diff --git a/src/main/java/haflow/engine/oozie/OozieEngine.java b/src/main/java/haflow/engine/oozie/OozieEngine.java
index 12fb43f..33a34b0 100644
--- a/src/main/java/haflow/engine/oozie/OozieEngine.java
+++ b/src/main/java/haflow/engine/oozie/OozieEngine.java
@@ -8,7 +8,9 @@ import haflow.engine.AbstractEngine;
 import haflow.engine.Engine;
 import haflow.engine.RunFlowResult;
 import haflow.engine.ValidateFlowResult;
+import haflow.engine.model.AdjMatrixNode;
 import haflow.engine.model.DirectedGraph;
+import haflow.module.DataType;
 import haflow.module.Module;
 import haflow.module.ModuleConfiguration;
 import haflow.module.ModuleEndpoint;
@@ -17,6 +19,7 @@ import haflow.service.HdfsService;
 import haflow.service.NodeConfigurationService;
 import haflow.util.ClusterConfiguration;
 
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -49,8 +52,9 @@ public class OozieEngine extends AbstractEngine {
 			Map<UUID, Class<?>> moduleClasses = this.moduleUtil
 					.searchForModuleClasses();
 			
+			DirectedGraph originalGraph = new DirectedGraph(flow.getNodes(), flow.getEdges());
 			messageBuilder.append("Start validating flow inputs and outputs ...");
-			boolean isValidGraph = true;//validateGraph(graph, moduleClasses, messageBuilder);//TODO
+			boolean isValidGraph = validateGraph(originalGraph, moduleClasses, messageBuilder);//TODO
 			if (isValidGraph) {
 				messageBuilder.append(" done"  + "<br>");
 				
@@ -63,7 +67,7 @@ public class OozieEngine extends AbstractEngine {
 					String flowName = flow.getName();
 					String workflowXml = null;
 					try {
-						workflowXml = this.oozieFlowXmlGenerator.genWorkflowXml(flow, moduleClasses, messageBuilder);
+						workflowXml = this.oozieFlowXmlGenerator.genWorkflowXml(flow, originalGraph, moduleClasses, messageBuilder);
 					} catch (Exception e) {
 						messageBuilder.append(e.getMessage());
 					}
@@ -146,10 +150,89 @@ public class OozieEngine extends AbstractEngine {
 		return jarPaths;
 	}
 
+	/**
+	 * validate graph 
+	 * @param graph
+	 * @param moduleClasses
+	 * @param messageBuilder
+	 * @return
+	 */
 	private boolean validateGraph(DirectedGraph graph,
 			Map<UUID, Class<?>> moduleClasses, StringBuilder messageBuilder) {
+		boolean idtm = isDataTypeMatch(graph, moduleClasses, messageBuilder);
+		if(idtm == false)
+			return false;
+		boolean veio = hasNoEmptyInputOutput(graph, moduleClasses, messageBuilder);
+		if( veio == false)
+			return false;
+		return true;
+		
+	}
+	
+	private boolean isDataTypeMatch(DirectedGraph graph,
+			Map<UUID, Class<?>> moduleClasses, StringBuilder messageBuilder){
 		List<Edge> edges = graph.getEdgeList();
 
+		Map<Edge, DataType> sourceDataTypeMap = new HashMap<Edge, DataType>();
+		Map<Edge, DataType> targetDataTypeMap = new HashMap<Edge, DataType>();
+		
+		for( Edge edge : edges ){
+			Node sourceNode = edge.getSourceNode();
+			Class<?> sourceNodeModuleClass = moduleClasses.get(sourceNode.getModuleId());
+			Module sourceNodeModule = sourceNodeModuleClass.getAnnotation(Module.class);
+			ModuleEndpoint[] outputs = sourceNodeModule.outputs();
+			DataType sourceEndPointDataType = null;
+			for( ModuleEndpoint output : outputs){
+				if( output.name().equals(edge.getSourceEndpoint()) ){
+					sourceEndPointDataType = output.dataType();
+				}
+			}
+			
+			Node targetNode = edge.getTargetNode();
+			Class<?> targetNodeModuleClass = moduleClasses.get(targetNode.getModuleId());
+			Module targetNodeModule = targetNodeModuleClass.getAnnotation(Module.class);
+			ModuleEndpoint[] inputs = targetNodeModule.inputs();
+			DataType targetEndPointDataType = null;
+			for( ModuleEndpoint input : inputs ){
+				if( input.name().equals(edge.getTargetEndpoint())){
+					targetEndPointDataType = input.dataType();
+				}
+			}
+			
+			if( !sourceDataTypeMap.containsKey(edge)){
+				sourceDataTypeMap.put(edge, sourceEndPointDataType);
+			}
+			if(targetEndPointDataType == DataType.AUTO){
+				int nodeIndex = graph.getNodeIndex(targetNode);
+				List<AdjMatrixNode> adjEdges = graph.getAdjacent(nodeIndex);
+				for(AdjMatrixNode adjEdge : adjEdges ){
+					targetDataTypeMap.put(adjEdge.getPath(), sourceEndPointDataType);
+				}
+			}else{
+				if( !targetDataTypeMap.containsKey(edge)){
+					targetDataTypeMap.put(edge, targetEndPointDataType);
+				}
+			}
+		}
+		
+		//validate data type of each edge
+		for( Edge edge : edges ){
+			DataType sourceEndPointDataType = sourceDataTypeMap.get(edge);
+			DataType targetEndPointDataType = targetDataTypeMap.get(edge);
+			
+			if( !DataType.matches(sourceEndPointDataType, targetEndPointDataType) ){
+				messageBuilder.append("<br>" + "Data type mismatch: " + edge.getSourceNode().getName() + "." + 
+					edge.getSourceEndpoint() + " to " + edge.getTargetNode().getName() + "." + edge.getTargetEndpoint());
+				return false;
+			}
+		}
+		return true;
+	}
+	
+	private boolean hasNoEmptyInputOutput(DirectedGraph graph,
+			Map<UUID, Class<?>> moduleClasses, StringBuilder messageBuilder){
+		List<Edge> edges = graph.getEdgeList();
+		//check the graph
 		for (int i = 0; i < graph.getNodeCount(); i++) {
 			Node node = graph.getNode(i);
 			UUID moduleId = node.getModuleId();
@@ -158,6 +241,7 @@ public class OozieEngine extends AbstractEngine {
 			ModuleEndpoint[] inputs = annotation.inputs();
 			ModuleEndpoint[] outputs = annotation.outputs();
 
+			//check empty input
 			for (ModuleEndpoint input : inputs) {
 				String inputName = input.name();
 				boolean found = false;
@@ -169,11 +253,12 @@ public class OozieEngine extends AbstractEngine {
 					}
 				}				
 				if( !found){
-					messageBuilder.append("Empty input of node " + node.getName() + " input " + inputName);
+					messageBuilder.append("<br>" + "Empty input of node " + node.getName() + " input " + inputName);
 					return false;
 				}
 			}
 			
+			//check empty output
 			for(ModuleEndpoint output : outputs){
 				String outputName = output.name();
 				boolean found = false;
diff --git a/src/main/java/haflow/engine/oozie/OozieFlowXmlGenerator.java b/src/main/java/haflow/engine/oozie/OozieFlowXmlGenerator.java
index 3290079..e620e60 100644
--- a/src/main/java/haflow/engine/oozie/OozieFlowXmlGenerator.java
+++ b/src/main/java/haflow/engine/oozie/OozieFlowXmlGenerator.java
@@ -24,11 +24,11 @@ import org.w3c.dom.Document;
 @Component
 public class OozieFlowXmlGenerator {
 	
-	public String genWorkflowXml(Flow flow, Map<UUID, Class<?>> moduleClasses, StringBuilder messageBuilder)
+	public String genWorkflowXml(Flow flow, DirectedGraph originalGraph, Map<UUID, Class<?>> moduleClasses, StringBuilder messageBuilder)
 			throws Exception {
 		messageBuilder.append("Start sorting nodes ...");
 		
-		DirectedGraph originalGraph = new DirectedGraph(flow.getNodes(), flow.getEdges());
+//		DirectedGraph originalGraph = new DirectedGraph(flow.getNodes(), flow.getEdges());
 		Map<UUID, Map<String, String>> inputConfigurations = new HashMap<UUID, Map<String, String>>();
 		DirectedGraph graph = this.graphTransformer.transform(flow, originalGraph, moduleClasses, inputConfigurations);
 		List<Integer> sorted = new TopologicalSort(graph).getOrder();
diff --git a/src/main/java/haflow/module/AbstractJavaModule.java b/src/main/java/haflow/module/AbstractJavaModule.java
index 508f6fa..416bd88 100644
--- a/src/main/java/haflow/module/AbstractJavaModule.java
+++ b/src/main/java/haflow/module/AbstractJavaModule.java
@@ -17,31 +17,15 @@ public abstract class AbstractJavaModule extends AbstractModule {
 
 		List<String> result = new ArrayList<String>();
 		for (ModuleEndpoint input : inputs) {
-			switch (input.dataType()) {
-			case PlainText:
-				String textValue = configurations.get(input.name()).trim();
-				result.add("--" + input.name());
-				result.add(textValue);
-				break;
-			case None:
-			default:
-				System.out.println("Invalid Parameters!");
-				break;
-			}
+			String textValue = configurations.get(input.name()).trim();
+			result.add("--" + input.name());
+			result.add(textValue);
 		}
 
 		for (ModuleEndpoint output : outputs) {
-			switch (output.dataType()) {
-			case PlainText:
-				String textValue = configurations.get(output.name()).trim();
-				result.add("--" + output.name());
-				result.add(textValue);
-				break;
-			case None:
-			default:
-				System.out.println("Invalid Parameters!");
-				break;
-			}
+			String textValue = configurations.get(output.name()).trim();
+			result.add("--" + output.name());
+			result.add(textValue);
 		}
 
 		for (String key : configurations.keySet()) {
diff --git a/src/main/java/haflow/module/DataType.java b/src/main/java/haflow/module/DataType.java
index 7775ee7..a0f6011 100644
--- a/src/main/java/haflow/module/DataType.java
+++ b/src/main/java/haflow/module/DataType.java
@@ -1,5 +1,35 @@
 package haflow.module;
 
 public enum DataType {
-	None, PlainText
+	PlainText, Csv, Arff, Image, Jpg, Model, ALL, AUTO;
+	
+	public static boolean matches(DataType sourceDataType, DataType targetDataType){
+		if( sourceDataType == DataType.AUTO || targetDataType == DataType.AUTO){
+			System.out.println("Error: AUTO datatype");
+			return false;
+		}
+		if( sourceDataType == targetDataType )
+			return true;
+		
+		if( contains(targetDataType, sourceDataType))
+			return true;
+
+		return false;
+	}
+	
+	private static boolean contains(DataType targetDataType, DataType sourceDataType){
+		if( targetDataType == DataType.ALL)
+			return true;
+		
+		if( targetDataType == PlainText){
+			if( sourceDataType == Csv || sourceDataType == Arff)
+				return true;
+		}
+		
+		if( targetDataType == Image){
+			if( sourceDataType == Jpg)
+				return true;
+		}
+		return false;
+	}
 }
diff --git a/src/main/java/haflow/module/data/input/AllFileInpuModule.java b/src/main/java/haflow/module/data/input/AllFileInpuModule.java
new file mode 100644
index 0000000..164a800
--- /dev/null
+++ b/src/main/java/haflow/module/data/input/AllFileInpuModule.java
@@ -0,0 +1,26 @@
+package haflow.module.data.input;
+
+import haflow.module.AbstractModule;
+import haflow.module.DataType;
+import haflow.module.Module;
+import haflow.module.ModuleConfiguration;
+import haflow.module.ModuleConfigurationType;
+import haflow.module.ModuleEndpoint;
+import haflow.module.ModuleType;
+
+import java.util.Map;
+
+@Module(id = "ada611a8-aa63-968a-ca46-4356a0e0bdab", name = "AllSourceFile", category = "Data-Source", type = ModuleType.SOURCE, 
+	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
+	inputs = { }, 
+	outputs = { @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.ALL)})
+public class AllFileInpuModule extends AbstractModule {
+
+	@Override
+	public boolean validate(Map<String, String> configurations,
+			Map<String, String> inputs, Map<String, String> outputs) {
+		// TODO Auto-generated method stub
+		return false;
+	}
+
+}
diff --git a/src/main/java/haflow/module/datamining/ArffFileModule.java b/src/main/java/haflow/module/data/input/ArffFileInpuModule.java
similarity index 77%
rename from src/main/java/haflow/module/datamining/ArffFileModule.java
rename to src/main/java/haflow/module/data/input/ArffFileInpuModule.java
index 1eeb65f..1e1fee3 100644
--- a/src/main/java/haflow/module/datamining/ArffFileModule.java
+++ b/src/main/java/haflow/module/data/input/ArffFileInpuModule.java
@@ -1,4 +1,4 @@
-package haflow.module.datamining;
+package haflow.module.data.input;
 
 import haflow.module.AbstractModule;
 import haflow.module.DataType;
@@ -10,11 +10,11 @@ import haflow.module.ModuleType;
 
 import java.util.Map;
 
-@Module(id = "ada611a8-aa63-968a-ca46-4356a0e0bdab", name = "ArffSourceFile", category = "Data-Source", type = ModuleType.SOURCE, 
+@Module(id = "ada611a8-aa63-968a-1146-4356a0e0bdab", name = "ArffSourceFile", category = "Data-Source", type = ModuleType.SOURCE, 
 	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
 	inputs = { }, 
-	outputs = { @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.PlainText)})
-public class ArffFileModule extends AbstractModule {
+	outputs = { @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.Arff)})
+public class ArffFileInpuModule extends AbstractModule {
 
 	@Override
 	public boolean validate(Map<String, String> configurations,
@@ -23,5 +23,4 @@ public class ArffFileModule extends AbstractModule {
 		return false;
 	}
 
-
 }
diff --git a/src/main/java/haflow/module/data/input/PlainTextInputFileModule.java b/src/main/java/haflow/module/data/input/PlainTextInputFileModule.java
new file mode 100644
index 0000000..45fed32
--- /dev/null
+++ b/src/main/java/haflow/module/data/input/PlainTextInputFileModule.java
@@ -0,0 +1,26 @@
+package haflow.module.data.input;
+
+import haflow.module.AbstractModule;
+import haflow.module.DataType;
+import haflow.module.Module;
+import haflow.module.ModuleConfiguration;
+import haflow.module.ModuleConfigurationType;
+import haflow.module.ModuleEndpoint;
+import haflow.module.ModuleType;
+
+import java.util.Map;
+
+@Module(id = "34a611a8-aa63-968a-ca46-4356a0e0bdab", name = "TextSourceFile", category = "Data-Source", type = ModuleType.SOURCE, 
+	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
+	inputs = { }, 
+	outputs = { @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.PlainText)})
+public class PlainTextInputFileModule extends AbstractModule {
+
+	@Override
+	public boolean validate(Map<String, String> configurations,
+			Map<String, String> inputs, Map<String, String> outputs) {
+		// TODO Auto-generated method stub
+		return false;
+	}
+
+}
diff --git a/src/main/java/haflow/module/data/output/AllOutputFileModule.java b/src/main/java/haflow/module/data/output/AllOutputFileModule.java
new file mode 100644
index 0000000..fa2274f
--- /dev/null
+++ b/src/main/java/haflow/module/data/output/AllOutputFileModule.java
@@ -0,0 +1,26 @@
+package haflow.module.data.output;
+
+import java.util.Map;
+
+import haflow.module.AbstractModule;
+import haflow.module.DataType;
+import haflow.module.Module;
+import haflow.module.ModuleConfiguration;
+import haflow.module.ModuleConfigurationType;
+import haflow.module.ModuleEndpoint;
+import haflow.module.ModuleType;
+
+@Module(id = "12a611a8-aa63-118a-ca46-4356a0e0bdab", name = "AllTargetFile", category = "Data-Target", type = ModuleType.DEST, 
+	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
+	inputs = {  @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.ALL) }, 
+	outputs = {})
+public class AllOutputFileModule extends AbstractModule {
+
+	@Override
+	public boolean validate(Map<String, String> configurations,
+			Map<String, String> inputs, Map<String, String> outputs) {
+		// TODO Auto-generated method stub
+		return false;
+	}
+
+}
diff --git a/src/main/java/haflow/module/data/output/ArffOutputFileModule.java b/src/main/java/haflow/module/data/output/ArffOutputFileModule.java
new file mode 100644
index 0000000..75044ec
--- /dev/null
+++ b/src/main/java/haflow/module/data/output/ArffOutputFileModule.java
@@ -0,0 +1,26 @@
+package haflow.module.data.output;
+
+import java.util.Map;
+
+import haflow.module.AbstractModule;
+import haflow.module.DataType;
+import haflow.module.Module;
+import haflow.module.ModuleConfiguration;
+import haflow.module.ModuleConfigurationType;
+import haflow.module.ModuleEndpoint;
+import haflow.module.ModuleType;
+
+@Module(id = "21a611a8-aa63-118a-ca46-4356a0e0bdab", name = "ArffTargetFile", category = "Data-Target", type = ModuleType.DEST, 
+	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
+	inputs = {  @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.Arff) }, 
+	outputs = {})
+public class ArffOutputFileModule extends AbstractModule {
+
+	@Override
+	public boolean validate(Map<String, String> configurations,
+			Map<String, String> inputs, Map<String, String> outputs) {
+		// TODO Auto-generated method stub
+		return false;
+	}
+
+}
diff --git a/src/main/java/haflow/module/datamining/TxtOutputModule.java b/src/main/java/haflow/module/data/output/PlainTextFileOutputModule.java
similarity index 74%
rename from src/main/java/haflow/module/datamining/TxtOutputModule.java
rename to src/main/java/haflow/module/data/output/PlainTextFileOutputModule.java
index e84b10b..a073fc6 100644
--- a/src/main/java/haflow/module/datamining/TxtOutputModule.java
+++ b/src/main/java/haflow/module/data/output/PlainTextFileOutputModule.java
@@ -1,4 +1,4 @@
-package haflow.module.datamining;
+package haflow.module.data.output;
 
 import java.util.Map;
 
@@ -10,11 +10,11 @@ import haflow.module.ModuleConfigurationType;
 import haflow.module.ModuleEndpoint;
 import haflow.module.ModuleType;
 
-@Module(id = "ada611a8-aa63-118a-ca46-4356a0e0bdab", name = "TextDestFile", category = "Data-Source", type = ModuleType.DEST, 
+@Module(id = "ada611a8-aa63-118a-ca46-4356a0e1cdab", name = "TextTargetFile", category = "Data-Target", type = ModuleType.DEST, 
 	configurations = { @ModuleConfiguration(key = "path", displayName = "path: Data path", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT)}, 
 	inputs = {  @ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.PlainText) }, 
 	outputs = {})
-public class TxtOutputModule extends AbstractModule {
+public class PlainTextFileOutputModule extends AbstractModule {
 
 	@Override
 	public boolean validate(Map<String, String> configurations,
diff --git a/src/main/java/haflow/module/datamining/DescribeModule.java b/src/main/java/haflow/module/datamining/DescribeModule.java
index c69c2ca..bbec01f 100644
--- a/src/main/java/haflow/module/datamining/DescribeModule.java
+++ b/src/main/java/haflow/module/datamining/DescribeModule.java
@@ -15,7 +15,7 @@ import java.util.Map;
 		@ModuleConfiguration(key = "descriptor", displayName = "descriptor: Data descriptor", pattern = "^(.*)$", type = ModuleConfigurationType.PLAIN_TEXT),
 		@ModuleConfiguration(key = "regression", displayName = "regression: Regression Problem", pattern = "^(.*)$", type = ModuleConfigurationType.BOOLEAN) }, 
 	inputs = { 
-		@ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.PlainText) }, 
+		@ModuleEndpoint(name = "path", minNumber = 1, maxNumber = 1, dataType = DataType.Arff) }, 
 	outputs = {
 		@ModuleEndpoint(name = "file", minNumber = 1, maxNumber = 1, dataType = DataType.PlainText) })
 public class DescribeModule extends AbstractJavaModule {