January 2008 - dfdl-wg - lists.ogf.org

Re: [DFDL-WG] DFDL property precedence - parsing - v1
by Steve Hanson 18 Jan '08

18 Jan '08

Hi Alan 1. We discussed breaking this precdence list down on a per DFDL object basis. This was predicated on the UML diagram being enhanced to show the allowable properties. 2. Yes, I should make that clearer 3. No, initiatorSeparator and initiator are disjoint, the former is specially for wildcards 4. No. Regards, Steve Steve Hanson WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 Alan Powell/UK/IBM 17/01/2008 16:42 To Steve Hanson/UK/IBM@IBMGB cc DFDL-Technical-Core, dfdl-wg(a)ogf.org Subject Re: DFDL property precedence - parsing - v1 Steve I interpret precedence to mean: the order the dfdl properties should be inspected and the order of dependency (ie prop y is only relevant if prop x is set) so As not all properties are relevant to choice, sequence etc shouldn't they be in the tree? Aren't all occursxxx properties dependent on max/minoccurs > 1? InitiatorSeparator dependent on initiator Separator dependent on Delimited? 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 Steve Hanson/UK/IBM 11/01/2008 15:02 To DFDL-Technical-Core, dfdl-wg(a)ogf.org cc Subject DFDL property precedence - parsing - v1 Requires FreeMind from http://freemind.sourceforge.net/wiki/index.php/Download Parsing: [attachment "DFDL Property Precedence (parsing) 001.mm" deleted by Alan Powell/UK/IBM] Writing: tbd Notes: - Precedence is from top to bottom recursively, so the top priority is dfdl:inputValueCalc, then dfdl:byteOrder, then dfdl:encoding, then it's children top to bottom, then dfdl:occursKind (you get the idea). Questions arising: - Does dfdl:escapeScheme apply when dfdl:lengthKind = endOfData ? - Confirm that only signed logical number can have a signed rep, and only unsigned logical number can have an unsigned rep ? (change from spec 028 to 030) - Should dfdl:terminator, dfdl:separator and dfdl:occursSeparator be lists (to handle alternative delimiters) ? (viz dfdl:nullValues) - Why isn't dfdl:nullIndicatorIndex encompassed by dfdl:nullIndicatorPath ? - Use of enum 'xpath' for dfdl:nullKind.? We've used "explicit" elsewhere and decorated syntax to indicate xpath for other properties. For nullKind maybe a better enum would be "external" or "remote" ? - The advanced text delimiter supplement needs revision - most of its content appears to be in the core. Main question is on prefix v infix v postfix separators and how that capability is to be specified. Regards, Steve Steve Hanson 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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Re: [DFDL-WG] DFDL property precedence - parsing - v1
by Alan Powell 17 Jan '08

17 Jan '08

Steve I interpret precedence to mean: the order the dfdl properties should be inspected and the order of dependency (ie prop y is only relevant if prop x is set) so As not all properties are relevant to choice, sequence etc shouldn't they be in the tree? Aren't all occursxxx properties dependent on max/minoccurs > 1? InitiatorSeparator dependent on initiator Separator dependent on Delimited? 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 Steve Hanson/UK/IBM 11/01/2008 15:02 To DFDL-Technical-Core, dfdl-wg(a)ogf.org cc Subject DFDL property precedence - parsing - v1 Requires FreeMind from http://freemind.sourceforge.net/wiki/index.php/Download Parsing: [attachment "DFDL Property Precedence (parsing) 001.mm" deleted by Alan Powell/UK/IBM] Writing: tbd Notes: - Precedence is from top to bottom recursively, so the top priority is dfdl:inputValueCalc, then dfdl:byteOrder, then dfdl:encoding, then it's children top to bottom, then dfdl:occursKind (you get the idea). Questions arising: - Does dfdl:escapeScheme apply when dfdl:lengthKind = endOfData ? - Confirm that only signed logical number can have a signed rep, and only unsigned logical number can have an unsigned rep ? (change from spec 028 to 030) - Should dfdl:terminator, dfdl:separator and dfdl:occursSeparator be lists (to handle alternative delimiters) ? (viz dfdl:nullValues) - Why isn't dfdl:nullIndicatorIndex encompassed by dfdl:nullIndicatorPath ? - Use of enum 'xpath' for dfdl:nullKind.? We've used "explicit" elsewhere and decorated syntax to indicate xpath for other properties. For nullKind maybe a better enum would be "external" or "remote" ? - The advanced text delimiter supplement needs revision - most of its content appears to be in the core. Main question is on prefix v infix v postfix separators and how that capability is to be specified. Regards, Steve Steve Hanson 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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DFDL: Minutes from OGF WG call, 16 Jan 2007 *CORRECTED*
by Ian W Parkinson 17 Jan '08

17 Jan '08

All, With thanks to Steve for the correction to 1(v). It is Steve, not Simon, who will be looking at whitespacing. Ian Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 16 Jan 2008 Attendees Geoff Judd (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Alan Powell (IBM) Steve Hanson (IBM) Suman Kalia (IBM) 1. Review of Minutes from last week OGF22 - No update from Mike. Specification Drafts - Steve and Alan have distributed a version of Mike's plan for the next few versions. of the specification with work items assigned to individuals. Simon asked for clarification regarding his item "2-level description (schema components)" - this covers reviewing and updating the DFDL schema abstract data model document (distributed by Steve, with the agenda for this meeting) for inclusion in the DFDL specification, to replace and extend the existing UML diagram. Expression Language - Alan will update and distribute a new draft of the expression language proposal. Property Precedence - Steve has prepared a proposal as a Freemind mind map and would appreciate any review comments, especially with regard to the questions distributed along with the proposal. The group briefly discussed some of these, and Steve will email Mike asking for his opinion on some of these issues. Regarding dfdl:escapeScheme, and how it applies when lengthKind=end of data - the specification plan includes a review of the escapeScheme mechanism and this issue can be discussed then. While discussing the enum used for dfdl:nullKind, Simon observed that this issue has not arisen in PolarLake's parser as it does not have a well-developed concept of null. Steve felt we should perhaps remove the Advanced Text Delimiter Supplement. Entity References - Alan and Ian have been looking at this, and will prepare and distribute a revised proposal. Steve will write a proposal to cover whitespacing. (Simon Parker left the meeting) 2. Property Precedence The group discussed Steve's proposal and its relation to the specification document. It was suggested that the specification could list the properties of each object in precedence order; and further that the UML diagrams could show which properties can be used with each object. Meeting closed, 17:40 GMT --- IBM review of UML for DFDL Schema Abstract Model For convenience, here is the set of comments from IBM regarding the UML diagrams in the schema abstract model document. General: All associations originating from DFDLSchema should have black diamond instead of empty diamond because DFDL schema object would be the owner of these objects. Cardinality of relationship is not explicitly shown; I think the default cardinality as per standard is 1 which won't be correct in this case. e.g. DFDLSchema would have more than 1 global elements/ types etc.. Likewise there would be black diamond relationship from Element Declaration/Simple Type Definition/ComplexType Definition to DFDL Annotation Base. (Suman) In the open source XML Schema model, there is no explicitly defined object for element reference and group reference. Same XSDElementDeclaration or XSDGroupDefintion are used to model references. It is determined programmatically and I think it would be better to use the open source XML schema model as source model and show relationship of DFDL Annotations attached to the XSD schema model. (Suman) UML for DFDL subset of XSDL : Need cardinality adding (Steve) White v black diamond not correct (Suman) What does 'ref' mean on the link from Particle to Element Declaration ? (Steve) Link from Complex Type Definition to Particle - this can only be to a Model Group subclass (Steve) May want to add the following pointer to make it complete: complex type definition -> (base type) -> complex type definition (Sandy) I know this is probably not needed by DFDL; but may help to include it for completeness. We have it for simple types; may confuse people if it's not on compelx types. (Sandy) UML for DFDL annotations on XSDL: Wondering whether this is necessary. It's a middle step, possibly only useful to implementors (Sandy) 1st bullet - talks about a limitation in the XSDL model - I'd like Sandy to take us through this. MRM carries annotations on groups and group refs.(Steve) 1st bullet - the practical limitation appears to be that you can't override the properties of a global group on a group reference, like you can with elements. Is this going to be an issue? (Steve) 4th bullet - prohibiting dfdl:discriminator on xs:choice seems sensible (Steve) Should "variable definition" be derived from "DFDL annotation base"? (Sandy) The current diagram suggests that "variable definition" can both be part of a format base or as a standalone annotation (outside of a format). Is this true? (Sandy) Can "hidden" be viewed as a specialized element reference? (Sandy) This only implies a "base class" pointer from "hidden" to "element reference". There really isn't much benifit in doing this. It just *feels* better. Don't feel strongly. (Sandy) UML for post-scope resolution and inheritance flattening: Haven't finished reviewing it carefully. (Sandy) Inheritance is used much more often in this diagram. e.g. "Any Element Wildcard" is derived from both "Occurrence Properties" and "DFDL properties Base". Is this intentional? Feels counter-intuitive to me. Components should *have* properties, rather than *be* properties. (Sandy) Wondering whether it makes sense to combine diagrams 2 and 3. That is, a single diagram that has everything inherited/flattered, but don't attempt to remove properties that are not used at runtime. e.g. keep DFDL Schema etc. (Sandy) 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

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DFDL: Minutes from OGF WG call, 16 Jan 2007
by Ian W Parkinson 17 Jan '08

17 Jan '08

Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 16 Jan 2008 Attendees Geoff Judd (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Alan Powell (IBM) Steve Hanson (IBM) Suman Kalia (IBM) 1. Review of Minutes from last week OGF22 - No update from Mike. Specification Drafts - Steve and Alan have distributed a version of Mike's plan for the next few versions. of the specification with work items assigned to individuals. Simon asked for clarification regarding his item "2-level description (schema components)" - this covers reviewing and updating the DFDL schema abstract data model document (distributed by Steve, with the agenda for this meeting) for inclusion in the DFDL specification, to replace and extend the existing UML diagram. Expression Language - Alan will update and distribute a new draft of the expression language proposal. Property Precedence - Steve has prepared a proposal as a Freemind mind map and would appreciate any review comments, especially with regard to the questions distributed along with the proposal. The group briefly discussed some of these, and Steve will email Mike asking for his opinion on some of these issues. Regarding dfdl:escapeScheme, and how it applies when lengthKind=end of data - the specification plan includes a review of the escapeScheme mechanism and this issue can be discussed then. While discussing the enum used for dfdl:nullKind, Simon observed that this issue has not arisen in PolarLake's parser as it does not have a well-developed concept of null. Steve felt we should perhaps remove the Advanced Text Delimiter Supplement. Entity References - Alan and Ian have been looking at this, and will prepare and distribute a revised proposal. Simon will write a proposal to cover whitespacing. (Simon Parker left the meeting) 2. Property Precedence The group discussed Steve's proposal and its relation to the specification document. It was suggested that the specification could list the properties of each object in precedence order; and further that the UML diagrams could show which properties can be used with each object. Meeting closed, 17:40 GMT --- IBM review of UML for DFDL Schema Abstract Model For convenience, here is the set of comments from IBM regarding the UML diagrams in the schema abstract model document. General: All associations originating from DFDLSchema should have black diamond instead of empty diamond because DFDL schema object would be the owner of these objects. Cardinality of relationship is not explicitly shown; I think the default cardinality as per standard is 1 which won't be correct in this case. e.g. DFDLSchema would have more than 1 global elements/ types etc.. Likewise there would be black diamond relationship from Element Declaration/Simple Type Definition/ComplexType Definition to DFDL Annotation Base. (Suman) In the open source XML Schema model, there is no explicitly defined object for element reference and group reference. Same XSDElementDeclaration or XSDGroupDefintion are used to model references. It is determined programmatically and I think it would be better to use the open source XML schema model as source model and show relationship of DFDL Annotations attached to the XSD schema model. (Suman) UML for DFDL subset of XSDL : Need cardinality adding (Steve) White v black diamond not correct (Suman) What does 'ref' mean on the link from Particle to Element Declaration ? (Steve) Link from Complex Type Definition to Particle - this can only be to a Model Group subclass (Steve) May want to add the following pointer to make it complete: complex type definition -> (base type) -> complex type definition (Sandy) I know this is probably not needed by DFDL; but may help to include it for completeness. We have it for simple types; may confuse people if it's not on compelx types. (Sandy) UML for DFDL annotations on XSDL: Wondering whether this is necessary. It's a middle step, possibly only useful to implementors (Sandy) 1st bullet - talks about a limitation in the XSDL model - I'd like Sandy to take us through this. MRM carries annotations on groups and group refs.(Steve) 1st bullet - the practical limitation appears to be that you can't override the properties of a global group on a group reference, like you can with elements. Is this going to be an issue? (Steve) 4th bullet - prohibiting dfdl:discriminator on xs:choice seems sensible (Steve) Should "variable definition" be derived from "DFDL annotation base"? (Sandy) The current diagram suggests that "variable definition" can both be part of a format base or as a standalone annotation (outside of a format). Is this true? (Sandy) Can "hidden" be viewed as a specialized element reference? (Sandy) This only implies a "base class" pointer from "hidden" to "element reference". There really isn't much benifit in doing this. It just *feels* better. Don't feel strongly. (Sandy) UML for post-scope resolution and inheritance flattening: Haven't finished reviewing it carefully. (Sandy) Inheritance is used much more often in this diagram. e.g. "Any Element Wildcard" is derived from both "Occurrence Properties" and "DFDL properties Base". Is this intentional? Feels counter-intuitive to me. Components should *have* properties, rather than *be* properties. (Sandy) Wondering whether it makes sense to combine diagrams 2 and 3. That is, a single diagram that has everything inherited/flattered, but don't attempt to remove properties that are not used at runtime. e.g. keep DFDL Schema etc. (Sandy) 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

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Agenda for call today
by Steve Hanson 16 Jan '08

16 Jan '08

Not seen an agenda, I think the following are up for discussion: - Go through last week's minutes - Discuss Geoff & Steves' property precedence - Discuss Mike's UML for DFDL schema subset IBM comments: UML for DFDL subset of XSDL - Need cardinality adding (Steve) - White v black diamond not correct (Suman) - What does 'ref' mean on the link from Particle to Element Declaration ? (Steve) - Link from Complex Type Definition to Particle - this can only be to a Model Group subclass (Steve) - May want to add the following pointer to make it complete: complex type definition -> (base type) -> complex type definition (Sandy) - I know this is probably not needed by DFDL; but may help to include it for completeness. We have it for simple types; may confuse people if it's not on compelx types. (Sandy) UML for DFDL annotations on XSDL - Wondering whether this is necessary. It's a middle step, possibly only useful to implementors (Sandy) - 1st bullet - talks about a limitation in the XSDL model - I'd like Sandy to take us through this. MRM carries annotations on groups and group refs.(Steve) - 1st bullet - the practical limitation appears to be that you can't override the properties of a global group on a group reference, like you can with elements. Is this going to be an issue? (Steve) - 4th bullet - prohibiting dfdl:discriminator on xs:choice seems sensible (Steve) - Should "variable definition" be derived from "DFDL annotation base"? (Sandy) - The current diagram suggests that "variable definition" can both be part of a format base or as a standalone annotation (outside of a format). Is this true? (Sandy) - Can "hidden" be viewed as a specialized element reference? (Sandy) - This only implies a "base class" pointer from "hidden" to "element reference". There really isn't much benifit in doing this. It just *feels* better. Don't feel strongly. (Sandy) UML for post-scope resolution and inheritance flattening - Haven't finished reviewing it carefully. (Sandy) - Inheritance is used much more often in this diagram. e.g. "Any Element Wildcard" is derived from both "Occurrence Properties" and "DFDL properties Base". Is this intentional? Feels counter-intuitive to me. Components should *have* properties, rather than *be* properties. (Sandy) - Wondering whether it makes sense to combine diagrams 2 and 3. That is, a single diagram that has everything inherited/flattered, but don't attempt to remove properties that are not used at runtime. e.g. keep DFDL Schema etc. (Sandy) Regards, Steve Steve Hanson 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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DFDL property precedence - parsing - v1
by Steve Hanson 11 Jan '08

11 Jan '08

Requires FreeMind from http://freemind.sourceforge.net/wiki/index.php/Download Parsing: Writing: tbd Notes: - Precedence is from top to bottom recursively, so the top priority is dfdl:inputValueCalc, then dfdl:byteOrder, then dfdl:encoding, then it's children top to bottom, then dfdl:occursKind (you get the idea). Questions arising: - Does dfdl:escapeScheme apply when dfdl:lengthKind = endOfData ? - Confirm that only signed logical number can have a signed rep, and only unsigned logical number can have an unsigned rep ? (change from spec 028 to 030) - Should dfdl:terminator, dfdl:separator and dfdl:occursSeparator be lists (to handle alternative delimiters) ? (viz dfdl:nullValues) - Why isn't dfdl:nullIndicatorIndex encompassed by dfdl:nullIndicatorPath ? - Use of enum 'xpath' for dfdl:nullKind.? We've used "explicit" elsewhere and decorated syntax to indicate xpath for other properties. For nullKind maybe a better enum would be "external" or "remote" ? - The advanced text delimiter supplement needs revision - most of its content appears to be in the core. Main question is on prefix v infix v postfix separators and how that capability is to be specified. Regards, Steve Steve Hanson 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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Updated spec completion plan
by Steve Hanson 11 Jan '08

11 Jan '08

Alan and I have taken Mike's completion plan and updated it including allocating owners to items. See below. Please say on the next call whether you are able to take on the items allocated to you. MikeB: I'm quite dissatisfied now with the flow of the spec. Everything seems to be needed to describe everything else. E.g., initiators can't be described without describing nulls and default values that they interact with, but those are much later in the spec and involve some very nitpicky properties like nullValueInitiatorPolicy, ..... so all the information about initiators isn't in one place. A big job ahead is revising all the property descriptions to refer to the grammar and the various syntactic regions defined by it. Planned (Roughly) vX+1 - improve (finish?) nulls/default/optionals (Mike - with input from Steve) - 2-level description (schema components) - including UML (Simon) - regular expressions for lengths (Alan) - expression language (Alan) - valueCalc (Mike) - property precedence (Steve) - entities (Alan) - white space handling (Steve) vX+2 - bring supplements up-to-date (Steve) - assertions/discriminators and choice (Suman) - how speculative parsing works (combining choice and variable-occurrence - currently these are separate) (TX person) - reordering the properties discussion (move representation earlier, improve flow of topics) (Alan) vX+3 - escapeSchemes (Ian P) - string xml type (Ian P) - variables (Mike) - selectors (Suman) - improvements on property descriptions (All - split tbd) - envelopes and payloads (Steve) Extraneous to spec - develop Schema for DFDL xsd (Suman) - develop Schema for Schema DFDL Subset xsd (Suman) Regards, Steve Steve Hanson 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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DFDL: Minutes from OGF WG call, 09 Jan 2007
by Ian W Parkinson 10 Jan '08

10 Jan '08

Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 09 Jan 2008 Attendees Mike Beckerle (Oco) Geoff Judd (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Alan Powell (IBM) Steve Hanson (IBM) Suman Kalia (IBM) Agenda 1. OGF 22 in Cambridge, MA 2. Level set on specification drafts 3. Expression Language 4. Nulls and defaults - can we drop useNullForDefault? 5. Other business 1. OGF22 The next OGF conference will be held February 25-29 in Cambridge, MA. As he is local, Mike is planning to attend to represent DFDL. The working group should decide what we would like to present at the conference, if anything, and Mike will enquire upon the closing date for submissions. Could be Jan 11th? 2. Specification Drafts Mike circulated draft 30 of the DFDL specification before Christmas, and had prepared a plan covering the contents of the next three drafts. The objective of the plan was to guide the group to the stage where the specification was not a limiting factor to progress and that implementations could proceed with a reasonable expectation that the specification would not change significantly. Steve mentioned that IBM are attempting to assign remaining workitems internally, and wanted to coordinate this with the other working group members to avoid duplication of effort. Due to the demands of his new role, Mike will need to pass some items that he had been hoping to tackle on to other people. He suggested that editorship of the specification should pass around the group with each draft, ideally to whoever would be making the most significant changes in that draft. For the next draft, number 31, Steve suggested that Alan might be an appropriate editor as he is working on the expression language, which is a key subject for the next draft. Simon would also like to own a draft and would consider this, but that he could not commit in the meeting. 3. Expression Language The group has previously discussed difficulties with forward/backward references in expressions. Mike observed that forward-referencing expressions can occur in a DFDL schema but could only be used during unparse. Discussing whether it is feasible to police this statically, Mike reckoned that while it may be difficult to analyze an expression to see whether it referred forward or not, this would probably be a decidable problem (eg, follow the dfdl:outputValue chain). Steve asked how we should specify the data type to be returned from an expression, there being two candidates: a) the XML Schema type of the DFDL property b) the 'resolved' data type of the DFDL property as needed by the parser Take dfdl:length as an example. The XML Schema type is 'string' because the field can accept numeric literals, expressions, regular expression, etc. But the parser will always want an integer. Agreed that an expression should return the 'resolved' data type. Steve asked whether, in the property descriptions, we should include the allowable return type from an expression. Mike believed that we should, as it may be distinct from the DFDL type for that field. So, the dfdl:length property description in the spec needs to say exactly what the options are - eg, "a literal integer, or an expression that resolves to an integer, or a regular expression that resolves to an integer". Using the XSD "maxOccurs" field as an example, which is normally an integer but may also be the token 'unbounded', Simon suggested that simply using the 'resolved' type may not be sufficient and that a processor will need to be aware that, in some cases, the result of an expression may not be the natural type. Mike concluded that we would need to specify both types as above and also any 'distinguished tokens'. Finally, should a DFDL engine automatically cast an expression result to the 'resolved' type, or instead strictly enforce the return type of the expression. The group felt the latter option to be preferable. (Alan Powell joined the meeting) 4. Nulls and defaults Steve would like to review his previous correspondance with Mike before discussing this further. It will be included in the agenda for next week's meeting. 5. Property Precedence Geoff and Steve have been preparing a proposal for precedence using a mind map. Steve will distribute this initial proposal for wider review. (Mike Beckerle and Suman Kalia left the meeting) 6. Entity references Alan has been looking at the use of XML entity references to more easily allow non-printable characters to be written into DFDL documents, and has distributed a proposal within IBM. There are some issues around this at the moment (need DTD to define entities, allowable characters in XML 1.0 docs). Alan is looking at these. This discussion in IBM had led to the concept of a mechanism to easily represent arbitrary whitespace, which is a common feature of text formats but which causes problems when modelling. Simon has experience with this concept and will send Steve a description of how PolarLake handle this.. Steve suggested we could handle this by allowing delimiters to be a list of allowable values, with the first used as a default on unparse. (We already have this idea for dfdl:nullValue). Simon observed that this could not handle arbitrary length whitespace. Steve said that we should have entities that cover that - like <WSP> and <OWSP> in IBM's WTX parser (the O meaning optional) - these are extremely useful. So then you could say things like (ignore incorrect entity syntax): dfdl:separator ="x0Dx0A x0D" meaning allow the separator to default to CRLF but allow LF on its own. However, Steve also pointed out that in the EDI data format the choice of delimiter comes from an expression, adding to the complexity, because the allowable value of the delimiter is then <value from expression> concatenated with <entity>. Is that supported by current spec?. Eg: dfdl:separator ="{..\delimiter} {..\delimiter}x0Dx0A {..\delimiter}x0D" Simon wondered if we could deal with this situation in a different way by perhaps handling it as 'delimiter padding' and having a DFDL option to allow/trim it. But he cautioned that we must avoid ambiguity - for example, to handle whitespace at the end of a delimiter which is followed by data which allows whitespace. Steve said that in that situation you have no choice but to explictly model the whitespace and not use the arbitrary entities. Geoff thought that if we did go for the trimming approach we may need to describe separate sets of rules for whitespace handling for the markup region and for the data region. Steve will take an action to come up with a proposal. 7. Other business Steve would like to discuss a model of ACORD AL3 length-prefixed data on the working group call, and will add an item to next week's agenda. Mike and Geoff have been corresponding on that. Within IBM, some changes have been proposed to Mike's UML model of DFDL. This will be circulated to the working group when IBM comments are complete. Meeting closed, 17:45 GMT 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

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Agenda for today's DFDL call
by Steve Hanson 09 Jan '08

09 Jan '08

1) OGF 22 in Cambridge, MA Will we participate and if so who will go 2) Level set on spec drafts Mike circulated a proposal Then issued v030 (vNext in the proposal) Assign owners to spec work items in the vX+n drafts 3) Expression language Forward reference limitation - confirm What data type returned by an expression This reveals underlying question, namely a DFDL property has an XML schema type and a 'resolved' type for use by the parser. Eg: dfdl:length is a string in XML Schema terms, but must resolve to an integer ultimately. 4) Nulls and defaults, and whether we can drop useNullValueForDefault 5) ... Regards, Steve Steve Hanson 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: New call in details for Wed call
by Steve Hanson 08 Jan '08

08 Jan '08

Call will take place at usual time. Regards, Steve Steve Hanson WebSphere Message Brokers Hursley, UK Internet: smh(a)uk.ibm.com Phone (+44)/(0) 1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 08/01/2008 17:52 ----- Steve Hanson/UK/IBM 04/01/2008 13:10 To DFDL Working Group cc Subject New call in details for Wed call PARTICIPANT ACCESS INFORMATION: ------------------------------- PARTICIPANT PASSCODE: 8190865 TO JOIN A CONFERENCE 1) You must use a touch-tone phone to participate in an Instant Meeting Conference. 2) Dial the appropriate access number 3) Enter numeric passcode followed by a "#" INSTANT MEETING FEATURES The following Instant Meeting features are available: Press *1 private help menu. Press *3 roll call (private) Press *6 mute or un-mute individual line. Click http://www.mymeetings.com/audioconferencing/globalAccessFAQ.php for information on specific country access dialing. Country Toll Numbers Freephone/Toll Free Number AUSTRIA 43-1-928-9652 BELGIUM 32-2-400-6791 0800-4-9612 DENMARK 45-7014-0237 FRANCE LYON: 33-4-26-69-12-74 080-511-3725 FRANCE MARSEILLE: 33-4-86-06-00-74 080-511-3725 FRANCE PARIS: 33-1-70-70-81-58 080-511-3725 GERMANY 49-69-2222-20363 0800-100-6504 IRELAND 353-1-247-7768 ITALY 39-02-3600-3648 800-985-679 LUXEMBOURG 352-27-000-1312 NETHERLANDS 31-20-713-2741 0800-020-3237 SPAIN 34-91-414-1542 800-099-667 SWEDEN 46-8-566-10-780 SWITZERLAND 41-44-580-3334 0800-000-516 UNITED KINGDOM BIRMINGHAM: 44-121-210-9014 0800-279-9193 UNITED KINGDOM GLASGOW: 44-141-202-3214 0800-279-9193 UNITED KINGDOM LEEDS: 44-113-301-2114 0800-279-9193 UNITED KINGDOM LONDON: 44-20-7019-0808 0800-279-9193 UNITED KINGDOM MANCHESTER: 44-161-601-1414 0800-279-9193 USA 866-505-4412 Restrictions may exist when accessing freephone/toll free numbers using a mobile telephone. Country Freephone numbers cannot be used outside of the country listed. Please provide an International Country toll number to your participants as a back-up in the event of any Freephone restrictions being encountered. ------------------------------------------------------------------------------ Regards, Steve Steve Hanson 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 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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