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IncompatibleClassChangeError when deploying Axis 1.2-RC3 on WebSphere 5.1 with PARENT_FIRST classloading

I am deploying Axis 1.2RC3 in a war that resides within an ear. The axis jars are in the war/WEB-INF/lib dir. For various reasons related to the other contents of my ear, I must use PARENT_FIRST classloading. As many have reported, if you have PARENT_FIRST classloading on WebSphere 5.1 with Axis 1.2RC3, then there is a conflict between the version of saaj (1.1) that ships with WebSphere, and the version of saaj (1.2) that Axis 1.2RC3 expects, and you get the following exception:

java.lang.IncompatibleClassChangeError: class org.apache.axis.SOAPPart does not implement interface org.w3c.dom.Document

This issue can be resolved with PARENT_LAST classloading and a manifest which specifies the classpath…but for those of use who can’t use PARENT_LAST classloading, there is another option.

It appears that a single source code change to Axis will eliminate the issue altogether. The offending code is in org.apache.axis.message.MessageElement.addTextNode(), and can be patched as follows:

OLD CODE:

public SOAPElement addTextNode(String s) throws SOAPException {
    try {
            Text text = getOwnerDocument().createTextNode(s);
            ((org.apache.axis.message.Text)text).setParentElement(this);
            return this;
        } catch (ClassCastException e) {
           throw new SOAPException(e);
        }
}

PATCHED CODE:

public SOAPElement addTextNode(String s) throws SOAPException {
    try {
            Text text = new org.apache.axis.message.Text(s);
            this.appendChild(text);
            return this;
        } catch (ClassCastException e) {
            throw new SOAPException(e);
}

After making this change, Axis 1.2RC3 will run on WebSphere 5.1 with PARENT_FIRST classloading, and no exceptions will be thrown.

That’s it. Hope this helps.

Tags: Axis, hacking, WebSphere