Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, Oct-07-2009 Attendees Mike Beckerle (Oco) Alan Powell (IBM) Steve Hanson (IBM) Peter Lambros (IBM) Stephanie Fetzer(IBM) Apologies Steve Marting (Progeny) Suman Kalia (IBM) 051 - New scoping rules A number of emails have pointed out minor flaws in the proposal from last week so we spent most of the call refining the proposal. 1. Top level xs:schema elements MAY have a dfdl:format annotation (but only one) 2. The top level xs:schema format annotation provides defaults for the dfdl properties for every DFDL-annotatable construct in the schema document. (update 1) They do not apply to any constructs in included/imported schema which may have their own defaults 3. local dfdl annotations on a construct of the schema take precedence over properties coming from the lexically enclosing top-level schema format annotation (if there is one) 4. when a property binding appears explicitly on a reference (element, type, or group), the same property binding cannot appear explicitly on the referenced global definition or declaration. (Schema definition error) 5. The merged explicitly defined properties from the reference and declaration/definition take precedence over the defaults applied to the declaration/definition, which take precedence over the defaults applied to the reference. 6. The same precedence rules apply to simpleType inheritance 7. There are no dfdl annotations on xs:complexTypes and xs:group declarations 8 Variables can still be used for 'parameterization' but expected to be the exception. Splitting dfdl:element and dfdl:simpleType properties. SH proposed that the dfdl:properties on an xs:element and xs:simpleType, currently are nearly the same should be separated so that as far as possible the representational properties are on the xs:simpleType and only the instance properties are on the xs:element. That is become more type oriented similar to XML schema. After discussion of the details, particularly where dfdl:length would be allowed we decided delay any decision until next week. It was noted that it will not be possible to change later. (update 1) The split also applies to xs:element and xs:complexType which would make xs:simpleTypes and xs:complexTypes symmetrical. 045: Resolving points of uncertainty An updated proposal was distributed and comments received. The comment were largely editorial and will be incorporated into the next version. AOB: Draft 36 was made available but proplems with gridforge prevented it being uploaded. Contact Alan Powell for a copy. Next call 14 October 13:00 UK for 2 hours Meeting closed, 15:05 Actions raised at this meeting No Action 060 Should dfdl become more type oriented and split dfdl:properties between element and simpleType/complexType 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. 08/04: Not discussed 22/04: AP to complete asap once the ICU strict/lax behaviour is understood. 29/04: No progress 06/05: No progress 13/05: Calendar has been added to latest spec version v034 but still a few details to clarify. 20/05: No Progress 27/05: No Progress 03/06: No Progress (low priority) 09/06: No Progress (low priority) 17/06: SH to check ICU code for lax calendar behaviour 24/06: no progress 01/07: no progress 15/07: no progress 29/07: no progress 05/08: no progress 12/08: no progress 19/08: Inconsistencies are being found in ICU behaviour so Calendars need reviewing again. 26/08: Specific three character short time zones may not be maintained during round tripping when there is more than one short form for a time zone offset. Because dates and datetimes in the infoset only maintain a time zone offset so on unparsing it isn't possible to say which short form will be selected for a particular offset when there is more than one possible. Need to document. 09/09: no progress 16/09: no progress 30/09: no progress 07/10: no progress 033 AP/TK: Assert/Discriminator semantics. AP to document. TK to check uses of discriminator besides choice. 08/04: In progress within IBM 22/04: Waiting for TK to return from leave to complete. 29/04: TK has sent examples shown need for discriminators beyond choice. Agreed. MB to respond to TK 06/05: Discussed suggestion of adding type indicator to discriminator. MB to provide examples. 15/03: Semantic documented in v034. MB to provide examples of need for scope indicator on discriminator 20/05: MB to provide examples of need for scope indicator on discriminator (but lower priority than action 029) 27/05: No Progress (lower priority) .... 19/08: No Progress (lower priority) 26/08: No Progress (lower priority) 09/09: no progress 16/09: no progress 30/09: no progress 07/10: no progress 037 All: Approach for XML Schema 1.0 UPA checks. 22/04: Several non-XML models, when expressed in their most obvious DFDL Schema form, would fail XML Schema 1.0 Unique Particle Attribution checks that police model ambiguity. And even re-jigging the model sometimes fails to fix this. Note this is equally applicable to XMl Schema 1.1 and 1.0. While the DFDL parser/unparser can happily resolve the ambiguities, the issue is one of definition. If an XSD editor that implements UPA checks is used to create DFDL Schema, then errors will be flagged. DFDL may have to adopt the position that: a)DFDL parser/unparser will not implement some/all UPA checks (exact checks tbd) b) XML Schema editors that implement UPA checks will not be suitable for all DFDL models c) If DFDL annotations are removed, the resulting pure XSD will not always be valid (ie, the equivalent XML is ambiguous and can't be modelled by XML Schema 1.0) Ongoing in case another solution can be found. 29/04: Will ask DG and S Gao for opinion before closing 06/05: Discussed S Gao email and suggestions. Decided need to review all XML UPA rules and decide which apply to dfdl. 20/05: SH or SKK to investigate 27/05: No Progress 03/06: The concern is that some dfdl schemas will fail UPA check when validation is turned on or when editted using tooling that enforces UPA checks. Renaming fields will resolve some/most issues. Need documentation that describes issue and best practice. 17/06: no change 24/06: no change 01/07: no prgress 15/07: No Progress (lower priority) 29/07: No Progress (lower priority) 05/08: No Progress (lower priority) 12/08: No Progress (lower priority) 19/08: Clarify that this action is to go through the XML UPA checks to assess impact on dfdl schemas and advice best practice. Name clashes is just one example. SH or SKK 26/08: No Progress (lower priority) 09/09: no progress 16/09: no progress 30/09: no progress 07/10: no progress 045 20/05 AP: Speculative Parsing 27/05: Psuedo code has been circulated. Review for next call 03/06: Comments received and will be incorporated 09/06: Progress but not discussed 17/06: Discussed briefly 24/06: No Progress 01/07: No Progress 15/07: No progress. MB not happy with the way the algorithm is documented, need to find a better way. 29/07: No Progress 05/08: No Progress. Will document behaviour as a set of rules. 12/08: No Progress 19/08: No Progress 26/08: No Progress 09/09: no progress 16/09: no progress 30/09: AP distributed proposal and others commented. Brief discussion AP to incorporate update and reissue 07/10: Updated proposal was discussed.Comments will be incorporated into the next version. 049 20/05 AP Built-in specification description and schemas 03/06: not discussed 24/06: No Progress 24/06: No Progress (hope to get these from test cases) 15/07: No progress. Once available, the examples in the spec should use the dfdl:defineFormat annotations they provide. ..... 19/08: No Progress (lower priority) 26/08: No Progress (lower priority) 09/09: no progress 30/09: no progress 07/10: no progress 051 Scoping rules. MB: to document change to scoping rules to satisfy implementation concerns 17/06: MB and SH proposals discussed. Needs further discussion 24/06: AP to update presentation with latest proosal 24/06: AP had updated presentation. MB to review 08/07: Discussed at length. Simple types will now take annotations. Variables will be used for parameters. 15/07: No further progress. Needs final write up. 29/07: No Progress 05/08: No Progress 12/08: No Progress 19/08: AP will document new syntax rules. 26/08: No Progress 09/09: AP has documented new scoping rules. Not discussed 16/09: Not disussed. AP to update element reference examples 30/09: Significant dissatisfaction with proposed new rules. New proposal developed during call. AP to document. 07/10: New proposal was refind. Details in minutes. 054 ICU DecimalNumber/ Calendar behaviour 15/07: No progress 29/07: No Progress. 05/08: No Progress. This action is to discover and document ICU behaviour. DFDL will do whatever ICU does. 12/08: No Progress 19/09: More examples of inconsistent behaviour discovered 09/09: no progress 16/09: no progress 30/09: no progress 07/10: no progress 056 resolve lenghtUnit=bits including fillbytes 12/08: No Progress 19/08: No Progress 26/08: No Progress 09/09: no progress 30/09: no progress 07/10: no progress 059 9/9: define how encoding, byteorder and floating point format externally 16/09: no progress 07/10: no progress 060 Should dfdl bcome more type oriented and split dfdl:properties between eleement and simpleType/complexType Closed actions: 057 Decide semantics and enumeration for 'parsed' occursCountKind 26/08: Subsequent discussion agreed on 'parsed' Need to agree semantics 09/09: no progress 16/09: occursxxx applies to array and optional elements. occursCountKind enumeration agreed. Semantics of 'parsed' are 'parse as many as possible. 30/09: Closed Work items: No Item target version status 003 Variables (from action 042) 036 done 005 Improvements on property descriptions not started 006 Envelopes and Payloads (from action 026) 036 done 007 valueCalc (from action 029) 036 done 011 How speculative parsing works (combining choice and variable-occurence - currently these are separate) (from action 045) awaiting completion of actions 045 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 033 Numeric data - what physical reps are allowed for what logical types (from action 020) 036 ensure all behaviour documented 036 Update dfdl schema with change properties 038 Improve length section including bit handling some improvement in 036 042 Mapping of the DFDL infoset to XDM not required for V1 specification 051 Revised scoping rules (from action 051) 036 awaiting completion of action 051 052 add entity for 'one or more white space characters' 036 done 053 name, baseFormat, selector, escapeSchemeRef, textNumberFormatRef, textCalendarFormatRef, binaryCalendarFormatRef attributes only 036 done 054 Add occureCountKind='parsed' 036 done 055 Make dfdl:initiatedConet discriminating (from action 58) 036 done 056 bidi support (action 044) 036 done 057 Properties that take an expression (action 55) 036 done 058 textPadCharacter %#rxx limitation and split to textxxxxPadCharacter 059 limit terminatorCanBeMissing to last element in schema. Ignore elsewhere. 060 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. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU