Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/ToolContentVersionFilter.java
===================================================================
diff -u
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/ToolContentVersionFilter.java	(revision 0)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/ToolContentVersionFilter.java	(revision e6467356d40fb0b6402bde8a6700e633167c3693)
@@ -0,0 +1,112 @@
+package org.lamsfoundation.lams.learningdesign.service;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang.StringUtils;
+import org.jdom.Document;
+import org.jdom.Element;
+import org.jdom.JDOMException;
+import org.jdom.input.SAXBuilder;
+import org.jdom.output.XMLOutputter;
+
+import com.thoughtworks.xstream.XStream;
+
+public class ToolContentVersionFilter {
+
+	private List<RemovedField> removedFieldList;
+	private List<AddedField> addedFieldList;
+
+	public ToolContentVersionFilter(){
+		removedFieldList = new ArrayList<RemovedField>();
+		addedFieldList = new ArrayList<AddedField>();
+	}
+	//container class for removed class
+	class RemovedField{
+		public Class ownerClass;
+		public String fieldname;
+		public RemovedField(Class ownerClass, String fieldname) {
+			this.ownerClass = ownerClass;
+			this.fieldname = fieldname;
+		}
+	}
+//	container class for added class
+	class AddedField{
+		public Class ownerClass;
+		public String fieldname;
+		public Object defaultValue;
+		public AddedField(Class ownerClass2, String fieldname2, Object defaultValue2) {
+			this.ownerClass = ownerClass2;
+			this.fieldname = fieldname2;
+			this.defaultValue = defaultValue2;
+		}
+		
+	}
+	public void removeField(Class ownerClass, String fieldname){
+		removedFieldList.add(new RemovedField(ownerClass,fieldname));
+	}
+	
+	public void addField(Class ownerClass, String fieldname, Object defaultValue){
+		addedFieldList.add(new AddedField(ownerClass, fieldname, defaultValue));
+	}
+
+	public void transformXML(String toolFilePath) throws JDOMException, IOException{
+		File toolFile = new File(toolFilePath);
+		
+		SAXBuilder sax = new SAXBuilder();
+		Document doc = sax.build(new FileInputStream(toolFile));
+		Element root = doc.getRootElement();
+		retrieveXML(root);
+		
+		toolFile.renameTo(new File(toolFilePath +"_oldver"));
+		
+		File newToolFile = new File(toolFilePath);
+		XMLOutputter output = new XMLOutputter();
+		output.output(doc, new FileOutputStream(newToolFile));
+	}
+	
+	private void retrieveXML(Element root) throws JDOMException{
+		//collect all removed fields in this class
+		List<String> clzRemoveFlds = new ArrayList<String>();
+		for (RemovedField remove : removedFieldList) {
+			if(StringUtils.equals(root.getName(),remove.ownerClass.getName())){
+				clzRemoveFlds.add(remove.fieldname);
+			}
+		}
+		//add all new fields for this class
+		for (AddedField added : addedFieldList) {
+			if(StringUtils.equals(root.getName(),added.ownerClass.getName())){
+				Writer eleWriter = new StringWriter();
+				XStream eleX = new XStream();
+				eleX.toXML(added.defaultValue,eleWriter);
+				
+				SAXBuilder eleBuilder = new SAXBuilder();
+				Document eledoc = eleBuilder.build(new StringReader(eleWriter.toString()));
+				Element eleRoot = eledoc.getRootElement();
+				eleRoot.setName(added.fieldname);
+				root.addContent(eleRoot);
+			}
+		}
+		
+		List<Object> children = root.getChildren();
+		for (Object child: children) {
+			if(child instanceof Element){
+				Element ele = (Element)child;
+				if(clzRemoveFlds.contains(ele.getName())){
+					continue;
+				}
+				retrieveXML(ele);
+			}
+		}
+		for(String name:clzRemoveFlds)
+			root.removeChild(name);
+
+	}
+}