Also, the packages javax.xml.stream, javax.xml.stream.events and javax.xml.stream.util were added to support StAX. In addition, the class Validator have also to accept StAXSource.
For me, to add StAX support, it would be just implement the interfaces provided by these packages and plug them into the existent code. For example, in the org.apache.xalan.processor.TransformerFactoryImpl's method newTemplates(Source source), I would add a condition to test if the source is a StAX one and then create the correct TemplatesHandler instance, that will create the Templates object.
I don't know exactly how prepared is Xalan to receive these changes.
I need help to understand the project's structure. Then I will be able to do the work of the 2 next weeks (as provided in the plan): define precisely the changes I will do.