Open Grid Forum: Data Format Description Language Working Group

Weekly Working Group Conference Call
17:00 GMT, 05 Mar 2008

Attendees
Mike Beckerle (Oco)
Steve Hanson (IBM)
Ian Parkinson (IBM)

Apologies
Alan Powell (IBM), Simon Parker (PolarLake)


1. Discriminator Expressions
Recent discussions on the DFDL-WG email list need to be written up for inclusion in the specification. It would be useful, as discussed, to automatically generate discriminators when converting COBOL copybooks, C structs etc. to DFDL schemas. As Mike observed, this will be difficult as copybooks and header files do not typically contain enough information to generate descriminators.

2. UML diagrams
Steve is happier with the proposed UML diagrams now that they have been simplified. We had previously decided to include, in the specification, just the diagram showing the supported subset of XML schema.

Now the diagrams are simplified, Simon is planning to attempt to combine the three current diagrams into a single diagram. Mike suggested a difficulty with these diagrams; some concepts (for example, element references) are not treated as real components in XML schema but are used, by DFDL, as part of the scoping rules.

3. valueCalc examples
Mike has distributed a set of Powerpoint slides giving examples of calculated values, and thanks the group for the feedback. He will add an additional example showing output length calculation.

4. Remaining specification work
The plan for draft 32 need to be adjusted as we have now missed many of the planned dates. Steve's 'unparser property precedence' item is complete; and the discussion on assertions and discriminators has made good progress, and need final write-up by Suman. Work on speculative parsing still needs to be assigned an owner, probably from IBM's WTX team.

With regard to speculative parsing, Steve wondered whether this might affect the ability of an implementation to implement optimisations such as lazy parsing. Although this remains an implementation detail and not a subject to be covered by the DFDL specification, we will need to describe aspects of the behaviour of speculative parsing to be able to define uncertainty resolution in DFDL.

Mike will include a review of the list of outstanding work items in the agenda for next week's DFDL-WG call.

Meeting closed, 17:35 GMT



Ian Parkinson
WebSphere ESB Development
Mail Point 211, Hursley Park, Hursley, Winchester, SO21 2JN, UK



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