Request for help with XML issues

I have ran into several issues with regards to the W3C XML Schema and was hoping someone could giv e some help with them.

The main issue is whether XML Schema validation is possible with XLink? I am currently using JAXB to validate XML documents against their schema but have come a little stuck when trying to incorporate XLink.

Also, during validation, is it possible for XML Schema default values (both for elements and attributes) to be set during validation of a document instance and if these can be accessed after unmashalling?

I will fully appreciate any help and advice anyone can give on these topics and will await eagerly for a reply.

Gautam