diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
index 015baa7..f4a867b 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
@@ -50,8 +50,9 @@
  */
 public abstract class CodeGenerator {
 	public static final String fieldOfResourceState = "value";
+	public static final String methoNameOfResourceState = "Value";
 	public static final String getterPrefix = "get";
-	public static final String getterOfResourceState = "getValue";
+	public static final String getterOfResourceState = getterPrefix + methoNameOfResourceState;		// "getValue"
 	public static final String updateMethodPrefix = "update";
 	public static final String from = "From";
 	public static final String _for = "For";
@@ -408,7 +409,7 @@
 		}
 	}
 
-	protected void declareAccessorInMainComponent(TypeDeclaration mainComponent, ResourceNode accessRes, MethodDeclaration stateGetter, ILanguageSpecific langSpec) {
+	protected void declareAccessorInMainComponent(TypeDeclaration mainComponent, ResourceNode accessRes, MethodDeclaration stateGetter, IPlatformSpecific platformSpec, ILanguageSpecific langSpec) {
 		List<VariableDeclaration> mainGetterParams = new ArrayList<>();
 		int v = 1;
 		for (Expression param: accessRes.getPrimaryResourcePath().getPathParams()) {
@@ -428,7 +429,7 @@
 			accessor = langSpec.newMethodDeclaration(getterPrefix + getComponentName(accessRes.getResourceHierarchy(), langSpec), false, getImplStateType(accessRes.getResourceHierarchy(), langSpec), mainGetterParams);
 		}
 		Block block = new Block();
-		Expression getState = getPullAccessor().getDirectStateAccessorFor(accessRes.getPrimaryResourcePath(), null);
+		Expression getState = getPullAccessor(platformSpec).getDirectStateAccessorFor(accessRes.getPrimaryResourcePath(), null);
 		block.addStatement(langSpec.getReturnStatement(getState.toImplementation(new String[] {null})) + langSpec.getStatementDelimiter());
 //		if (stateGetter.getParameters() == null || stateGetter.getParameters().size() == 0) {
 //			block.addStatement(langSpec.getReturnStatement(langSpec.getMethodInvocation(accessRes.getResourceName(), stateGetter.getName())) + langSpec.getStatementDelimiter());
@@ -513,244 +514,440 @@
 		return null;
 	}
 
-	protected IResourceStateAccessor getPushAccessor() {
-		return new IResourceStateAccessor() {
-			@Override
-			public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				ResourcePath fromRes= from.getResource();
-				if (targetRes.equals(fromRes)) {
-					return new Field(fieldOfResourceState,
+	protected IResourceStateAccessor getPushAccessor(IPlatformSpecific platformSpec) {
+		if (platformSpec.isMonolithic()) {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					ResourcePath fromRes= from.getResource();
+					if (targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					// use the cached value as the current state
+					return new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
 							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
 									: DataConstraintModel.typeInt);
 				}
-				// use the cached value as the current state
-				return new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
-
-			@Override
-			public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
-
-			@Override
-			public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
-				if (fromRes != null && targetRes.equals(fromRes)) {
-					return new Field(fieldOfResourceState,
+	
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
 							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
 									: DataConstraintModel.typeInt);
 				}
-				// for reference channel member
-				return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
-		};
+	
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null && targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					// for reference channel member
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+			};
+		} else {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					ResourcePath fromRes = from.getResource();
+					if (targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					// use the cached value as the current state
+					return new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null && targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					return null;
+				}
+			};
+		}
 	}
 
-	protected IResourceStateAccessor getPullAccessor() {
-		return new IResourceStateAccessor() {
-			@Override
-			public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				if (from != null) {
-					ResourcePath fromRes= from.getResource();
-					if (!target.isOutside()) {
-						return getDirectStateAccessorFor(targetRes, fromRes);
-					}
-					Term getter = null;
-					String targetComponentName = getComponentName(targetRes.getResourceHierarchy(), langSpec);
-					if (generatesComponent(targetRes.getResourceHierarchy())) {
-						getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
-						getter.addChild(new Field(langSpec.toVariableName(targetComponentName), targetRes.getResourceStateType()));
+	protected IResourceStateAccessor getPullAccessor(IPlatformSpecific platformSpec) {
+		if (platformSpec.isMonolithic()) {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					if (from != null) {
+						ResourcePath fromRes= from.getResource();
+						if (!target.isOutside()) {
+							return getDirectStateAccessorFor(targetRes, fromRes);
+						}
+						Term getter = null;
+						String targetComponentName = getComponentName(targetRes.getResourceHierarchy(), langSpec);
+						if (generatesComponent(targetRes.getResourceHierarchy())) {
+							getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
+							getter.addChild(new Field(langSpec.toVariableName(targetComponentName), targetRes.getResourceStateType()));
+						} else {
+							String parentName = langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy().getParent(), langSpec));
+							Type parentType = targetRes.getResourceHierarchy().getParent().getResourceStateType();
+							getter = new Term(new Symbol(getterPrefix + targetComponentName, 1, Symbol.Type.METHOD));
+							getter.addChild(new Field(parentName, parentType));
+						}
+						return getter;
 					} else {
-						String parentName = langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy().getParent(), langSpec));
-						Type parentType = targetRes.getResourceHierarchy().getParent().getResourceStateType();
-						getter = new Term(new Symbol(getterPrefix + targetComponentName, 1, Symbol.Type.METHOD));
-						getter.addChild(new Field(parentName, parentType));
+						return getDirectStateAccessorFor(targetRes, null);
+					}
+				}
+	
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					if (from != null) {
+						ResourcePath fromRes= from.getResource();
+						if (!target.isOutside()) {
+							return getDirectStateAccessorFor(targetRes, fromRes);
+						}
+						Term getter = null;
+						String targetComponentName = getComponentName(targetRes.getResourceHierarchy(), langSpec);
+						if (generatesComponent(targetRes.getResourceHierarchy())) {
+							getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
+							getter.addChild(new Field(langSpec.toVariableName(targetComponentName), targetRes.getResourceStateType()));
+						} else {
+							String parentName = langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy().getParent(), langSpec));
+							Type parentType = targetRes.getResourceHierarchy().getParent().getResourceStateType();
+							getter = new Term(new Symbol(getterPrefix + targetComponentName, 1, Symbol.Type.METHOD));
+							getter.addChild(new Field(parentName, parentType));
+						}
+						return getter;
+					} else {
+						return getDirectStateAccessorFor(targetRes, null);
+					}
+				}
+				
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null) {
+						if (targetRes.equals(fromRes)) {
+							return new Field(fieldOfResourceState,
+									targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+											: DataConstraintModel.typeInt);
+						}
+						// for reference channel member
+						if (fromRes.isAncestorOf(targetRes)) {
+							Stack<ResourcePath> pathStack = new Stack<>();
+							ResourcePath curPath = targetRes;
+							do {
+								pathStack.push(curPath);
+								curPath = curPath.getParent();					
+							} while (!curPath.equals(fromRes));
+							// iterate from the fromRes resource
+							return getRelativePath(targetRes, pathStack);
+						}
+						if (generatesComponent(targetRes.getResourceHierarchy())) {
+							Term getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
+							getter.addChild(new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)), targetRes.getResourceStateType()));
+							return getter;
+						} else {
+							return new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)), targetRes.getResourceStateType());
+						}
+					} else {
+						// (#3) access from the outside of the hierarchy (must be kept consistent with #4)
+						Stack<ResourcePath> pathStack = new Stack<>();
+						ResourcePath curPath = targetRes;
+						do {
+							pathStack.push(curPath);
+							curPath = curPath.getParent();					
+						} while (curPath != null);
+						// iterate from the root resource
+						return getRelativePath(targetRes, pathStack);
+					}
+				}
+	
+				private Expression getRelativePath(ResourcePath targetRes, Stack<ResourcePath> pathStack) {
+					ResourcePath curPath;
+					Term getter = null;
+					int arity = 2;
+					boolean doesChainInvocations = true;
+					while (!pathStack.empty()) {
+						curPath = pathStack.pop();
+						String typeName = getComponentName(curPath.getResourceHierarchy(), langSpec);
+						if (getter == null && generatesComponent(curPath.getResourceHierarchy())) {
+							// root resource
+							String fieldName = langSpec.toVariableName(typeName);
+							getter = new Field(fieldName, new Type(typeName, typeName));
+						} else {
+							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) {
+										Expression param = curPath.getLastParam();
+										if (param != null) {
+											newGetter.addChild(param);
+											newGetter.getSymbol().setArity(2);
+										}
+									}
+									getter = newGetter;
+								} else {
+									// add the last path parameter.
+									if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+										Expression param = curPath.getLastParam();
+										if (param != null) {
+											getter.getSymbol().setArity(arity);
+											getter.addChild(param);
+										}
+									}
+								}
+								arity = 2;
+								doesChainInvocations = true;
+							} else {
+								// to get a descendant resource directly. (e.g, .todos.{year}.{month}.{day}.{id} ==> .getTodos().getTodo(year, month, day, id))
+								if (doesChainInvocations) {
+									Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
+									newGetter.addChild(getter);
+									getter = newGetter;
+									doesChainInvocations = false;
+								}
+								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+									// may change the symbol name
+									getter.getSymbol().changeName(getterPrefix + typeName);
+									// add a path parameter.
+									Expression param = curPath.getLastParam();
+									if (param != null) {
+										getter.getSymbol().setArity(arity);
+										getter.addChild(param);
+										arity++;
+									}
+								}
+							}
+						}
+					}
+					
+					if (generatesComponent(targetRes.getResourceHierarchy())) {
+						Term newGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
+						newGetter.addChild(getter);
+						getter = newGetter;
 					}
 					return getter;
-				} else {
-					return getDirectStateAccessorFor(targetRes, null);
 				}
-			}
+			};
+		} else {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					if (from != null && !target.isOutside()) {
+						ResourcePath fromRes = from.getResource();
+						if (targetRes.getCommonPrefix(fromRes) != null) {
+							return getDirectStateAccessorFor(targetRes, fromRes);
+						}
+					}
+					// for reference channel member
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
 
-			@Override
-			public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				if (from != null) {
-					ResourcePath fromRes= from.getResource();
-					if (!target.isOutside()) {
-						return getDirectStateAccessorFor(targetRes, fromRes);
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					if (from != null && !target.isOutside()) {
+						ResourcePath fromRes = from.getResource();
+						if (targetRes.getCommonPrefix(fromRes) != null) {
+							return getDirectStateAccessorFor(targetRes, fromRes);
+						}
 					}
-					Term getter = null;
-					String targetComponentName = getComponentName(targetRes.getResourceHierarchy(), langSpec);
-					if (generatesComponent(targetRes.getResourceHierarchy())) {
-						getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
-						getter.addChild(new Field(langSpec.toVariableName(targetComponentName), targetRes.getResourceStateType()));
-					} else {
-						String parentName = langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy().getParent(), langSpec));
-						Type parentType = targetRes.getResourceHierarchy().getParent().getResourceStateType();
-						getter = new Term(new Symbol(getterPrefix + targetComponentName, 1, Symbol.Type.METHOD));
-						getter.addChild(new Field(parentName, parentType));
-					}
-					return getter;
-				} else {
-					return getDirectStateAccessorFor(targetRes, null);
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
 				}
-			}
-			
-			@Override
-			public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
-				if (fromRes != null) {
+				
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null && !fromRes.getResourceHierarchy().isAncestorOf(targetRes.getResourceHierarchy())) {
+						if (targetRes.equals(fromRes)) {
+							return new Field(fieldOfResourceState,
+									targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+											: DataConstraintModel.typeInt);
+						}
+						// for reference channel member
+						return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					} else {
+						// (#3) access from an ancestor or outside of the hierarchy (must be kept consistent with #4)
+						Stack<ResourcePath> pathStack = new Stack<>();
+						ResourcePath curPath = targetRes;
+						do {
+							if (fromRes != null && curPath.equals(fromRes)) break;
+							pathStack.push(curPath);
+							curPath = curPath.getParent();					
+						} while (curPath != null);
+						// iterate from the `from' resource
+						Term getter = null;
+						int arity = 2;
+						boolean doesChainInvocations = true;
+						while (!pathStack.empty()) {
+							curPath = pathStack.pop();
+							String typeName = getComponentName(curPath.getResourceHierarchy(), langSpec);
+							if (getter == null && fromRes == null) {
+								// root resource
+								String fieldName = langSpec.toVariableName(typeName);
+								getter = new Field(fieldName, new Type(typeName, typeName));
+							} else {
+								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) {
+											Expression param = curPath.getLastParam();
+											if (param != null) {
+												newGetter.addChild(param);
+												newGetter.getSymbol().setArity(2);
+											}
+										}
+										getter = newGetter;
+									} else {
+										// add the last path parameter.
+										if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+											Expression param = curPath.getLastParam();
+											if (param != null) {
+												getter.getSymbol().setArity(arity);
+												getter.addChild(param);
+											}
+										}
+									}
+									arity = 2;
+									doesChainInvocations = true;
+								} else {
+									// to get a descendant resource directly. (e.g, .todos.{year}.{month}.{day}.{id} ==> .getTodos().getTodo(year, month, day, id))
+									if (doesChainInvocations) {
+										Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
+										newGetter.addChild(getter);
+										getter = newGetter;
+										doesChainInvocations = false;
+									}
+									if (curPath.getResourceHierarchy().getNumParameters() > 0) {
+										// may change the symbol name
+										getter.getSymbol().changeName(getterPrefix + typeName);
+										// add a path parameter.
+										Expression param = curPath.getLastParam();
+										if (param != null) {
+											getter.getSymbol().setArity(arity);
+											getter.addChild(param);
+											arity++;
+										}
+									}
+								}
+							}
+						}
+						
+						if (generatesComponent(targetRes.getResourceHierarchy())) {
+							Term newGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
+							newGetter.addChild(getter);
+							getter = newGetter;
+						}
+						return getter;
+					}
+				}
+			};
+		}
+	}
+	
+	protected IResourceStateAccessor getRefAccessor(IPlatformSpecific platformSpec) {
+		if (platformSpec.isMonolithic()) {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					ResourcePath fromRes= from.getResource();
+					if (targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					// use the cached value as the current state
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+	
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes= target.getResource();
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+	
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null && targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					// for reference channel member
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
+							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+									: DataConstraintModel.typeInt);
+				}
+			};
+		} else {
+			return new IResourceStateAccessor() {
+				@Override
+				public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					ResourcePath fromRes = from.getResource();
 					if (targetRes.equals(fromRes)) {
 						return new Field(fieldOfResourceState,
 								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
 										: DataConstraintModel.typeInt);
 					}
 					// for reference channel member
-					if (fromRes.isAncestorOf(targetRes)) {
-						Stack<ResourcePath> pathStack = new Stack<>();
-						ResourcePath curPath = targetRes;
-						do {
-							pathStack.push(curPath);
-							curPath = curPath.getParent();					
-						} while (!curPath.equals(fromRes));
-						// iterate from the fromRes resource
-						return getRelativePath(targetRes, pathStack);
-					}
-					if (generatesComponent(targetRes.getResourceHierarchy())) {
-						Term getter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
-						getter.addChild(new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)), targetRes.getResourceStateType()));
-						return getter;
-					} else {
-						return new Field(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)), targetRes.getResourceStateType());
-					}
-				} else {
-					// (#3) access from the outside of the hierarchy (must be kept consistent with #4)
-					Stack<ResourcePath> pathStack = new Stack<>();
-					ResourcePath curPath = targetRes;
-					do {
-						pathStack.push(curPath);
-						curPath = curPath.getParent();					
-					} while (curPath != null);
-					// iterate from the root resource
-					return getRelativePath(targetRes, pathStack);
-				}
-			}
-
-			private Expression getRelativePath(ResourcePath targetRes, Stack<ResourcePath> pathStack) {
-				ResourcePath curPath;
-				Term getter = null;
-				int arity = 2;
-				boolean doesChainInvocations = true;
-				while (!pathStack.empty()) {
-					curPath = pathStack.pop();
-					String typeName = getComponentName(curPath.getResourceHierarchy(), langSpec);
-					if (getter == null && generatesComponent(curPath.getResourceHierarchy())) {
-						// root resource
-						String fieldName = langSpec.toVariableName(typeName);
-						getter = new Field(fieldName, new Type(typeName, typeName));
-					} else {
-						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) {
-									Expression param = curPath.getLastParam();
-									if (param != null) {
-										newGetter.addChild(param);
-										newGetter.getSymbol().setArity(2);
-									}
-								}
-								getter = newGetter;
-							} else {
-								// add the last path parameter.
-								if (curPath.getResourceHierarchy().getNumParameters() > 0) {
-									Expression param = curPath.getLastParam();
-									if (param != null) {
-										getter.getSymbol().setArity(arity);
-										getter.addChild(param);
-									}
-								}
-							}
-							arity = 2;
-							doesChainInvocations = true;
-						} else {
-							// to get a descendant resource directly. (e.g, .todos.{year}.{month}.{day}.{id} ==> .getTodos().getTodo(year, month, day, id))
-							if (doesChainInvocations) {
-								Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
-								newGetter.addChild(getter);
-								getter = newGetter;
-								doesChainInvocations = false;
-							}
-							if (curPath.getResourceHierarchy().getNumParameters() > 0) {
-								// may change the symbol name
-								getter.getSymbol().changeName("get" + typeName);
-								// add a path parameter.
-								Expression param = curPath.getLastParam();
-								if (param != null) {
-									getter.getSymbol().setArity(arity);
-									getter.addChild(param);
-									arity++;
-								}
-							}
-						}
-					}
-				}
-				
-				if (generatesComponent(targetRes.getResourceHierarchy())) {
-					Term newGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
-					newGetter.addChild(getter);
-					getter = newGetter;
-				}
-				return getter;
-			}
-		};
-	}
-	
-	protected IResourceStateAccessor getRefAccessor() {
-		return new IResourceStateAccessor() {
-			@Override
-			public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				ResourcePath fromRes= from.getResource();
-				if (targetRes.equals(fromRes)) {
-					return new Field(fieldOfResourceState,
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
 							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
 									: DataConstraintModel.typeInt);
 				}
-				// use the cached value as the current state
-				return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
 
-			@Override
-			public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
-				ResourcePath targetRes= target.getResource();
-				return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
-
-			@Override
-			public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
-				if (fromRes != null && targetRes.equals(fromRes)) {
-					return new Field(fieldOfResourceState,
+				@Override
+				public Expression getNextStateAccessorFor(ChannelMember target, ChannelMember from) {
+					ResourcePath targetRes = target.getResource();
+					return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
 							targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
 									: DataConstraintModel.typeInt);
 				}
-				// for reference channel member
-				return new Parameter(langSpec.toVariableName(getComponentName(targetRes.getResourceHierarchy(), langSpec)),
-						targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
-								: DataConstraintModel.typeInt);
-			}
-		};
+
+				@Override
+				public Expression getDirectStateAccessorFor(ResourcePath targetRes, ResourcePath fromRes) {
+					if (fromRes != null && targetRes.equals(fromRes)) {
+						return new Field(fieldOfResourceState,
+								targetRes.getResourceStateType() != null ? targetRes.getResourceStateType()
+										: DataConstraintModel.typeInt);
+					}
+					return null;
+				}
+			};
+		}
 	}
 }