diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaCodeGenerator.java
index de89ba5..4941a19 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaCodeGenerator.java
@@ -218,6 +218,17 @@
 									}
 								}
 							}
+						} else if (message.getClass() == Variable.class) {
+							MethodDeclaration input = new MethodDeclaration(
+									((Variable) cm.getStateTransition().getMessageExpression()).getName(),
+									false, typeVoid, null);
+							type.addMethod(input);
+							String str = ((Variable) cm.getStateTransition().getMessageExpression()).getName();
+							input = getMethod(mainType, str);
+							if (input == null) {
+								input = new MethodDeclaration(str, false, typeVoid, null);
+								mainType.addMethod(input);
+							}
 						}
 					}
 				}
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
index 2737c34..b2f0f0a 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
@@ -162,8 +162,7 @@
 					if (ioChannelAndMembers != null) {
 						Set<ChannelMember> outs = ioChannelAndMembers.getValue();
 						for (ChannelMember out: outs) {
-							Term message = (Term) out.getStateTransition().getMessageExpression();
-							MethodDeclaration input = getMethod(type, message.getSymbol().getName());
+							MethodDeclaration input = getInputMethod(type, out);
 							if (input != null) {
 								String[] sideEffects = new String[] {""};
 								Expression updateExp = ioChannelAndMembers.getKey().deriveUpdateExpressionOf(out, JavaCodeGenerator.pushAccessor);
@@ -182,9 +181,12 @@
 									if (mainInput != null) {
 										String args = "";
 										String delimitar = "";
-										for (Variable var: message.getVariables().values()) {
-											args += delimitar + var.getName();
-											delimitar = ", ";
+										if (out.getStateTransition().getMessageExpression() instanceof Term) {
+											Term message = (Term) out.getStateTransition().getMessageExpression();
+											for (Variable var: message.getVariables().values()) {
+												args += delimitar + var.getName();
+												delimitar = ", ";
+											}
 										}
 										mainInput.addStatement("this." + resourceName + "." + input.getName() + "(" + args + ");");
 									}
@@ -233,8 +235,7 @@
 			// I/O channel
 			for (ChannelMember out: ch.getOutputChannelMembers()) {
 				if (out.getIdentifierTemplate().equals(resource.getIdentifierTemplate())) {
-					if (out.getStateTransition().getMessageExpression() instanceof Term) {
-						// not an identity element
+					if (out.getStateTransition().getMessageExpression() instanceof Term || out.getStateTransition().getMessageExpression() instanceof Variable) {
 						channel = ch;
 						channelMembers.add(out);
 					}
@@ -251,18 +252,26 @@
 			// I/O channel
 			for (ChannelMember out: channel.getOutputChannelMembers()) {
 				if (out.getIdentifierTemplate().equals(resource.getIdentifierTemplate())) {
-					if (out.getStateTransition().getMessageExpression() instanceof Term) {
-						// not an identity element
-						Term message = (Term) out.getStateTransition().getMessageExpression();
-						MethodDeclaration input = getMethod(type, message.getSymbol().getName());
-						return input;
-					}
+					MethodDeclaration input = getInputMethod(type, out);
+					if (input != null) return input;
 				}
 			}
 		}
 		return null;
 	}
 
+	private static MethodDeclaration getInputMethod(TypeDeclaration type, ChannelMember out) {
+		MethodDeclaration input = null;
+		if (out.getStateTransition().getMessageExpression() instanceof Term) {
+			Term message = (Term) out.getStateTransition().getMessageExpression();
+			input = getMethod(type, message.getSymbol().getImplName());
+		} else if (out.getStateTransition().getMessageExpression() instanceof Variable) {
+			Variable message = (Variable) out.getStateTransition().getMessageExpression();
+			input = getMethod(type, message.getName());
+		}
+		return input;
+	}
+
 	private static MethodDeclaration getMethod(TypeDeclaration type, String methodName) {
 		for (MethodDeclaration m: type.getMethods()) {
 			if (m.getName().equals(methodName)) return m;
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyCodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyCodeGenerator.java
index 18556d6..4a1bf2e 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyCodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyCodeGenerator.java
@@ -149,6 +149,16 @@
 								input.addAnnotation(new Annotation("POST"));
 							}
 							type.addMethod(input);
+						} else if (message.getClass() == Variable.class) {
+							MethodDeclaration input = new MethodDeclaration(
+									((Variable) cm.getStateTransition().getMessageExpression()).getName(),
+									false, typeVoid, null);
+							if (cm.getStateTransition().isRightUnary()) {
+								input.addAnnotation(new Annotation("PUT"));
+							} else {
+								input.addAnnotation(new Annotation("POST"));
+							}
+							type.addMethod(input);
 						}
 					}
 				}
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
index 89446db..0007bcd 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
@@ -22,6 +22,7 @@
 import models.algebra.Type;
 import models.algebra.UnificationFailed;
 import models.algebra.ValueUndefined;
+import models.algebra.Variable;
 import models.dataConstraintModel.ChannelGenerator;
 import models.dataConstraintModel.ChannelMember;
 import models.dataConstraintModel.DataConstraintModel;
@@ -224,8 +225,7 @@
 					if (ioChannelAndMembers != null) {
 						Set<ChannelMember> outs = ioChannelAndMembers.getValue();
 						for (ChannelMember out: outs) {
-							Term message = (Term) out.getStateTransition().getMessageExpression();
-							MethodDeclaration input = getMethod(type, message.getSymbol().getName());
+							MethodDeclaration input = getInputMethod(type, out);
 							if (input != null) {
 								Expression updateExp = ioChannelAndMembers.getKey().deriveUpdateExpressionOf(out, JerseyCodeGenerator.pushAccessor);
 								String[] sideEffects = new String[] {""};
@@ -390,8 +390,7 @@
 			// I/O channel
 			for (ChannelMember out: ch.getOutputChannelMembers()) {
 				if (out.getIdentifierTemplate().equals(resource.getIdentifierTemplate())) {
-					if (out.getStateTransition().getMessageExpression() instanceof Term) {
-						// not an identity element
+					if (out.getStateTransition().getMessageExpression() instanceof Term || out.getStateTransition().getMessageExpression() instanceof Variable) {
 						channel = ch;
 						channelMembers.add(out);
 					}
@@ -408,18 +407,26 @@
 			// I/O channel
 			for (ChannelMember out: channel.getOutputChannelMembers()) {
 				if (out.getIdentifierTemplate().equals(resource.getIdentifierTemplate())) {
-					if (out.getStateTransition().getMessageExpression() instanceof Term) {
-						// not an identity element
-						Term message = (Term) out.getStateTransition().getMessageExpression();
-						MethodDeclaration input = getMethod(type, message.getSymbol().getName());
-						return input;
-					}
+					MethodDeclaration input = getInputMethod(type, out);
+					if (input != null) return input;
 				}
 			}
 		}
 		return null;
 	}
 
+	private static MethodDeclaration getInputMethod(TypeDeclaration type, ChannelMember out) {
+		MethodDeclaration input = null;
+		if (out.getStateTransition().getMessageExpression() instanceof Term) {
+			Term message = (Term) out.getStateTransition().getMessageExpression();
+			input = getMethod(type, message.getSymbol().getImplName());
+		} else if (out.getStateTransition().getMessageExpression() instanceof Variable) {
+			Variable message = (Variable) out.getStateTransition().getMessageExpression();
+			input = getMethod(type, message.getName());
+		}
+		return input;
+	}
+
 	private static MethodDeclaration getMethod(TypeDeclaration type, String methodName) {
 		for (MethodDeclaration m: type.getMethods()) {
 			if (m.getName().equals(methodName)) return m;
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
index e3493b5..011045a 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
@@ -157,13 +157,15 @@
 		
 		Expression messageTerm = getMessageExpression();
 		HashMap<Position, Variable> messageVars = messageTerm.getVariables();
-		for (Entry<Position, Variable> messageVarEnt: messageVars.entrySet()) {
-			Variable var = messageVarEnt.getValue();
-			Position varPos = messageVarEnt.getKey();
-			Expression valueCalc = concreteMessage.getSubTerm(varPos);
-			if (valueCalc != null) {
-				if (bindings.get(var) != null) throw new ResolvingMultipleDefinitionIsFutureWork();
-				bindings.put(var, valueCalc);
+		if (concreteMessage != null) {
+			for (Entry<Position, Variable> messageVarEnt: messageVars.entrySet()) {
+				Variable var = messageVarEnt.getValue();
+				Position varPos = messageVarEnt.getKey();
+				Expression valueCalc = concreteMessage.getSubTerm(varPos);
+				if (valueCalc != null) {
+					if (bindings.get(var) != null) throw new ResolvingMultipleDefinitionIsFutureWork();
+					bindings.put(var, valueCalc);
+				}
 			}
 		}
 		
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/DataflowChannelGenerator.java b/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/DataflowChannelGenerator.java
index 2839622..40dd36d 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/DataflowChannelGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataFlowModel/DataflowChannelGenerator.java
@@ -219,7 +219,9 @@
 		Expression curOutputStateAccessor = stateAccessor.getCurrentStateAccessorFor(targetIdentifier, targetIdentifier);
 		if (unifiedMessage == null) {
 			// for IOChannel
-			unifiedMessage = (Term) targetMember.getStateTransition().getMessageExpression();
+			if (targetMember.getStateTransition().getMessageExpression() instanceof Term) {
+				unifiedMessage = (Term) targetMember.getStateTransition().getMessageExpression();
+			}
 		}
 		return targetMember.getStateTransition().deriveNextStateExpressionFor(curOutputStateAccessor, unifiedMessage);
 	}