RelaxNg

Last edit November 24, 2004

RELAX NG (REgular LAnguage description for XML Next Generation).

The "next generation" part was the work of OasisOrganization.

RelaxNg has been adopted by ISO as a standard for DSDL (Document Schema Definition Language). See earlier draft at http://www.y12.doe.gov/sgml/sc34/document/0362_files/relaxng-is.pdf

Note there is a "compact syntax" version but it is not an ISO standard. The notation is non XML, but can be converted to RelaxNg without information loss.
There was a concern registered about the acceptability of RelaxNg in a government environment. That was before the ISO adoption and I am unsure what is the situation and outlook at end 2004.

From the charter at http://www.oasis-open.org/committees/relax-ng/ :

The purpose of this committee is to create a specification for a schema language for the ExtensibleMarkupLanguage based on TREX and RELAX. The key features of RELAX NG are that it is simple, easy to learn, uses XML syntax, does not change the information set of an XML document, supports XML namespaces, treats attributes uniformly with elements so far as possible, has unrestricted support for unordered content, has unrestricted support for mixed content, has a solid theoretical basis, and can partner with a separate datatyping language (such W3C XmlSchema Datatypes).

-- AndrewJoyner

Links for RelaxNg ancestors:

RELAX at http://www.xml.gr.jp/relax/faq-e.html
TREX (Tree Regular Expression for XML) at http://www.service-architecture.com/xml/articles/tree_regular_expression_for_xml_trex.html

RelaxNg is reported in XmlEurope2004 to have superseded XmlSchema in market adoption due to its simplicity over the latter. (see http://www.xml.com/pub/a/2004/04/21/state.html)

Resources

Relax NG tutorial from Oasis http://www.oasis-open.org/committees/relax-ng/tutorial.html

Technology report from Oasis http://xml.coverpages.org/relax-ng.html

Compact Syntax tutorial http://relaxng.org/compact-tutorial-20030326.html

A simpler schema Language for XML http://personalweb.about.com/b/a/2004_01_16.htm

RelaxNg online book http://books.xmlschemata.org/relaxng/page2.html

Comparison with XmlSchema http://webreference.com/xml/column59/

More comparisons, with code examples http://www.xml.com/lpt/a/2002/01/23/relaxng.html

Free Xml tools http://www.garshol.priv.no/download/xmltools/std_ix.html#S_RELAX-NG

Schema tutorial XmlSchema and RelaxNg http://www.zvon.org/xxl/XMLSchemaTutorial/Output/series.html

RelaxNg QuickQuestions

Q What is the extent of support of RelaxNg by tools as at end 2004? Are there free and commonly used tools available for the MicrosoftWindows environment before DotNet came out?

A see http://gnosis.cx/publish/programming/xml_matters_26.html for editors (e.g. XML Operator) and converters (e.g. trang & DTDinst)

Q What is RELAX, and what is the NG in the RelaxNg stand for? And why should someone who need to do a bit of Xml care about RelaxNg?

A RELAX NG (pronounced "relaxing") is a grammar-based schema language. The NG stands for New Generation. See ISBN 0596004214