Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, March-04-2009 Attendees Mike Beckerle(Oco) Alan Powell (IBM) Steve Hanson (IBM) Tim Kimber (IBM) Apologies Dave Glick (drac) 1. XML Schema 1.1 It was agreed that the lack of support for Schema 1.1 in tools, libraries etc would be an inhibitor to DFDL implementations so it was agreed to remain on XML schema 1.0 . SH highlighted the main isuues with staying on XSD 1.0 1) xs:all improvements - relaxing min/max occurs, allowing wildcards, I don't see an alternative to our current proposal of dfdl:sequenceKind. 2) weakened wildcard Either live with this restriction, or say that the DFDL parser will implement the 1.1 rule where an optional element takes precedent over a wildcard and say that if you use this feature of DFDL, you should avoid XML schema tools that implement this UPA check. (It is my understanding that many tools that validate XML Schema for correctness do not include the UPA checks). These issues need to be resolved. It was noted thet Schema 1.1 assert only allow reference to children of the item with the assert and that it would be desirable if DFDL was compatible. As there are dfdl use cases were reference to earlier fields is required AP to investigate if assigning earlier fields to variables in sufficient. 2. DFDL;ASSERT and DFDL:DISCRIMINATOR Discussion to clarify the semantics of assert and discriminator. Decided that dfdl:discriminator should only be used to resolve choices. TK to investigate if there are other use cases where discriminator would be useful. dfdl:assert is to ensure that a document is well formed which, while possibly applying similar tests, is separate from validation. Confirmed that assert cannot be turned off. AP to document semantics. 3. Reducing number of properties General agreement to reduce properties when they are redundant and don't support a common use case. LengthKind=NullTerminated, typeSubstitution, and trimkind.will be removed. dfdl:format specialization such as dfd;:sequence were also discussed. It had been pointed out in emails that there are two stable options - Only dfdl:format with no specializations - Only specializations and no general dfdl:format. Supporting both dfdl:format and specialization was felt to be undesirable. SH point out that the second option was not practical for all constructs as complex type definitions which put properties in scope would require all possible properties. I was agreed that for dfdl v1 the specializations would be dropped. 4. AOB To be discussed - Escape Schemes - Consuming extraneous data after schema has be used. - 'Floating' definitions - Validation ranges and exclusion lists - Actions Next call 11 March 14:00 Meeting closed, 15:00 GMT Actions raised at this meeting No Action 033 04/03: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice. 034 04/03: AP remove redundant properties Current Actions: No Action 012 AP/SH: Update decimalCalendarScheme 10/9: Not allocated yet 17/9: No update 24/9: Add calendar binary formats to actions 22/10: No progress 16/1: proposal distributed and discussed. Will be redistributed 21/1: add locale, 04/02: changed from locale to specific properties 18/2: Need more investigation of ICU strict/lax behaviour. 020 SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy 22/10: No progress 10/12: added how to decide to overpunch and sign position 11/02: proposal largely agreed. SH to make minor changes 18/02: AP to document unsigned type behaviour 25/02: no progress 023 MB: Review Schema 1.1 29/1: AP and SH to talk to Sandy Gao 04/02 Call arranged for Friday 11/02: Call took place. Identified useful changes. Consolidate with previous list. 04/03: decided to stay on Schema 1.0. 024 String XML type 025 Escape schemes 21/1: discussed requirements 04/02: AP/SH to describe behaviour for known length text fields. Need to discuss if comment escapes should be supported. 11/02 new draft distributed: 18/02: SH up document concerns 25/02: SH and AP have refined proposal ready for approval. 04/03: SH and AP have further refined proposal. 026 SH: Envelopes and Payloads 027 Property precedence tables 028 Variable markup 029 valueCalc (output length calculation) 031 DG: Review dfdl v033 11/02: Initial comments received 18/02: Will include work items 5 and 12. 032 DG: Investigate compatibility between DFDL infoset and XDM 033 04/03: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice. 034 04/03: AP remove redundant properties Closed actions: 034 Work items: No Item 001 String XML type (Ian P) - Apr 30, 2008 002 Escape schemes (Ian P) - Apr 30, 2008 003 Variables - ??, 2008 (Mike) 005 Improvements on property descriptions - ??, 2008 (All - split TBD) 006 Envelopes and Payloads (Steve) - Apr 30, 2008 007 (from draft 32) valueCalc (Mike) - ??, 2008 mostly complete 008 (from draft 32) Property precedence for writing (Steve) - under review 009 (from draft 32) Variable markup (Steve) - Mar 31, 2008 proposal needs writing up 010 (from draft 32) Assertions, discriminators and choice, including discussion of timing option (Suman) - Mar 31, 2008 * in progress * 011 (from draft 32) How speculative parsing works (combining choice and variable-occurence - currently these are separate) ??, 2008 (IBM) in progress 012 (from draft 32) Reordering the properties discussion: move representation earlier, improve flow of topics ??, 2008 (Alan) * not started * 025 Augmented infoset and unparsing (Alan) added but needs work 026 Remove duration complete - specification updated Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. 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