Multi-tier Migration

Continue with version "0" of the Task class defined in Getting Started chapter:

package example;

public class Task {
        public boolean prioritized;
}

Now we have class CompileTask subclassing from Task class as below:

package example;

import java.util.List;

public class CompileTask extends Task {
        public List<String> srcFiles;
}

Instance of CompileTask can be serialized to XML with XMT as below:

package example;

import java.util.ArrayList;

import com.pmease.commons.xmt.VersionedDocument;

public class Test {
	public static void main(String args[]) {
		CompileTask task = new CompileTask();
		task.prioritized = true;
		task.srcFiles = new ArrayList<String>();
		task.srcFiles.add("Class1.java");
		task.srcFiles.add("Class2.java");
		String xml =VersionedDocument.fromBean(task).toXML();
                writeXMLToFileOrDatabase(xml);
	}
}

The resulting XML will be:

<?xml version="1.0" encoding="UTF-8"?>

<example.CompileTask version="0.0">
  <prioritized>true</prioritized>
  <srcFiles>
    <string>Class1.java</string>
    <string>Class2.java</string>
  </srcFiles>
</example.CompileTask>

Pay attention to version attribute of the root element: XMT examines the class hierarchy (except for class java.lang.Object) to get current version of each class, and concatenates them with period. Since there are no migrate methods defined in class Task and CompileTask, current version of both classes are of "0", so the resulting version of the hierarchy will be "0.0".

Multi-tier Migration

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