Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 14 Nov 2007 Attendees Geoff Judd (IBM) Steve Hanson (IBM) Suman Kalia (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Apologies Mike Beckerle (IBM) 1. Information Set Proposal Following last week's review of the Information Set proposal, Simon updated the proposal and distributed a new draft, version 7. Alan queried the reference to empty lists under "No Value", asking if this was necessary as DFDL does not use a concept of lists - this is carried over from the XML Information Set specification, and is only theoretical. The proposal will be distributed wider within IBM to solicit final comments. 2. Review of Revised DFDL Data Grammar Mike has updated the Data Grammar portion of the DFDL specification, to take into account the InfoSet proposal, and distributed this via the DFDL-WG mailing list. The meeting reviewed the revised grammar, touching upon the following points: Both the ComplexContent and ComplexElement productions include a "Prefix" element. Alan asked whether this duplication was necessary. Steve and Simon noted that this had not changed during the revision and that there are cases where this is useful. The meeting agreed not to change this. Alan asked why we need both Element and ComplexContent in the SequenceItem production. Element effectively introduces a name. Simon noted that most of the changes were in the productions, and wondered what influence the InfoSet proposal actually had on the specification. Steve said that there had been real changes, for example with SimpleElement and ComplexElement. Steve observed that Prefix and Postfix Separators no longer appear in the productions table. The meeting agreed that these were probably no longer necessary, and that this was a useful simplification, but to check this with Mike. 3. Object Constraint Language The UML diagram in the revised InfoSet proposal uses Object Constraint Language1 (OCL) to specify an invariant on the Element class. Simon asked the meeting to consider whether this might be a useful approach in other sections of the DFDL specification, in particular when describing parser behaviour. Suman was concerned that it might prove useful only for specifying parser internals which should not be covered in the language specification. 4. Other Business Suman asked if we need to define a parser API. Steve suggested that this should not form part of the language specification, but that there may need to be other specification documents. Steve and Alan will be compiling a list of remaining work items to move the specification towards completion. Work has started within IBM, to attempt to describe a number of industry standard data formats, including SWIFT and ISO 8583, using DFDL. Simon has a long standing work item to attempt to describe a number of custom application formats. These efforts should help validate the utility of DFDL and suggest specification revisions. Thanksgiving is next week - will this affect attendence of next weeks meeting? Meeting closed 17:35 GMT Actions Mike to comment on the omission of initial prefix Separators and final postfix Separators from the productions table, in the revised DFDL Data Grammar. Are these intended to be covered by other elements in the productions, or do they need to be added? References Object Constraint Language; specification at http://www.omg.org/technology/documents/formal/ocl.htm Ian Parkinson WebSphere ESB Development Mail Point 211, Hursley Park, Hursley, Winchester, SO21 2JN, UK Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU