Commentary by Mark Wahl, CISA
Organizing principles for identity systems:
Service (Schema) Modeling Language WG of W3C
(20070508)
Earlier this year the Service Modeling Language specifications were moved to the W3C, in a newly-formed Service Modeling Language (SML) Working Group (home page and charter).
The use of the word "Service" in the title of the specification can be confusing, and in the SML V1.0 submission the word "service" occurs only once outside of the introduction section.
The W3C Team comment on the SML submission states that
"W3C normally refrains from standardizing XML vocabularies for specific application areas, unless they have foundational character ... or very wide application .... Vocabularies for other areas are better standardized in other fora. But SML is not a conventional XML vocabulary. It defines no elements or attributes with any semantics specifically related to IT services or systems. Instead, it is at once a profile and an extension of XML Schema 1.0 and Schematron..."
One unusual aspect of this language is the use of endpoint references (EPR, as defined in WS-Addressing) as an alternative to URIs and XPointer for cross-document linking. According to WS-Addressing, an EPR must contain an address URI for an endpoint, and may also contain:
- wsa:ReferenceParameters
"A reference may contain a number of individual parameters which are associated with the endpoint to facilitate a particular interaction. Reference parameters are element information items that are named by QName and are required to properly interact with the endpoint. Reference parameters are also provided by the issuer of the endpoint reference and are otherwise assumed to be opaque to consuming applications. The use of reference parameters is dependent upon the protocol binding and data encoding used to interact with the endpoint.- wsa:InterfaceName
- wsa:ServiceName
- wsa:Policies
A reference may contain a number of policies that describe the behavior, requirements and capabilities of the endpoint. Policies may be included in an endpoint to facilitate easier processing by the consuming application, or because the policy was dynamically generated. However, embedded policies are not authoritative and may be stale or incoherent with the policies associated with the endpoint at the time when the interaction occurs."
At present, as the specifications have not yet been republished as W3C drafts, no issues have been raised beyond those in the W3C Team comments, and there's not been much activity on the WG mailing list.