METS Java Toolkit / The JAXB Framework
Draft Version 1.0 (alpha) 2002/03/15

In creating an API for the METS toolkit we had two options:

1. Define a new API
2. Use an existing API specification

The JAXB product is comprised of a set of base classes (the javax.xml.bind package); a schema-driven compiler for generating schema-specific binding classes, which are sub-classed from the JAXB base classes; and a set of run-time marshalling classes (the javax.xml.marshal package) invokable by the derived binding classes. JAXB provides mechanisms for local and global type and structural validation, and for marshalling to and from binding class instatiations and XML instance documents.

The organization of JAXB is presented graphically in the following figure:

The JAXB specification is still in early pre-release development. Although a preliminary early version implementation of the class generator has been released, it only accepts as input a subset of the XML DTD language; XML schema is not supported at all. Thus, all of the base classes as well as the METS schema-specific class used in the toolkit were constructed manually, following the JAXB API specification.

Note: Sun has announced that the future production release of the JAXB specification may be incompatible with the current pre-release version. The question of whether to stay with the current format of the METS toolkit or whether to migrate it into compliance with subsequent JAXB specification at some future time remains under discussion.