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Agenda for OGF WG call 27 May 2009
by Alan Powell 27 May '09

27 May '09

Note: the call is scheduled for 1 hour Agenda: 1. Go through actions. 2. Completing DFDL V1 3. AOB 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 026 SH: Envelopes and Payloads 08/04: Not discussed explicity, but recursive use of DFDL is tied up with this 22/04: Two aspects. Firstly compositional - do sufficient mechanisms exist to model an envelope with a payload that varies. Secondly markup syntax - this might be defined in the envelope. The second of these is very much tied up with the variable markup action 028, so will be considered there. SH to verify the composition aspect. 29/04: SH and AP working on proposal. related to Action 028 06/05: No progress 06/05: No progress 20/05: No Progress 027 SH: Property precedence tables 08/04: Not discussed 22/04: Two things missing from the existing precedence trees. Firstly, does not show alternates (eg, initiator v initiatorkind). Secondly, need a tree per concrete DFDL object (eg, element). SH to update. 29/04: No progress 06/05: SH is updating tables which will be ready for next call 13/05: SH emailed updated version. AP commented.. See minutes for issues and property changes. 20/05: Updated version circulated. Review before next call and be ready for vote. 028 SH: Variable markup 08/04: Discussed briefly at end of call, IBM to see whether there any use cases that require recursive use of DFDL. 15/04: Use case was distributed and will be discussed on next call. 22/04: The use case in question is EDI where the terminating markup for the payload segments is defined in the ISA envelope segment. The markup is modelled as an element of simple type where the allowable markup values are defined as enums on the type. But we need to handle two cases - firstly where the envelope is present, so the value used by the payload is taken from the envelope. Secondly where only the payload is present. Here we need a way of scanning for all the enum values, and adopting the one we actually find, when parsing. And using a default when unparsing. SH to explore use of a DFDL variable, where the variable has a default, but also has a type that is the same as the markup element - that way we get to use the enums without defining everything twice. 29/04: SH and AP working on proposal. 06/05: No progress 13/05: No progress 20/05: No Progress 029 MB: valueCalc (output length calculation) 08/04: Not discussed 22/04: Action allocated to MB, this is to complete the work started at the Hursley WG F2F meeting. 29/04: No progress 06/05: MB will have update for next call 13/05: MB will have update for next call 20/05: Some progress. will be circulated this week 032 DG: Investigate compatibility between DFDL infoset and XDM 08/04: No update 22/04: No update 29/04: No update 06/05: DG indicates will have update next week 13/05: see minutes 20/05: 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) 036 SH: Provide use case for floating component in a sequence 08/04: Raised 15/04: Use case sent and discussed. SH to do further investigation 22/04: IBM feedback from WTX team is that alternate suggested ways of modelling the EDI floating NTE segment have significant usability issues. The DFDL principle is that for a problem that can be expressed as two-layered, then two DFDL models are needed. The EDI NTE segment does not fall into this though, as its use is on a per sequence basis. Ongoing. 29/04: Agreed that need to be in V1. SH to make a proposal 06/05: No progress 20/05: SH has almost completed the proposal 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 038 MB: Submit response to OMG RFI for non-XML standardization 22/04: First step is for MB to mail the OGF Data Area chair to say that we want to submit 29/04: MB has been in contact with OMG and will sunbit dfdl. 06/05: MB has prepared response to OMG. Will send DFDL sepc v033 20/05: Response has been sent to OMG based on v034 039 SKK: Approach for creating Schema-For-DFDL xsds. 22/04: Resolve issue around multiple declarations needed for DFDL properties, perhaps using MB's meta approach 29/04: Don't like qualified attributes in long form. SKK to check there are no code gen implications, eg EMF. 06/05: SKK will send update by Friday 20/05: SKK and MB have produced Schema for DFDL, XSD dfdl subset and examples.. Close 042 MB: Complete variable specification. To include how properties such as encoding can be set externally. Must be a known variable name. 06/05: No progress 20/05: AP to make proposal 043 13/05: Types in the infoset. Currently infoset types have defined value space but that implies a parser would have to validate input. Is this correct? 20/05: SH No progress 044 13/05: Bidi 20/05: AP: will check what IBM products support. 045 20/05: AP: Speculative parsing No Action 045 20/05 AP: Speculative Parsing 046 20/05 AP: Document changes to simple type scoping 047 20/05 AP: Scoping for non-format annotations 048 20/05: AP investigate Restart 049 20/05 AP Built-in specification description and schemas Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell(a)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

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Action 029 outputValueCalc, variables (& also contribution for 026 - env. and payload)
by Mike Beckerle 26 May '09

26 May '09

Finally, here's a draft document about outputValueCalc, unparsing, and, variables, and such. Also attached is a zipped eclipse project containing two subdirs: outputValueCalc has examples of ... outputValueCalc, and variables has an envelope payload example enhanced and corrected somewhat over a prior one I sent. There's one entirely new concept here. I added an attribute to dfdl:defineVariable to specify whether the variable is for input (parsing) or output (unparsing). I was unable to get things to work in any simple manner without separating the two classes of variable. This doesn't seem too bad actually. ...mike Note: Please do not send sensitive data in unencrypted form in email. We cannot provide secure transit for email over the Internet. Mike Beckerle | CTO | Oco, Inc Tel: 781-810-2125 | 100 Fifth Ave, 4th Floor, Waltham, MA 02451 | mbeckerle(a)oco-inc.com | www.oco-inc.com <http://www.oco-inc.com/> Blog: cboblog.typepad.com <http://cboblog.typepad.com/> TURNING DATA INTO ANSWERS. FASTER THAN YOU EVER IMAGINED.

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DFDL: Support for 'floating' elements - proposal
by Steve Hanson 26 May '09

26 May '09

For approval on this week's call. This property permits instances of specific elements to 'float' in the representation, as is found in some real-world formats such as X12, with its NTE segment. Property Description floating Boolean Whether the occurrences of an element in a sequence can appear out-of-order in the representation. A value for dfdl:floating is only acted upon if the immediate parent is a sequence and dfdl:sequenceKind="ordered"; it is ignored otherwise. When parsing, and dfdl:floating is true, instances of the element may be encountered in the representation in any position within its containing sequence, but, if present, are placed into the infoset in schema declaration order. If the element repeats, instances do not need to be contiguous in the representation. When parsing, and dfdl:floating is false, instances of the element are expected in schema declaration order, and, if present, they are placed into the infoset in schema declaration order. It is a processing error if instances of the element are not encountered in schema declaration order. When unparsing, instances of the element are expected in the infoset in schema declaration order, and are output in the representation in schema declaration order. It is a processing error if instances of the element are not encountered in schema declaration order, It is a schema definition error if a sequence contains elements with dfdl:floating="true" and non-element content. Annotation: dfdl:element on a simple or complex local element or element reference Notes: a) It should be clarified in the spec that the instances of a repeating element in an unordered sequence do not need to be contiguous either. This is in keeping with the behaviour of xs:all groups in XML Schema 1.1. b) The consequence of the above statements of behaviour is that an ordered sequence of n element children and at least n-1 children with dfdl:floating="true" is equivalent to an unordered sequence with the same n element children. (This is deliberate design decision to aid consumability.) c) A complex element with dfdl:floating="true" can have as its content model a sequence with elements that also have dfdl:floating="true". d) This makes every element in a sequence containing one or more floating elements a point of uncertainty, in the same way as every element in an unordered sequence is a point of uncertainty. e) dfdl:floating is not allowed on a global element to be consistent with what we decided about occurs related properties, which only come into play when an element is used. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 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

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Minutes for OGF DFDL Working Group Call, May-20-2009
by Alan Powell 21 May '09

21 May '09

Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, May-20-2009 Meeting opened, 14:00 UK Attendees Steve Hanson (IBM) Mike Beckerle (Oco) Suman Kalia (IBM) Alan Powell (IBM) Apologies Dave Glick (drac) Agenda: 1. Go through actions. Updated below: 2. Codepage for text items in infoset. It is proposed that text values in the infoset should be ISO10646. Agreed 3. Annotations on Top Level element Highlighted usability problem that the top level element cannot inherit dfdl properties from scope as no complex type has be used yet. A reference to a defineFormat needs to on both the top element and its complex type. Suggested that could add a defineFormat property that used that defineFormat to set defaults for the schema but that would cause problems with include/import. Solutions seemed worse than the problem so will leave it as it is. 4 .Scoping of elements and Types MB has pointed out a problem with the current scoping rules and proposed that propoeties on an element should override those on its type. Discussion on whether an element was an instance of a simpleType or enclosed a simple type. For example if dfd:initiator on both element and simple type do you get one or two initiators.. Also discussed separating dfdl properties between element and type so that none were common. The need to be able to use XSD simple types directly made this impossible. Decided that an element is an instance of a simple type and that properties on the element override those on the simple type. Noted that this is different from complex type. Action: AP to document change to simple type scoping rules. 5. Scoping rules for assert/discriminator and other annotations The scoping rules for non-format annoations are not defined. AP to make a proposal 6. Need for the equivalent of WTX Restart Restart indicates where in the schema to restart parsing when unable to correctly parse content Could be viewed as an implementation decision. More investigation needed 7. Built-in Specifications Spec Section 23 Built-in Specifications TBD: this section gives the names, import URLs for, rep-property definition sets, property definitions, etc. for the built-in named format definitions The intention is that a small number of built-in specifications are provided for common format styles. 8. AOB Next call 27 May 14:00 UK Scheduled for 1 hour Meeting closed, 16:10 UK Actions raised at this meeting No Action 045 20/05 AP: Speculative Parsing 046 20/05 AP: Document changes to simple type scoping 047 20/05 AP: Scoping for non-format annotations 048 20/05: AP investigate Restart 049 20/05 AP Built-in specification description and schemas 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 026 SH: Envelopes and Payloads 08/04: Not discussed explicity, but recursive use of DFDL is tied up with this 22/04: Two aspects. Firstly compositional - do sufficient mechanisms exist to model an envelope with a payload that varies. Secondly markup syntax - this might be defined in the envelope. The second of these is very much tied up with the variable markup action 028, so will be considered there. SH to verify the composition aspect. 29/04: SH and AP working on proposal. related to Action 028 06/05: No progress 06/05: No progress 20/05: No Progress 027 SH: Property precedence tables 08/04: Not discussed 22/04: Two things missing from the existing precedence trees. Firstly, does not show alternates (eg, initiator v initiatorkind). Secondly, need a tree per concrete DFDL object (eg, element). SH to update. 29/04: No progress 06/05: SH is updating tables which will be ready for next call 13/05: SH emailed updated version. AP commented.. See minutes for issues and property changes. 20/05: Updated version circulated. Review before next call and be ready for vote. 028 SH: Variable markup 08/04: Discussed briefly at end of call, IBM to see whether there any use cases that require recursive use of DFDL. 15/04: Use case was distributed and will be discussed on next call. 22/04: The use case in question is EDI where the terminating markup for the payload segments is defined in the ISA envelope segment. The markup is modelled as an element of simple type where the allowable markup values are defined as enums on the type. But we need to handle two cases - firstly where the envelope is present, so the value used by the payload is taken from the envelope. Secondly where only the payload is present. Here we need a way of scanning for all the enum values, and adopting the one we actually find, when parsing. And using a default when unparsing. SH to explore use of a DFDL variable, where the variable has a default, but also has a type that is the same as the markup element - that way we get to use the enums without defining everything twice. 29/04: SH and AP working on proposal. 06/05: No progress 13/05: No progress 20/05: No Progress 029 MB: valueCalc (output length calculation) 08/04: Not discussed 22/04: Action allocated to MB, this is to complete the work started at the Hursley WG F2F meeting. 29/04: No progress 06/05: MB will have update for next call 13/05: MB will have update for next call 20/05: Some progress. will be circulated this week 032 DG: Investigate compatibility between DFDL infoset and XDM 08/04: No update 22/04: No update 29/04: No update 06/05: DG indicates will have update next week 13/05: see minutes 20/05: 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) 036 SH: Provide use case for floating component in a sequence 08/04: Raised 15/04: Use case sent and discussed. SH to do further investigation 22/04: IBM feedback from WTX team is that alternate suggested ways of modelling the EDI floating NTE segment have significant usability issues. The DFDL principle is that for a problem that can be expressed as two-layered, then two DFDL models are needed. The EDI NTE segment does not fall into this though, as its use is on a per sequence basis. Ongoing. 29/04: Agreed that need to be in V1. SH to make a proposal 06/05: No progress 20/05: SH has almost completed the proposal 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 038 MB: Submit response to OMG RFI for non-XML standardization 22/04: First step is for MB to mail the OGF Data Area chair to say that we want to submit 29/04: MB has been in contact with OMG and will sunbit dfdl. 06/05: MB has prepared response to OMG. Will send DFDL sepc v033 20/05: Response has been sent to OMG based on v034 039 SKK: Approach for creating Schema-For-DFDL xsds. 22/04: Resolve issue around multiple declarations needed for DFDL properties, perhaps using MB's meta approach 29/04: Don't like qualified attributes in long form. SKK to check there are no code gen implications, eg EMF. 06/05: SKK will send update by Friday 20/05: SKK and MB have produced Schema for DFDL, XSD dfdl subset and examples.. Close 042 MB: Complete variable specification. To include how properties such as encoding can be set externally. Must be a known variable name. 06/05: No progress 20/05: AP to make proposal 043 13/05: Types in the infoset. Currently infoset types have defined value space but that implies a parser would have to validate input. Is this correct? 20/05: SH No progress 044 13/05: Bidi 20/05: AP: will check what IBM products support. 045 20/05: AP: Speculative parsing Closed actions: 039 SKK: Approach for creating Schema-For-DFDL xsds. 22/04: Resolve issue around multiple declarations needed for DFDL properties, perhaps using MB's meta approach 29/04: Don't like qualified attributes in long form. SKK to check there are no code gen implications, eg EMF. 06/05: SKK will send update by Friday 20/05: SKK and MB have produced Schema for DFDL, XSD dfdl subset and examples.. SKK owner of dfdl schema and will update as properties change Closed 040 SH: LengthKind on complex objects. 29/04: All send comment before next call 06/05: See minutes. Agreed to remove lengthKind from sequence and choice. 20/05: Closed moved to workitem 041 AP: UnorderedInitiated 29/04: All: Review for next call 06/05: See minutes: Agreed to generalize to all sequences 20/05: Closed. Move to work item Work items: No Item target version status 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 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 027 Calendar schemes 034 032 Floating components 033 Changes from action 020 and 027 - renaming properties etc 035 Remove unorderedInitiated, add initiated content (a041) 036 Update dfdl schema with change properties (Suman) 037 Infoset text codepage 038 Improve length section Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell(a)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

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DFDL: Applying DFDL annotations to elements
by Steve Hanson 20 May '09

20 May '09

To apply DFDL annotations to a top-level element in a DFDL xsd, most modellers would use the dfdl:element dfdl:ref property to refer to a named dfdl:defineFormat block that set up the necessary defaults for all the DFDL properties. To avoid having to re-state the dfdl:ref property on every object that comprises the format, most modellers would also use the dfdl:complexType dfdl:ref property to scope the same dfdl:defineFormat block. The xsd would look like below. <xs:schema ...> <xs:annotation><xs:appinfo source=?http://www.ogf.org/dfdl/?> <dfdl:defineFormat name=?textFormat1"> <dfdl:format encoding="utf-8" separator="\n" representation=?text? lengthKind="delimited" /> </dfdl:defineFormat> </xs:appinfo></xs:annotation> ... <xs:element name="textDoc" dfdl:ref="textFormat1" dfdl:lengthKind="implicit"> <xs:complexType dfdl:ref="textFormat1"> <xs:sequence> ... </xs:sequence> </xs:complexType> </xs:element> ... </xs:schema> It's not possible to put DFDL defaults in scope for the whole format with a single dfdl:ref property. I think this is a side-effect of removing the dfdl:appliesTo property. If this is thought to be an issue, there are a couple of options: One is to say that a complex type can be the top-level object. This is the case with several XML based systems. It works with XML because the XML instance document provides the name of top level element in the infoset via its tag. This is not the case with DFDL where the name is commonly not carried with the format. So we'd have no name for the infoset. Another is to provide a new property on dfdl:defineFormat, which says this dfdl:defineFormat is the default for all top-level objects in the xsd. Any top-level object that remained silent as to its dfdl:ref would get the default applied. I'm not sure whether this makes the model too opaque though. No more so than the existing scoping rules, I suspect. Any other opinions or suggestions welcome. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 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

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Fw: DFDL: Action 027 - second rework of property precedence
by Steve Hanson 20 May '09

20 May '09

Alan, Mike Thanks for the feedback. Here is latest version that addresses all comments except where noted below. The biggest changes are: - Trimming & padding are now part of the 'extraction' & 'insertion' phases, and not conversion. - Complex element separated from simple element - Simple type / local element / global element distinctions called out - Repeat properties pulled forward into own phase Notes: 1) Mike - I agree that dfdl:inputValueCalc and dfdl:outputValueCalc should not be allowed in dfdl:format annotation (ie, scoping). Spec & xsds should be updated. 2) Mike - you say that escape schemes are needed when looking for initiators - we should discuss - I'm not sure this is a real requirement in practice - I've never come across this. 3) Mike - the DFDL parser/unparser is driven by model position - not by infoset position - you only get elements in the infoset. 4) Mike - I don't think that dfdl:initiatedContent is needed when unparsing. 5) Alan - encoding and byteOrder do apply for sequence, choice and any, because there could be markup involved. 6) Alan - lengthKind = 'pattern' - is this something that we should support on complex elements - assumed so for now. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 13/05/2009 10:25 ----- My markup on this attached - mostly using comment balloons on the side. Mike Beckerle | OGF DFDL WG Co-Chair | CTO | Oco, Inc. Tel: 781-810-2125 | 100 Fifth Ave., 4th Floor, Waltham MA 02451 | mbeckerle.dfdl(a)gmail.com Alan Powell/UK/IBM 11/05/2009 16:57 To Steve Hanson/UK/IBM@IBMGB cc dfdl-wg(a)ogf.org, dfdl-wg-bounces(a)ogf.org Subject Re: [DFDL-WG] DFDL: Action 027 - rework of property precedence - plus issues arising Steve Comments I don't think the tables answer the precedence of padding, escaping and encoding that we had when discussing escape schemes. On parsing it should be remove padding, remove escape characters, apply encoding. On unparsing it is the reverse but the tables look the same. I think the difficulty is that escape scheme is used for identification and extraction but also during conversion. I don't think the core properties (inputvaluecalc, etc) apply to sequence, choice or any. xxxPadKind is checked before xxxPadCharacter, xxpadxxx Calendar-binary. binaryCalendarFormatRef is only used when binCalRep = packed or bcd Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell(a)uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 From: Steve Hanson/UK/IBM@IBMGB To: dfdl-wg(a)ogf.org Date: 08/05/2009 17:24 Subject: [DFDL-WG] DFDL: Action 027 - rework of property precedence - plus issues arising I've created a separate property precedence for each schema object that can carry non-scoping DFDL properties (attached for review). The following issues were noted: 1) Missing property dfdl:textBooleanJustification - similar properties exist for string, number and calendar types. 2) What is the rule when the same DFDL properties occur on a xs:simpleType and a xs:element that uses that type? Does this work a) like element/group references (ie, properties combined with element winning) or b) like complex element and its sequence (ie, element and simpleType are considered separate objects)? I don't think section 10 covers this case. 3) Should we allow the DFDL nil & default control properties on a simple type? xs:nillable and xs:default are element only attributes in xsd. Spec currently allows this. 4) Should we allow DFDL occurs properties on global elements? Whether something repeats is a particle thing. Spec currently allows this. (IBM's WTX and MRM don't allow this). 5) Missing work item to get BiDi properties into shape and incorporated into spec. Should these be grouped, like escape scheme, calendar scheme, etc? Do they apply to calendar and number types? 6) Should dfdl:integerBooleanXXXRep be renamed dfdl:binaryBooleanXXXRep ? 7) We might want to reconsider the name of the new flag dfdl:initiated - it could be read that the xs:sequence itself is initiated rather than its children. 8) Should dfdl:initiated also apply to xs:choice? 9) Draft 33 property precedence had dfdl:outputLengthCalc - but that is not in the spec anywhere else? Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 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 [attachment "Property Precedence 034.doc" deleted by Alan Powell/UK/IBM] -- dfdl-wg mailing list dfdl-wg(a)ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg 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 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

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Agenda for OGF WG call 20 May 2009
by Alan Powell 20 May '09

20 May '09

Note: the call is scheduled for 2 hours Agenda: 1. Go through actions. 2. Codepage for text items in infoset. It is proposed that text values in the infoset should be ISO10646. 3. Annotations on Top Level element 4 .Scoping of elements and Types MB has pointed out a problem with the current scoping rules and proposed that propoeties on an element should override those on its type. 5. Scoping rules for assert/discriminator and other annotations 6. Need for the equivalent of WTX Restart Restart indicates where in the schema to restart parsing when unable to correctly parse content 7. Built-in Specifications Spec Section 23 Built-in Specifications TBD: this section gives the names, import URLs for, rep-property definition sets, property definitions, etc. for the built-in named format definitions 8. AOB 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. 026 SH: Envelopes and Payloads 08/04: Not discussed explicity, but recursive use of DFDL is tied up with this 22/04: Two aspects. Firstly compositional - do sufficient mechanisms exist to model an envelope with a payload that varies. Secondly markup syntax - this might be defined in the envelope. The second of these is very much tied up with the variable markup action 028, so will be considered there. SH to verify the composition aspect. 29/04: SH and AP working on proposal. related to Action 028 06/05: No progress 06/05: No progress 027 SH: Property precedence tables 08/04: Not discussed 22/04: Two things missing from the existing precedence trees. Firstly, does not show alternates (eg, initiator v initiatorkind). Secondly, need a tree per concrete DFDL object (eg, element). SH to update. 29/04: No progress 06/05: SH is updating tables which will be ready for next call 13/05: SH emailed updated version. AP commented.. See minutes to issues. 028 SH: Variable markup 08/04: Discussed briefly at end of call, IBM to see whether there any use cases that require recursive use of DFDL. 15/04: Use case was distributed and will be discussed on next call. 22/04: The use case in question is EDI where the terminating markup for the payload segments is defined in the ISA envelope segment. The markup is modelled as an element of simple type where the allowable markup values are defined as enums on the type. But we need to handle two cases - firstly where the envelope is present, so the value used by the payload is taken from the envelope. Secondly where only the payload is present. Here we need a way of scanning for all the enum values, and adopting the one we actually find, when parsing. And using a default when unparsing. SH to explore use of a DFDL variable, where the variable has a default, but also has a type that is the same as the markup element - that way we get to use the enums without defining everything twice. 29/04: SH and AP working on proposal. 06/05: No progress 13/05: No progress 029 MB: valueCalc (output length calculation) 08/04: Not discussed 22/04: Action allocated to MB, this is to complete the work started at the Hursley WG F2F meeting. 29/04: No progress 06/05: MB will have update for next call 13/05: MB will have update for next call 032 DG: Investigate compatibility between DFDL infoset and XDM 08/04: No update 22/04: No update 29/04: No update 06/05: DG indicates will have update next week 13/05: see minutes 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 036 SH: Provide use case for floating component in a sequence 08/04: Raised 15/04: Use case sent and discussed. SH to do further investigation 22/04: IBM feedback from WTX team is that alternate suggested ways of modelling the EDI floating NTE segment have significant usability issues. The DFDL principle is that for a problem that can be expressed as two-layered, then two DFDL models are needed. The EDI NTE segment does not fall into this though, as its use is on a per sequence basis. Ongoing. 29/04: Agreed that need to be in V1. SH to make a proposal 06/05: 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. 038 MB: Submit response to OMG RFI for non-XML standardization 22/04: First step is for MB to mail the OGF Data Area chair to say that we want to submit 29/04: MB has been in contact with OMG and will sunbit dfdl. 06/05: MB has prepared response to OMG. Will send DFDL sepc v033 039 SKK: Approach for creating Schema-For-DFDL xsds. 22/04: Resolve issue around multiple declarations needed for DFDL properties, perhaps using MB's meta approach 29/04: Don't like qualified attributes in long form. SKK to check there are no code gen implications, eg EMF. 06/05: SKK will send update by Friday 040 SH: LengthKind on complex objects. 29/04: All send comment before next call 06/05: See minutes. Agreed to remove lengthKind from sequence and choice. 041 AP: UnorderedInitiated 29/04: All: Review for next call 06/05: See minutes: Agreed to generalize to all sequences 042 MB: Complete variable specification. To include how properties such as encoding can be set externally. Must be a known variable name. 06/05: No progress 043 13/05: Types in the infoset. Currently infoset types have defined value space but that implies a parser would have to validate input. Is this correct? 044 13/05: Bidi Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell(a)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

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DFDL: Action 027 - rework of property precedence - plus issues arising
by Steve Hanson 19 May '09

19 May '09

I've created a separate property precedence for each schema object that can carry non-scoping DFDL properties (attached for review). The following issues were noted: 1) Missing property dfdl:textBooleanJustification - similar properties exist for string, number and calendar types. 2) What is the rule when the same DFDL properties occur on a xs:simpleType and a xs:element that uses that type? Does this work a) like element/group references (ie, properties combined with element winning) or b) like complex element and its sequence (ie, element and simpleType are considered separate objects)? I don't think section 10 covers this case. 3) Should we allow the DFDL nil & default control properties on a simple type? xs:nillable and xs:default are element only attributes in xsd. Spec currently allows this. 4) Should we allow DFDL occurs properties on global elements? Whether something repeats is a particle thing. Spec currently allows this. (IBM's WTX and MRM don't allow this). 5) Missing work item to get BiDi properties into shape and incorporated into spec. Should these be grouped, like escape scheme, calendar scheme, etc? Do they apply to calendar and number types? 6) Should dfdl:integerBooleanXXXRep be renamed dfdl:binaryBooleanXXXRep ? 7) We might want to reconsider the name of the new flag dfdl:initiated - it could be read that the xs:sequence itself is initiated rather than its children. 8) Should dfdl:initiated also apply to xs:choice? 9) Draft 33 property precedence had dfdl:outputLengthCalc - but that is not in the spec anywhere else? Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 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

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Grammar issue - simple and complex asymetry
by Mike Beckerle 19 May '09

19 May '09

The draft 034 grammar productions do not allow for a separate prefix/suffix for a simple type as distinguished from the element having that type. Draft 034 does allow for an element of complex type to have a separate prefix and suffix for the element itself and another one for the sequence or choice inside it. I've come to believe this is a mistake and I suggest a fix below. Right now the grammar is: Element = SimpleElement | ComplexElement SimpleElement = Prefix SimpleContent Suffix SimpleContent = StringText // terminal. No more prefixes/suffixes ComplexElement = Prefix ComplexContent Suffix ComplexContent = Sequence | Choice Sequence = Prefix SequenceContent Suffix Choice = Prefix ChoiceContent Suffix So, if I do: <complexType dfdl:initiator="[" dfdl:terminator="]"> ... <element name="y"> <complexType> <sequence dfdl:separator="," > <element name="x" type="int"/> <element name="z" type="int"/> </sequence> </complexType> </element> ... </complexType> I have two prefix opportunities. I can flatten the productions above to: ComplexElement = Prefix Prefix SequenceContent Suffix Suffix An instance of this type would look like [[[5],[6]]]. That is, for complex types, there are separate prefix and suffix regions for the element, and for the model-group which makes up its content. The first [ initiates element y. The second [ initiates the sequence The third [ initiates element x. This same behavior is not true for simple types: <complexType dfdl:initiator="[" dfdl:terminator="]"> ... <element name="y" > <simpleType> <restriction base="int"/> </simpleType> </element> ... </complexType> This can only mean [5]. The grammar, as formulated in draft 034, does not allow for more than one prefix or suffix. The [ is the initiator of element y. I believe we should fix this as follows. New grammar: Element = SimpleElement | ComplexElement SimpleElement = Prefix SimpleContent Suffix SimpleContent = StringText ComplexElement = ComplexContent // Note: no more surrounding prefix suffix. ComplexContent = Sequence | Choice Sequence = Prefix SequenceContent Suffix Choice = Prefix ChoiceContent Suffix The above grammar arranges for an element of complex type and its model group to both taken together specify a single prefix and suffix. Revisiting our example (just repeating it here): <complexType dfdl:initiator="[" dfdl:terminator="]"> ... <element name="y"> <complexType> <sequence dfdl:separator="," > <element name="x" type="int"/> <element name="z" type="int"/> </sequence> </complexType> </element> ... </complexType> An instance now would look like [[5],[6]] The first [ is the initiator of element y, which is the same as the initiator of the sequence that is its type. The second [ is the initiator of element x. (which is the same as the initiator of the int that is its type) I believe this is more sensible, as it makes the behavior of simple and complex types more similar. It begs the question of how one combines conflicting properties on an element with the properties on the type, and even the model group inside the type in the complex case. Because all these properties are describing the same syntax fields in the grammar. That's a separate topic in a subsequent email.

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elements and combining properties with their types
by Mike Beckerle 19 May '09

19 May '09

I spent some real time thinking about this issue today. Attached is a memo on the subject which is big enough that I didn't want to just make it an email body. Summary: I think current 034 semantics are broken and should be fixed along the lines of the element - overrides - type principle. The example in the scoping section is not right. But the issue has some depth to it. E.g., I think the grammar productions are broken currently and we need to fix those also. See attached. ...mike Mike Beckerle | OGF DFDL WG Co-Chair | CTO | Oco, Inc. Tel: 781-810-2125 | 100 Fifth Ave., 4th Floor, Waltham MA 02451 | <mailto:mbeckerle.dfdl@gmail.com> mbeckerle.dfdl(a)gmail.com

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