Library file for style task

[Sivaprasad . Kancherla]

I am trying to execute a style task and get the following error.

java.lang.NoClassDefFoundError: javax/xml/transform/Source
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:124)
        at
org.apache.tools.ant.taskdefs.XSLTProcess.setProcessor(XSLTProcess.java:229)
.
.

I tried including xalan.jar, crimson.jar and xerces.jar into the classpath
in vain. None of them contain javax.xml.transform package.

Where do I find the jar file needed for style task?

-Siva