© 1999–2021 Rick Jelliffe. PageSeeder and hosting generously provided by Allette Systems (Australia)
A language for making assertions about the presence or absence of patterns in linked XML documents.
Overview
schematron.com
A website for all things Schematron.
- Scores of articles on topics about Schematron, XML, Standards and more. Use the Search panel at the top, or browse them using the menu for News, Standards, Hints, Opinion, and Off-Topic.
- Links to Open things: implementations, standards, licenses, documentation
- Specialist material: preferred academic citation conventions, procurement best practise.
- New: Dave Pawson's Schematron Tutorial is coming.
- New: The Schematron Open Documentation project is coming (4Q 2021)
NEWS: Schematron helping our fight against COVID: in the US, real-time data on Emergency Medical admissions and causes is collected by National Emergency Medical Services Information System (NEMSIS). Schematron has allowed them a practical route to having subject-matter experts specify rules in plain English, then developers implement exactly those rules. Read their excellent Schematron Guide, or see their online Library of national and state-level Schematron Rules. (Hint: try “PA”)
Open Source Implementations
There are two Open Source implementations of Schematron for XSLT at GitHub:
- The skeleton implementation, which was the original code by Rick Jelliffe with numerous contributions. It is
not expected that this code will be developed further.
- SchXslt [ʃˈɛksl̩t], a cleaner re-implementation by David Maus, very compatible with the skeleton. The initial version only took 704 lines of code!
Search the web for implementations of Schematron in your language of choice: from Ant to Scala; these typically host the XSLT scripts and look after housekeeping.
As well, several systems are available which support Schematron embedded in other Schema languages: for example, the Apache Daffodil system allows Schematron embedded in the XSD-subset DFDL.
Open Standard
The international standard is ISO/IEC 19757-3. Available for $300 AUD.
The schemas for Schematron from the international standard are Open Source/Open Standards: they are available at this GitHub site.
- Release comments on the 3rd edition, 2020
- Release comments on the 2nd edition, 2016
ISO Schematron is an open standard, in the sense of the IEEE, ISOC, W3C, IETF, IAB, Foundation for Free Information Interchange (FFII), Free Software Foundation Europe (FSFE), requiring a formal, open process and unencumbered use.
Open Licensing
Coming Soon: Open Documentation and Tutorial
To assist users, implementers and evaluators, Schematron.com will be hosting two projects (under preparation):
Dave Pawson's Schematron Tutorial
A
The "Schematron Open Documentation" Project
Let's develop an unofficial, free and openly-available document that explains the technology of ISO Schematron!
(For discussion on how Schematron Open Documentation relates to Open Standard, see Procurement Best Practise for an Open Standard of Schematron.)
Community
Schematron is remarkable in how few questions people have about it. This is because the language is so small, and many questions people might have are actually XPath questions.
- Andrew Sales hosts the Schematronist mail-list.
- Betty Harvey's schematron-love-in mail list is no longer active but has archives.
- To raise issues for the ISO Schematron standard, use the GitHub Issues facilities on Tony Graham's schematron-enhancement-proposals.
What is Schematron used for?
Schematron is used for business rules validation, data reporting, general validation, quality control, quality assurance, firewalling, filtering, constraint checking, naming and design rules checking, statistical consistency, data exploration, transformation testing, feature extraction, house-style-rules checking.
It is use in sectors such as finance, health, aerospace, homeland security, tax, scientific computing, and publishing.
In the long run, I think Schematron may well be the XML project’s greatest technical
legacy to the world.
Simon St Laurent, Technical Journalist and O’Reilly Editor, xml-DEV list, 19 May 2016
Schematron Topics
- Fundamental Structural Patterns Bolognese
- Highly Generic Schemas
- Quasi-static and quasi-dynamic constraints
- Islands of validity
- Standard severity levels
- The most common programming error with Schematron
-
From Grammars to the Schematron (PDF) (1999) - the first public presentation of Schematron, at ASCC, Academia Sinica, Taiwan, explaned in terms of cohesion and coupling.
xsd2sch
It may seem impossible, or mad, to attempt to convert XSD to Schematron; or, rather, to partly implement XSD in XSLT 2 through Schematron. In 2007-2008, JSTOR funded an exploratory project at Allette Systems to write such a converter from XSD to Schematron, for a large subset they specified.
The techniques we developed were detailed in a long series of articles on the O' Reilly website: Converting XML Schemas to Schematron, which are now collected here with the related articles from the same time.
The XSLT2 code is available on GitHub under the MIT license.
Current
- SchXslt - Schematron engine in XLST
- XSLT 1,2,3
- uses same pre-processors as the skeleton
Recent
- Schematron skeleton - Schematron engine in XSLT
- XSLT 1,2
- not actively maintained now
Ancient
- Topologi Schematron Validator - 20-year old desktop application in VB
- Pre-ISO Schematron 1.6
- Free to use, not open source
- Supports xsd, RELAX NG, DTD, schematron in XSD or RELAX NG
Beyond Schematron
One good bubble deserves another. If RAN is a markup language which can be divided into separate fragments and parsed by separate threads, it must also need a validation language that also can work on arbitrary segments without requiring content.
Apatak has some similarities in its pairwise approach to 2002's one-element Hook schema language.
Feature extraction discovers some general property of an XML document, to direct subsequet processing. Is it a New Zealand document or a Fijian? Does it use the old tags or the new ones? Is it a tax return with no income? Is it a form where the person claims to be both single and married? This can certainly be done with Schematron and SVRL.
However, Feature Grammars provides a simpler and more direct language and XSLT for it.
"All documents, views and metadata at all significant levels of granularity and composition should be available in the best formats practical from their own permanent hierarchical URIs.”
- RAN - Raw Access Notation (2021) - remove barriers to parallel lexing/parsing
- RAN - Raw Access Notation (2021) (initial PDF)
- The Goals of XML at 25: and the one change that XML really needs now
- The X Refactor (2018) - XML ecosystem refactored into 5 layers
- XMON combining XML and JSON (2017) - allow structs in start-tags
- Editor's Concrete Syntax (2002) - a lexical profile of SGML for coloring editors
- Feature Grammars - a little language for extracting general features of documents
- Hook - a one-element schema language using partial ordering
- RAN Apatak - streaming validation of arbitrary segments
- SHRVL - Schematron Hierarchical Report View Language - nested version of SVRL
- Probabilistic schemas, hidden Markov models, neural nets for XML
- Sugar-Free XSD - resolved XSD subset with Schematron validator
- Lightweight schemas above structs - inline Attribute Grammars in PIs
- XML Notation Schemas (1999) - a framework with pluggable mini-validators
- Weak Validation (1999) -the basics of "feasible validation" later implemented
- Using XSLT as a validation language (1999) - the start of the line of thinking that lead to Schematron
-
Family Tree of Schema Languages for XML (2007) (PNG)
Updates
- What's in Java 13-16 for XML Developers?
- What's in Java 11 for XML Developers?
- What's in Java 10 (and 9) for XML developers?
- XPath 3.1 adds Maps and Arrays, and new operators '!' '?' - so ~ LISP?
- Overview of Rust and Pony
- Can Intel ISPC help stagnant C get its mojo back?
- The Fastest Growing Programming Language of 2018?
Issues