The Schematron

An XML Structure Validation Language using
Patterns in Trees

(If you have have news about Schematron or similar schema languages, please email Rick Jelliffe ricko (at) topologi.com

News 2006

News 2005

• Minor editorial corrections to ISO Schematron Committe Draft available at SCHEMATRON.COM
• Schematron 1.5 validation available in new Topologi Judge validation utility and Topologi Markup Editor 2.4 editor

January

• Schematron 1.5 validation support added to Oxygen XML editor

News 2004

• The final committee draft of ISO Schematron is now available at SCHEMATRON.COM, a website set up to provide material concerning the International Standard Schematron.
• Daniel Cazzulino to speak All about Schematron at Applied XML Developer's Conference (DEVCON) October
• Rick Jelliffe to give keynote Method and Opportunity at XML Open 2004, Cambridge University, UK, September
• The Committee Draft of ISO Schematron is available here in PDF. For an ASCII version, here is Google's transcription. The draft International Standard, with several improvements, is expected to be prepared and available in October 2004. The editor, Rick Jelliffe, would like to express his appreciation for the Open Source implementers who have used the drafts to implement Schematron and provide feedback, and to the reviewers from the international standards bodies for their careful scrutinization.
• Scimitar is a Python implementation of draft ISO Schematron
• For .NET users, Schematron.NET is an open source implementation at Source Forge.
• IBM have added Schematron to their Alphaworks technology Business Integration Information Conformance Statements.
• The JAXEN XPath engine for Java may be optimized for better Schematron performance.
• A JUnit-related open source project Schema Unit Test allows Schematron schemas.
• Open GIS (Geographical Information Systems) has added Schematron as a constraint language to their Geography Markup Language.
• Topologi Professional Edition is an analytics and reporting tool, including editor, that allows Schematron validation of XML and SGML documents. Multiple documents can be validated in batch. Document sets can be sampled, and a Schematron "usage schema" generated, to allow testing that new documents have the same structure as previous documents. Schematron validation is also possible from the context-sensitive tree editor, and the markup editor.
• Microsoft mulling putting Schematron into Longhorn: why not?

News 2003

• Article An Introduction to Schematron by Eddie Robertsson, who implemented the widely used free Schematron/DTD/RELAX NG/WXS validator from Topologi.
• XML Journal publishesulti-part article from XML Spy people on how to integrate XMl Spy and Schematron.
• WebMethods adds proprietary XPath assertions to API, and reference Schematron in MSDN article as the standard manner.
• Jing is a high-quality validation library from the famous James Clark, who was the technical lead on XML, editor of the Xpath and ISO DSSL specifications, co-inventor of the RELAX NG schema language, and developer of some of the most popular Open Source softtware libraries: sgmls, nsgmls (SP), xt, xp, jade. This library provides support for RELAX NG (compact and full syntaxes), Schematron, WXS datatypes, NRL adn even WXS (through Xerces).

May

• Topologi announced Validating Proxy, which allows Schematron and WXS valdiation of incoming data to Web Services or web services.
• Rick Jelliffe announces beta versions of Schematron 1.6 implementation. The software is a new skeleton, a new preprocessor (before the skeleton), and a new http://www.topologi.com/resources/tmp/schematron-report-portable1-6.xsl"> report tool.

News 2002

• Schematron.Net is an open source, high-performance implementation of Schematron for the .NET platform by Daniel Cazzulino. This implementation is interesting because it does not use XSLT but C#. Daniel reports that it seems to be about 50% faster than the fastest XSLT engines.
• Topologi Collaborative Markup Editor version 1.0 released, with free evaluation downloads. The editor supports Schematron validation and phases, as well as embedded Schematron in RELAX NG and W3C XML Schema. From a validation POV it it also interesting because it supports "feasible" validation (of DTDs and RELAX NG schemas).

August

• Schematron scores better than any other schema language: results of study by respected authorities! XML 2001 Schema Language Comparison Town Hall
• Revised Schematron 1.5 specification corrects errors, provides roadmap for ISO Schematron.

June

• Topologi Schematron Validator updated, adding RELAX NG schemas and Schematron-embedded-in-RELAX NG.
• Eddie Robertsson announces XSLT tools for Embedded Schematron in Relax along similar lines to Embedded Schematron in W3C XML Schemas and explained in an article.

May

• Implementation of Schematron available for PHP at http://phpxmlclasses.sourceforge.net/
• Schematron moves closer to ISO standardization. See article on DSDL at www.dsdl.org/ and also another article
• Article Filling in the Gaps with Schematron on XML.COM by Bob DuCharme on Schematron.
• Schematron featured in three papers at XML Europe 2002 Conference in Barcelona: a comparison of Schematron and XCSL, a disussion on progressive validation, and a discussion on Schema Languages.

Before May

• Schematron used in Apache Cocoon project for validating XML forms. This is a Java implementation rather than using XSLT, and is retported to have excellent performance.
• Schematron-in-Relax supported added to Sun's Multi Schema Validator.

(Due shifts in countries and jobs, I was not able to maintain this list for about a year. I apologise for this, especially for people who had news - Rick Jelliffe)

News 2001

• XML Content Management System Using XSLT, Schematron, and Ant by Eric van der Vlist, Conference paper at O'Reilly Open Source Convention, XTech 2001: Cutting Edge XML.

June

• Release of Topologi Schematron Validator, a free Windows GUI-based tool for running Schematron validations over multiple files. Also supports DTDs and W3C XML Schema. Highly configurable, to allow experimentation and development of schemas.
• Part fo the same release is updated version of most of the publically-available Schematron schemas, and improved versions of the 1.5 implementation. These will be placed on the Schematron 1.5 website shortly.

May

• XML Schemas Best Practices (compiler: R. Costello) includes section on embedding Schematron into XML Schemas appinfo elements.
• Commerical product supporting Schematron: FourThought Inc's 4Suite Server allows Schematron validation (sorry, I missed announcing this at the right time.)
• This is again undated, byt nice to see Schematron correctly listed under "programming by contract" at Java Repository
• Rick Jelliffe speaks at XSE 01, the XML Software Engineering Workshop connected with the big ACM Software Engineering conference in Toronto. Subject: Schematron versus XML Schemas. Trip sponsored by Zuelke Engineering of Swizterland. Workshop program committee also includes Grady Booch, showing the growing interest in XML. (Paper to be put on line soon.)

April

• Schematron Java API from Anna Hovhannisian, Oliver Becker
• Schematron: validating XML using XSLT by Leigh Dodds, Conference paper from XSLT-UK Conference. Also at Dodd's site.
• Types and Data Formats: DTDs, Schema, Schematron by Alexander Nakhimovsky. Flier for conference paper at XML Devcon Spring 2001.

March

• Examplotron
• WSDL page by Simon Fell includes WSDL Schema in Schematron
• Schemas by Elliotte Rusty Harold, Conference paper from XMLOne London (but note I think the second assert in the song example should be something like *[position()=1][self::TITLE].)
• XML Schemas Training Course by Allette Systems includes Schematron material
• Eddie Robertsson's XSD_Schtrn is a stylesheet for extracting schematron schema fragments embedded as appinfo in XML Schemas <;appinfo> elements beta.
• Miloslav Nic's zvonSchematron is an implementation of Schematron 1.5 and is accompanied by a nice test reporting system, see Text Output. beta

February

• Schematron under consideration for project to create A Simple Collaboration System which is directly inspired by Doug Englebart's ideas. Very interesting. K. Holman put them onto Schematron, it seems. Very interesting to see where this goes.
• Schemarama
• XML Schemas, by Brad Perry, Course notes including good Schematron overview. Note also an assignment comparing DTD, XML Schemas and Schematron. Nice.
• Small note on Logical Inferences from Schematron Schemas by Rick
• skeleton1-5.xsl reference implementation page, featuring links to conformance report, basic API documentation, sample code and sample .BAT file. schematron-report, schematron-message and schematron-basic moved over from 1.3. and documentation updated.
• Good summary of exchanges on XML-DEV comparing rule-based and grammar-based schema approaches at XML.COM
• The Screamatron Torture Test are the results so far of Rick's attempts to get Schematron going on 12 different command-line XSLT implementations for Windows, and to make the code inoffensive. Result: MSXSL (MSXML3), SAXON and Oracle work fine. XT, Xalan, and Sablotron can work with certain caveats. (Note: this is not an exhaustive test of all XSLT or Schematron features, nor of all XSLT implementations. For example, FourThought's Python-based implementation, which is reported to work, has not been tested yet.)
• Start at API documentation for extending the skeleton1-5.xsl
• Testing continues with Unicorn (no), Xalan for C 1 (yes with workaround), Xalan for Java 2 (yes, with workaround).
• Alternative validation language idea Hook may interest some people

January

• Complete beta implementation of Schematron 1.5 by Rick Jelliffe and collaborators (merging code from existing implementations) available now.
  • Same version works with both namespace and non-namespace
  • Implements phases, diagnostics, inherited abstract rules, value-of.
  • Command-line options to select the active phase or turn off diagnostics.
  • Better compile-time error messages.
  • Uses Oliver Becker's architecture, so should be compatible with existing 1.3 meta-stylesheets.
  • Extends the architecture to make available more attributes.
  • Uses conservative subset of XSLT so is still compatible with XP (providing key() is not used in schema). Also tested on SAXON, Instant SAXON and Sablotron (OK but does not support import yet, so metastylesheets have to be merged by hand.) See Implementation Notes for diary of some issues.
  The Schematron 1.5 Schema for Schematron 1.5 has been upgraded to use diagnostics, phases and an abstract element to demonstrate the usage of these. Existing 1.3 Schematron schemas should be compatible with the new 1.5. This is a beta, please report any problems and suggested fixes/enhancements.
• Accompanying this is an implementation of the conformance language. This is a meta-stylesheet for the skeleton, and is also a good example of how to use the skeleton. The conformance language is used to check whether an implementation works correctly on different versions of XSLT.
• Schematron 1.5 manual updated.
• Conformance Language for Schematron 1.5 implementations draft available now
• Schematron 1.5 beta now being tested with XT, SAXON, Instant SAXON and Sablotron. Due for this week.
• New page design for home page at Academia Sinica (i.e. what you are reading now) with rewrite.
• Namespace URI for Schematron now locates a RDDL Resource Directory.
• New DTD, W3C XML Schema schema and Schematron schema for Schematron 1.5.

For old news, see the old home page.

Overview

The Schematron can be useful in conjunction with many grammar-based structure-validation languages: DTDs, XML Schemas, RELAX, TREX, etc. You can even embed a Schematron schema inside an XML Schema <appinfo> element!

Schematron's Six Basic Elements

<schema xmlns="http://www.ascc.net/xml/schematron">
  <title>A Schematron Mini-Schema for Schematron</title>
  <ns prefix="sch" uri="http://www.ascc.net/xml/schematron">
  <pattern>
    <rule context="sch:schema">
      <assert test="sch:pattern"
      >A schema contains patterns.</assert>
      <assert test="sch:pattern/sch:rule[@context]"
      >A pattern is composed of rules.
      These rules should have context attributes.</assert>
      <assert test="sch:pattern/sch:rule/sch:assert[@test] or sch:pattern/sch:rule/sch:report[@test]"
      >A rule is composed of assert and report statements. 
      These rules should have a test attribute.</assert> 
    </rule>
  </pattern>
</schema>

Copyright 1999-2001 (C) Rick Jelliffe, Academia Sinica Computing Centre, Taibei. The Schematron software and this page are available for any public use, under the conditions of the zlib/libpng license (the least restrictive), but please mention our names in any documentation or About screens for any products that uses it. Comments, fixes and upgrades welcome: email ricko@gate.sinica.edu.tw