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Schematron is an ISO/IEC Standard.
  • ISO/IEC 19757-3:2006 Information technology -- Document Schema Definition Language (DSDL) -- Part 3: Rule-based validation -- Schematron
  • Available free at the ISO website
  • Royalty-free
  • Next version due 1Q2011!
Mature public implementation
  • Available free here at Schematron.com
  • Open Source (OSI compliant zlib/libpng license or Apache License)
  • Available for XSLT1 and XSLT2
  • Trivially runnable in Java, .NET, C++, Bat files, XProc, etc. Ant task available.
  • In continuous development since 1999.
  • Extend with API or use XML output
  • Tracks the ISO standard.
  • Localized to Czech, Dutch, English, French and German.
Much tutorial material on the WWW
Uses by Government and International Agencies Adoption
Uses by Government and International Agencies (Europe)
Uses by Industry and Consortia
Used to enforce Naming and Design Rules or Methodologies
Community
  • The Schematron-Love-In mail list is a mail list dedicated to Schematron, hosted courtesy of eec.net. UPDATE: This list seems to be available again, after a period of dormancy in 2009, and its archives are available.
  • In the early 2000s, a different Schematron-Love-In mail list was hosted at sourceforge.net. This list is now closed due to spam but archives may be available. (Update: it seems to be accepting posts but should not be used.)
  • Most Schematron questions relate to XPath. The XSLT list at Mulberry is an excellent source of expertise.
  • Another source of expertise is the XML-DEV mail list.
  • For comments relating to the standard, use the dsdl-comment mail list at dsdl.org
  • NIEMatron is a blog for discussing Schematron and NIEM.
  • Rick Jelliffe's blog on O'Reilly.com often has Schematron-related articles.
Commercial Training


Software

Under the Hood

The 'Skeleton' implementation of ISO Schematron at Schematron.com is a four-stage XSLT pipeline. The first two stages are macro-processors and only necessary if expert features are being used.

The basic processing now looks like this, as a shell script or BAT file:

 xslt -stylesheet iso_dsdl_include.xsl  theSchema.sch > theSchema1.sch
 xslt -stylesheet iso_abstract_expand.xsl  theSchema1.sch > theSchema2.sch
 xslt -stylesheet iso_svrl_for_xsltn.xsl  theSchema2.sch > theSchema.xsl
 xslt -stylesheet theSchema.xsl  myDocument.xml > myResult.xml

Schematron Skeleton

2010-04-21 - Include preprocessor now reports some common XPath errors at compile time

2010-04-15 - Distibution now includes Dutch and Czech localization. Distribution now includes ISO Schematron versions of Eddie Robertsson's stylesheets for extracting embedded Schematron patterns from XSD and RELAX NG schemas.

Updated version of Schematron for Ant released (Java JAR file, beta). This allows ISO Schematron and Schematron 1.5 validation from an ANT task, with many options available.

2010-04-14 - The ISO Schematron here is now available as two distributions:

The distributions feature the new pipeline arrangement: Schematron validation now takes four XSLT stages, but they are all similar. 1) Process inclusions. 2) Process abstract patterns. 3) Compile the schema. 4) Validate.

I am moving to this distribution system, in order to make life easier for downloaders to figure out what is needed.

It includes full support for ISO Schematron including abstract patterns, as well as support for community-requested features on trial for the the updated standard, in particular XSLT2 support.

Enhancements in this version include features for smarter SVRL output, and parameters for better internationalization, and better integration with toolchains. As well there is better support for XSLT2 and the preprocessors to provide full support of ISO Schematron. (I believe it is a 100% coverage of the ISO standard now, but it also allows various experimental and requested extensions to gain experience for an updated version of the ISO Standard.)

Experimental: let expressions can contain element content directly as an alternative to the value attribute. This is more like XSLT, and allows factoring out of systematic data into lists: previously this could only be done by having an external document, which is overkill and cumbersome sometimes.

Please send comments and fixes. Implementers of metastylesheets should note that the skeleton API signatures have slightly changed: in particular, to support properties on rule, assert and report elements. Other metastylesheets are available elsewhere on this site. If you want to make your own meta-stylesheet or adapt one here, see this documentation.

2009-05-18 - minor fix of XSLT2 version needed for a certain XSLT engine (tunnel)

2009-02-19 - release

2009-02-25 - update to resolve XSLT1 variable scope issue

2009-03-18 - update for minor fix, + fr and de translations




Comments Solicited!

The Committee Draft (PDF) of the next version of the ISO standard for Schematron is now available to the public. Please comment!

FAQ

What is Schematron?

A language for making assertions about the presence or absence of patterns in XML documents. See this overview for more information.

What is Schematron used for?

Business rules validation, data reporting, general validation, quality control, quality assurance, firewalling, constraint checking, naming and design rules checking, statistical consistency, data exploration

Who uses Schematron?

Schematron is an ISO standard which has uptake in many industries, notably the financial sector (especially insurance), governmental record exchange, and technical and reference publishing.

Is Schematron a replacement for XSD?

While Schematron can express the same constraints that can be expressed in grammar-based schema languages such as XSD (W3C XML Schemas), RELAX NG and DTDs, very often it is used as an adjunct to supplement the intrinsic weak points of grammars if necessary, or to express constraints that may belong to a different conceptual layer such as business rules.

What makes Schematron unique?

Schematron is very simple (only five important elements), very powerful (it can express many kinds of constraints impossible in other schema languages), very diverse (it can be used for business rules, reports as well as the kinds of static constraints usually associated with schemas.)

It places particular emphasis on capturing constraints in human language assertions and generating appropriate human-language diagnostics: this allows a level of user-friendliness not available in other schema languages.

As well, the phase concept allows constraints to be grouped and particular sets of groups checked, rather than all constraints: this can be used for progressive validation (e.g. coarse-grain validation first, validate links next, and so on), or user-role selectable validation, or multi-version schemas.

Schematron schemas can validate co-constraints (if some data is one value, some other data should be constrained to certain values) and even jump across links and between XML documents to check constraints. The diagnostics facility allows multi-lingual schemas.

What implementations are available?

The major implementation is the skeleton implementation at Schematron.com. This is an open source implementation which is quite mature, having been in continuous use and development since early 2000. This implementation uses XSLT1 and XSLT2 and can run in any environment that can invoke XSLT transformations.

However, while ISO Schematron can (and in some cases has) been implemented directly, for example in languages such as .NET or Java, often the XSLT implementation is well optimized. The SAXON 9 XSLT process is recommonded, however the skeleton has been tested with many other XSLT engines.

How is Schematron used?

The main implementation is the iso_schematron_skeleton implementation from www.schematron.com uses XSLT1 or XSLT2, which allows customized outputs to any format including text using metastylesheets and provides several such customizations (the iso_svrl stylesheet being one of them. It is straightforward for an XSLT programmer to integrate Schematron into a new system.

The ISO Schematron standard also specifies an XML language called SVRL (Schematron Validation Report Language) and this is becoming increasingly popular to represent the output from a validation (by default Schematron implementations do not stop at the first error as grammar-based validators do) so the SVRL report can show errors throughout the entire document. This SVRL report can the be used by further application or functions.

Is Schematron tied to XSLT 1.0?

By default, Schematron uses the XPath language as used in XSLT 1.0, and is typically implemented by converting the schema into an XSLT 1.0 script which is run against the document being validated. However, ISO Schematron also allows XSLT 2.0 to be used, and this is becoming an increasingly popular choice because of the extra expressive convenience of XPath 2.0: a different skeleton is available for this.

What about Schematron 1.5?

Schematron 1.n were the original pre-standard version of Schematron from Academia Sinica, Taiwan. Schematron 1.6 was the last version of that line, and the ISO Schematron implementation has taken over. Schematron 1.n and ISO Schematron use different namespaces, but a Schematron 1.n schema can be converted into an ISO Schematron schema with minimal changes. Schematron 1.n is now obsolete and the Schematron 1.n skeleton is no longer maintained; ISO Schematron is the appropriate choice for new projects.

News

News

March 2010 - New release of Schematron validator code. New release of Schematron for Ant task.

March 2010 - Final editor's draft of ISO Schematron second edition delivered to ISO/IEC JTC1 SC34 WG1 for deliberation

July 2009 - Probotron open source runner for ISO Schematron for Java and .NET released. Alex Brown at the helm.

May 2009 - XMLBlueprint XML Editor version 7 has been released. Among the new features is support for ISO Schematron - Validation and XML Completion, including a Schematron editor. Documents can be associated with Schematron schemas using a processing instruction <?blueprint schematron="book.sch"?>

April 2009 - Oxygen editor supports ISO Schematron, including the XSLT2 binding. It seems to provide good access to many of the options in the scripts. It continues to support Schematron 1.5 as well. Documents can be associated with Schematron schemas using a processing instruction <?oxygen SCHSchema="file:/C:/work/personal.sch" type="xml"?>

March 2009 - beta version of XML Schemas to Schematron converter (a pipeline of XSLT2 scripts with a sample ANT script) available.

February 2009 - candidate release for stable implementation!

July 2008 - new version of the beta implementation. The next release will not be marked beta!

October 2007 - new versions of the beta implementation of ISO Schematron are available with minor changes only. From this version on, there will be two versions of the skeleton implementation: one for the SAXON XSLT2 processor and one for XSLT1 and EXLST processors.

February 2007 - Beta Ant Task for Schematron available. Documentation (PDF) also available. The project is sponsored by Allette Systems and Topologi Pty. Ltd. and will be available under an OSS license. Programmers: Christophe Lauret and Willi Ekasalim.

January 2007 - The beta implementation of ISO Schematron is now available. This XSLT-based implementation is the successor to the Schematron 1.5 stylesheets in wide-spread use (and follows the same "meta-stylesheet" design pattern.) It implements almost all ISO Schematron (only abstract patterns are yet to be implemented) and is the result of collating years of suggested improvements from Schematron users; an implementation status document is available. The implementation is structured as a "skeleton" that allows output functions to be overridden by customized validators; basic API documentation is available.

January 2007 - Accompanying the beta release of ISO Schematron skeleton is several validators that produce customised output. Schematron Terminator is a validator that halts with an error code when the first error is detected. Schematron SVRL is a validator that generates Schematron Validator Report Language XML documents, which are specified by the ISO Schematron standard. Notes on the page detail a technique for using a Schematron schema to test SVRL documents, and on how the new flag attributes can be used.

January 2007 - ISO SVRL (Schematron Validation Report Language) implementation now available from this site. SVRL is an XML language to present the results of validating with a Schematron schema. It can be used for testing implementations, benchmarking, and for collecting validation data to be onsent to other formatting or reporting stages. SVRL is Annex D of ISO Schematron.

November 2006 - ISO Schematron specification now available free from ISO under Publicly Available Specification program.

July 2006 - Article on IBM DeveloperWorks: Apply Schematron constraints to XForms documents automatically

July 2006 - Quote from Microsoft's Program Manager for XML Standards Mike Champion I encourage people who hit the wall with XSD in the Microsoft environment to try out Schematron constraints, use the reference XSLT implementation, and see if that works for them.

June 2006 - US military-related thinktank MITRE's Open Vulnerability Assessment Language (OVAL 5.1) uses Schematron.

May 2006 - Schematron is now published as an ISO Standard

March 2006 - Schematron used intensively in ACORD insurance application for the London Market: London Market Implementation of ACORD DRI Messages and Data (PDF) See also the Market Reform Group's page Schematron - the benefits and the Lloyd's press release Schematron presses the right buttons

February 2006 - Users and developers mail-list schematron-love-in revived thanks to Betty Harvey ECC and Washington XML Users Group. Users stirring in preparation for the advent of ISO Schematron.

February 2006 - Announcement of SchematronWiki, a wiki (informal collababorative web-bsed set of linked information pages) for Schematron.

February 2006 - Notice received from ISO secretariat that final editorial changes have been accepted, national votes in order. Expect final acceptance and publication in April.

August 2005 - Final text and reference implementation of ISO Schematron in preparation (delay due to illness of editor)

July 2005 - ISO Schematron accepted for ISO Standard after final internalational vote. ISO SC34 proposes that the ISO Schematron specification should be freely available (being based on a previously existing technology.)

February 2004 - Misc. editorial improvements to Committee Draft spec available.

February 2004 - Schematron 1.5 validation available in new Topologi Judge validation utility and Topologi Markup Editor 2.4 editor

January 2004 - Schematron 1.5 validation support added to Oxygen XML editor

November 2004 - final Committee Draft specs for ISO Schematron now available in PDF, RTF and HTML

October 2004 - SCHEMATRON.COM goes live!

September 2004 - Committee Draft of ISO Schematron available.

August 2004 - Schematron link to this site added to official Sun documentation for Java API for XML validation.


SCHEMATRON.COM is a site to encourage and support implementations and users of the forthcoming standard ISO Schematron.

If you have news, please email rjelliffe(at)allette.com.au

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