Java API for XML Processing.
A standard part of Java 1.4:
javax.xml.parsers - bootstrapping and using XML processors.
javax.xml.transform - APIs for transforming documents (e.g. XSLT)
javax.xml.transform.dom - DOM APIs related to transformations.
javax.xml.transform.sax - SAX APIs related to transformations.
javax.xml.transform.stream - I/O stream APIs related to transformations.
API Documentation: Java Standard Edition 1.4