() == null && params == 0) || (getter.getParameters() != null && getter.getParameters().size() == params)) {
+										descendantGetter = getter;
+									}
+								}
+								if (descendantGetter != null) {
+									if (DataConstraintModel.typeList.isAncestorOf(parent.getResourceStateType())) {
+										Term newSelector = new Term(DataConstraintModel.get);
+										newSelector.addChild(selector);
+										newSelector.addChild(new Variable(descendantGetter.getParameters().get(descendantGetter.getParameters().size() - 1).getName()));
+										newSelector.setType(descendantGetter.getReturnType());
+										selector = newSelector;
+										params++;
+									} else if (DataConstraintModel.typeMap.isAncestorOf(parent.getResourceStateType())) {
+										Term newSelector = new Term(DataConstraintModel.lookup);
+										newSelector.addChild(selector);
+										newSelector.addChild(new Variable(descendantGetter.getParameters().get(descendantGetter.getParameters().size() - 1).getName()));
+										newSelector.setType(descendantGetter.getReturnType());
+										selector = newSelector;
+										params++;
+									}
+									if (descendantGetter != null && (descendantGetter.getBody() == null || descendantGetter.getBody().getStatements().size() == 0)) {
+										String[] sideEffects = new String[] {null};
+										String returnValue = selector.toImplementation(sideEffects);
+										if (sideEffects[0] != null) descendantGetter.addStatement(sideEffects[0]);
+										descendantGetter.addStatement("return " + returnValue + ";");
+									}
+								}
+								if (JerseyCodeGenerator.generatesComponent(descendant)) {
+									// If the descendant generates a component.
+									break;
+								}
+								parent = descendant;
+								children = descendant.getChildren();
+							} while (children != null && children.size() == 1 && (descendant = children.iterator().next()) != null);
 						}
 					}					
 				}
@@ -1209,13 +1236,6 @@
 		return null;
 	}
 	
-	private static MethodDeclaration getGetterMethod(TypeDeclaration component, String resourceName) {
-		for (MethodDeclaration m: component.getMethods()) {
-			if (m.getName().startsWith("get" + resourceName)) return m;
-		}
-		return null;
-	}
-	
 	private static List<MethodDeclaration> getUpdateMethods(TypeDeclaration component, String resName) {
 		List<MethodDeclaration> updates = new ArrayList<>();
 		for (MethodDeclaration m: component.getMethods()) {
@@ -1232,6 +1252,23 @@
 		return updates;
 	}
 	
+	private static MethodDeclaration getGetterMethod(TypeDeclaration component, String resourceName) {
+		for (MethodDeclaration m: component.getMethods()) {
+			if (m.getName().startsWith("get" + resourceName)) return m;
+		}
+		return null;
+	}
+	
+	private static List<MethodDeclaration> getGetterMethods(TypeDeclaration component, String resourceName) {
+		List<MethodDeclaration> getters = new ArrayList<>();
+		for (MethodDeclaration m: component.getMethods()) {
+			if (m.getName().startsWith("get" + resourceName)) {
+				getters.add(m);
+			}
+		}
+		return getters;
+	}
+	
 	private static Map<DataTransferChannel, Set<ChannelMember>> getIOChannelsAndMembers(ResourceHierarchy resource, DataTransferModel model) {
 		Map<DataTransferChannel, Set<ChannelMember>> ioChannelsAndMembers = new HashMap<>();
 		for (Channel c: model.getInputChannels()) {
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/ResourceNode.java b/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/ResourceNode.java
index 6c2073c..d382534 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/ResourceNode.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/ResourceNode.java
@@ -160,6 +160,10 @@
 		return selectors;
 	}
 
+	public Selector getLastSelector() {
+		return selectors.get(resourceHierarchy.getTotalNumParameters() - 1);
+	}
+
 	public List<Selector> getAllSelectors() {
 		List<Selector> selectors = new ArrayList<>();
 		if (parent != null) {