TREX - a new schema language

Date:      Mon, 08 Jan 2001 19:09:41 +0700
From:      James Clark <jjc@jclark.com>
To:        XML Developers' List <xml-dev@lists.xml.org>
Subject:   TREX - a new schema language

I've designed and implemented a small, simple schema language. It's called TREX (Tree Regular Expressions for XML). Calling it a schema language is perhaps misleading: its goal is purely validation. It doesn't aim to assist in interpreting or processing the document. The post-validation infoset is exactly the same as the pre-validation infoset.

You can find more, including a tutorial, a (relatively) formal spec and a sample implementation in Java on top of SAX2 at:

http://www.thaiopensource.com/trex/.

It's basically the type system of XDuce with an XML syntax and with a bunch of additional features (like support for attributes and namespaces) needed to make it a practical language for structure validation. Of existing Schema languages, it's closest to RELAX. It's not tied to any particular datatyping language; rather, the idea is that you can plug whatever datatyping language you want (e.g., XML Schemas Part 2).

This is the first release, so there will certainly be bugs in both the documents and the implementation.

I plan to continue to refine both the design and the implementation. Input is welcome.

James

Prepared by Robin Cover for The XML Cover Pages archive. See: "Tree Regular Expressions for XML (TREX)."

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