Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, July 21-2010 Attendees Steve Hanson (IBM) Alan Powell (IBM) Stephanie Fetzer (IBM) Tim Kimber(IBM) Apologies Mike Beckerle (Oco) Suman Kalia (IBM) 1. Current Actions Updated below 2. Alignment of children when forward references. Expressions with forward references require caching of serialized output which is difficult when children have alignments that are greater that their parent. Agreed that 'the alignment of a child must be less than or equal to the alignment of its parent'. This allows serializing parts of the tree without having to redo alignments. 3. teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. Meeting closed, 16:30 Next call Wednesday 28 July 2010 15:00 UK (10:00 ET) Next action: 108 Actions raised at this meeting No Action 106 2. Alignment of children when forward references. Expressions with forward references require caching of serialized output which is difficult when children have alignments that are greater that their parent. Agreed that 'the alignment of a child must be less than or equal to the alignment of its parent'. This allows serializing parts of the tree without having to redo alignments. Closed 107 3. teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 21/07: work continues 085 ALL: publicize Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over andcan we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 086 AP: Nils and Defaults during unparsing - update table 31/03: TK to documetn use cases for parsing 14/04: Investigate new property to control empty string behaviour. 21/04: After investigation a new property is not required. New rules developed and tables updated. Need examples of complexTypes to confirm tables apply. Review Nils, defaulting spec section. 05/05: Discussed defaulting complex elements. Tables updated but need to add terminator. SH; to confirm WMD behaviour when infoset item has no value on unparsing Need to describe defaulting choices. 15/05: More discussion. Alan updating sections 26/05: Discussed draft updates. Stephanie to confirm asserts do not make an element required. Alan will update draft.. All: review rest of draft. 02/06: Alan updated description. Please review. Discussed Stephanie's example using discriminators. Decided no changes needed. 16/05: went through Steves comments. Steve to update draft. 23/06: Steve's updates to the rules discussed. See minutes. Rest of document needs updating. 30/06: Discussed Alans updates. Some corrections. Alan will send out updated copy for review before next call. 07/07: Discussed Alan updates and Tim and Steve's comments. Still some corrections and updates. 14/07: Discussed Alan updates (v9) Still some corrections and updates. 21/07: Discussed Draft 10. Shouldn't mention input/outputValueCalc in this section. Mention defaulting in calculated values section. Move details of nilValue from nilKind property. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to porcessing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will proce some examples of how this could be used. 102 Clarify the specification of error reporting from a DFDL processor - section 2.3 needs to be updated 21/07: Section is not clear. Alan will update. 103 Asserts and discriminators - specify the scope of forward references. Must be downward-only. The expression must be resolvable by the time the component on which it is positioned goes out of scope - otherwise it is a processing error. 21/07: Agreed 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. Closed actions No Action 105 Grammar for DFDL expression - currently allows multiple predicates on a single expression. Sounds as if this was unintended. 21/07: Current definition is incorrect: Will delete predicateList from the grammar and replace with predicate. Closed 106 2. Alignment of children when forward references. Expressions with forward references require caching of serialized output which is difficult when children have alignments that are greater that their parent. Agreed that 'the alignment of a child must be less than or equal to the alignment of its parent'. This allows serializing parts of the tree without having to redo alignments. Closed Work items: No Item target version status 005 Improvements on property descriptions not started 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 036 Update dfdl schema with change properties ongoing 042 Mapping of the DFDL infoset to XDM none not required for V1 specification 070 Write DFDL primer 071 Write test cases. 083 Implement RFC2116 105 AP: Describe trailingSkipBytes for delimited formats. Alan suggested 'dfdl:terminator must be specified and not empty if dfdl:lengthKind is delimited or endOfParent.' 106 AP: Skip Bytes should allow bits Ageed that it should be possible to specify bits. - LSB and TSB renames to dfdl:leadingSkip, dfdl:trailingSkip - units are specified by dfdl:alignmentUnits. 107 Remove timing from dfdl:assert 108 AP: Confirm behaviour of defaulting with various occursCountKinds and separator policies. 30/06: Decided that defaulting for variable occurrence arrays should always be to minOccurs. If separatorPolicy is 'required' then just the separators will be output up to maxOccurs and unbounded is an error. 109 define semantics of choiceKind 'fixedLength' dfdl:choiceKind becomes dfdl:choiceLengthKind with emuns 'implicit' (length of selected branch) and 'explicit' ( length specified by dfd;choiceLength) New property dfdl:choiceLength 110 nilIndicatorPath and nilIndicatorIndex properties 14/07: As part of nils default discussion the WG decided to drop dfdl:nilIndicator and dfdl:nilIndicatorIndex 111 AP: using textStringPadCharacter with charRef '%#r' on multi-byte encoding 14/07: Although there was some merit in having separate textPadKinds it was felt it was too late to make the change. The property descriptions (for numbers, calendars and booleans as well) will be improved. Closed 112 Alignment enumerations when dfdl:lengthUnits = 'bits' When alignmentUnits='bits', the rule that alignment must be 1,2,4,8 etc or multiple of 2 looks rather hard to justify. It was agreed to remove the restriction on aligmentUnits for both 'bytes' and 'bits'. Closed 113 Grammar for DFDL expression - currently allows multiple predicates on a single expression. Sounds as if this was unintended. 21/07: Current definition is incorrect: Will delete predicateList from the grammar and replace with predicate. Closed 114 2. Alignment of children when forward references. Expressions with forward references require caching of serialized output which is difficult when children have alignments that are greater that their parent. Agreed that 'the alignment of a child must be less than or equal to the alignment of its parent'. This allows serializing parts of the tree without having to redo alignments. Closed Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell@uk.ibm.com 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