Compatibility articles

This page provides links to a number of works on enabling loosely coupled evolution of web and web service components using XML Schema, WSDL, WS-Policy and other languages authored by myself, then other authors.
July 2007

• W3C Web architecture XML Versioning finding for issue 41-XMLVersioning
  • versioning terminology
  • versioning strategies
  • Versioning strategies using XML including XML Schema
• The W3C Architecture of the World-Wide Web, particularly in the areas of formal models, diagrams, extensibility, versioning.
• XML.com articles
  • A theory of compatible versioning (Dec 2006)
  • Designing extensible and versionable languages (Oct 2004)
  • the first iteration XML.com article on Versioning XML Languages(Dec 2003)
• WSDL 2.0 Primer section on versioning
• WS-Policy
  • Extensibility and Versioning of Policies
  • Extensibility and Versioning of the WS-Policy Language
• Guide to Versioning using new Schema 1.1 features
• Google search of my blog
• Which Schema wildcard namespace value to use, ##other or ##any?
• Forwards compatibility with version #s requires version # mapping
• http://www.pacificspirit.com/blog/2007/04/19/what_do_version_identifiers_identify
• SOA Principles
• XML 2004 talk extending and versioning XML Languages( 200K PDF), a view of the previous articles.
• Providing Compatible Schema Evolution, a paper that examines todays and potential tomorrow solutions for compatible evolution
• Examining Element and Wildcards as siblings
• Four major constraints in achieving Loosely Coupled Web Services, an article about extensibility, versioning, asynchrony and standardization.
• Web Services or Distributed Objects looks at extensibility and whether Web services are "Webish" or Distributed Objects
• I've gradually come to the realization that versioning is all about substitubility, and substitutability really needs to be in V1 to achieve forwards compatibility.
• Compatibility and Evolution in an Asynch World
• Where substitution Rules can be found
• Why putting extra structure in V1.0 is good
• Protocol Extensibility and Versioning
• My ongoing attempt at defining a Formal Compatibility Definition.

Other Authors

• RIGS applied the rules in the versioning article in their section on extensibility and versioning at rig0006
• David Bau's Theory of Compatibility Part 3 where he proposes validation by projection
• David Bau's Encapsulation or Representation article, comparing objects to formats
• Eve Maler's discussion on SAML Versioning
• Eve Maler's Substitutability whitepaper written for the XML Schema WG in 1999
• Eve Maler, Ashok Malhotra, Allen Brown's Schema Refinement Task Force report, W3C password protected
• OASIS CAM has a committee on assembling documents.
• Semantic web/RDF/OWL and extensibility/versioning. OWL has Versioning information.
• Dublin Core has namespace policies and the terms contain isVersionOf, hasVersion, isReplacedBy, and replaces terms.
• James Clark has written NRL to combine independent namespace into documents with multiple schema languages
• Mathew Fuchs wrote a paper on using XSLT to do substitution
• Henry Thompson proposed how to do extensibility by applying the must Ignore unknown content using an innovative two pass validation with filtering technique
• Dare's MSDN article introducing the sentry technique.

There are numerous discussions on more tightly coupled evolution of services, particularly requiring some action on both sides.

• Arofan Gregory and Eduardo Gutentag's work on UBL Versioning
• UBL Naming rules and my comments

WSDL

• WSDL 2.0's Application Data feature, for specifying SOAP or HTTP Headers via extensibility