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

DFDL: Minutes from OGF WG call, 13 Feb 2008
by Ian W Parkinson 14 Feb '08

14 Feb '08

Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 13 Feb 2008 Attendees Mike Beckerle (Oco) Steve Hanson (IBM) Suman Kalia (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Apologies Alan Powell (IBM) 1. Specification Draft Status Alan has distributed draft 31 of the DFDL specification. The meeting reviewed the plan for the next few versions of the drafts and updated it to reflect progress and revised target dates - a copy of the updated plan is attached to these minutes. Simon's UML diagrams describing the schema components are now planned for inclusion in draft 32 but require further discussion. This discussion will be added to the agenda for the DFDL-WG call on 27th February, but Simon would appreciate comments via e-mail before then. These diagrams are intended to set a conceptual model for DFDL and to show where annotations may be attached, but will not be used more formally, e.g. to automatiically generate APIs. The work on nulls/defaults/optionals is complete, except for some small details, which will be included in draft 32. The 'valueCalc' work has been progressed but is not complete, and is also now targeted for draft 32. Other items originally planned for draft 31 are complete and have been included in the draft. 2. Assertions, Discriminators and Choice Suman has distributed an example showing the use of discriminators in choice constructs in DFDL schemas. The meeting discussed the distinction between discriminators and assertions - Mike described an assertion as simply a predicate which, if encountered within a choice, can cause backtracking. In contrast a succesful discriminator expression would lock the choice into a particular branch. If no discriminator matches, then the parse would fail - unless, as Simon pointed out, the choice itself was optional. Simon also suggested that the last branch of a choice could be left without a discriminator to act a a catch-all, but felt that the purpose of a discriminator should be more to help disambiguate between the possible branches rather than form such a "swtich" construct. Steve asked about the timing attribute on assertions, and in particular whether we'd need a similar attribute for discriminators. Mike suggested that the timing attribute might have been included simply to make implementation easier; as without it an implementation would need to perform a significant amount of static analysis. The motivation for discriminators was to allow a choice to be resolved by data encountered before the choice. However as Steve and Suman thought there were use cases where a discriminator might need to refer to elements inside the choice, and so a timing option would be useful. Suman will prepare such an example, and Mike will schedule a further discussion of this topic. Simon distributed an alternative example, showing the use of fixed fields instead of discriminators or assertions., which he felt might form a useful starting point for a full description of choice disambiguation. (Steve left the meeting) 3. Presentation for next OGF conference Simon suggested that Mike highlight the recent discussion topics of the working group, and items which have recently been added to the specification, and asked whether it would be useful to include the UML diagrams. Mike would like to display the diagrams and see whether they trigger a discussion amongst the delegates. He would also like to present work on variable markup and valueCalc. Meeting closed, 18:00 GMT Attachment: revised plan for specification drafts Draft 31: Improve (finish?) nulls/defaults/optionals (Mike, with input from Steve) - Done, apart from minor edit task Expression language (Alan) - Done Property precedence for parsing (Steve) - Done Entities, including basic white space (Alan) - Done Draft 32 ("vX+2"): valueCalc (Mike) - Feb 27, 2008 Remaining aspects of null/default/optionals (Alan) - Mar 5, 2008 2-level description of schema components, including UML (Simon) - Feb 27, 2008 Property precedence for writing (Steve) - Feb 15, 2008 Variable markup (Steve) - Feb 29, 2008 Regular expressions for lengths (Alan) Bring supplements up-to-date (Steve) - Mar 7, 2008 Assertions, discriminators and choice, including discussion of timing option (Suman) - Feb 19, 2008 How speculative parsing works (combining choice and variable-occurence - currently these are separate) (TX person) Reordering the properties discussion: move representation earlier, improve flow of topics (Alan) Draft 33: ("vX+3"): Escape schemes (Ian P) - Mar 21, 2008 String XML type (Ian P) - Mar 21, 2008 Variables (Mike) Selectors (Suman) - Mar 3, 2008 Improvements on property descriptions (All - split TBD) Envelopes and Payloads (Steve) - Mar 5, 2008 Extraneous to spec: Develop Schema for DFDL xsd (Suman) - Mar 15, 2008 Develop Schema for Schema DFDL Subset xsd (Suman) - Mar 30, 2008 (might not be needed) 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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Fw: Agenda for call 2007-02-13
by Suman Kalia 13 Feb '08

13 Feb '08

Action Item for Vx+2 : - assertions/discriminators and choice (Suman) Attached is an example of how discriminators can be used in DFDL to identify a particular branch within choice.. <?xml version="1.0" encoding="UTF-8"?> <xsd:schema targetNamespace="http://www.example.org/choiceDiscriminators" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:dfdl=" http://dataformat.org/" xmlns:tns="http://www.example.org/choiceDiscriminators"> <xsd:element name="multiRecord" type="tns:MultiRecordType"></ xsd:element> <xsd:complexType name="MultiRecordType"> <xsd:sequence> <xsd:element name="recordType" type="xsd:string" ></xsd:element>  <xsd:choice> <xsd:sequence> <xsd:annotation> <xsd:appinfo source=" http://dataformat.org/">  < dfdl:discriminator test="..\recordType='name'" />  </xsd:appinfo> </xsd:annotation> <xsd:element name="firstName" type ="xsd:string" /> <xsd:element name="lastName" type= "xsd:string" /> </xsd:sequence> <xsd:sequence> <xsd:annotation> <xsd:appinfo source=" http://dataformat.org/"> < dfdl:discriminator test="..\recordType='addr'" />  </xsd:appinfo> </xsd:annotation> <xsd:element name="streetAddr" type="xsd:string" /> <xsd:element name="city" type= "xsd:string" /> <xsd:element name="state" type= "xsd:string" /> <xsd:element name="zip" type= "xsd:string" /> </xsd:sequence> <xsd:element name="otherElem" type= "xsd:string"> <xsd:annotation> <xsd:appinfo source=" http://dataformat.org/"> < dfdl:discriminator test="..\recordType='oth" />  </xsd:appinfo> </xsd:annotation> </xsd:element> </xsd:choice> </xsd:sequence> </xsd:complexType> </xsd:schema> Suman Kalia IBM Toronto Lab WebSphere Business Integration Application Connectivity Tools Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia(a)ca.ibm.com ----- Forwarded by Suman Kalia/Toronto/IBM on 02/12/2008 06:59 PM ----- "Mike Beckerle" <mbeckerle.dfdl(a)gmail.com> Sent by: dfdl-wg-bounces(a)ogf.org 02/12/2008 06:24 PM To <dfdl-wg(a)ogf.org> cc Subject [DFDL-WG] Agenda for call 2007-02-13 Topics for this call include – · Content for OGF22 Meeting. – I need to know what features of our progress we want to highlight. The section about status and progress is where this content goes. Slides 37 through 51 of the OGF21 deck, which is here: http://forge.ogf.org/sf/go/doc15029?nav=1 · Comments on Draft 031 · Review of next tasks Old task list below for reference: Planned (Roughly) vX+1 - 2-level description (schema components) - including UML (Simon) - regular expressions for lengths (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) -- dfdl-wg mailing list dfdl-wg(a)ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg

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Agenda for call 2007-02-13
by Mike Beckerle 12 Feb '08

12 Feb '08

Topics for this call include - . Content for OGF22 Meeting. - I need to know what features of our progress we want to highlight. The section about status and progress is where this content goes. Slides 37 through 51 of the OGF21 deck, which is here: http://forge.ogf.org/sf/go/doc15029?nav=1 . Comments on Draft 031 . Review of next tasks Old task list below for reference: Planned (Roughly) vX+1 - 2-level description (schema components) - including UML (Simon) - regular expressions for lengths (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)

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ogf-dfdl-v1.0-Core-031.doc
by Steve Hanson 08 Feb '08

08 Feb '08

Draft 031 of spec is posted to GridForge here http://forge.gridforum.org/sf/go/doc15032?nav=1 Content as below: 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 08/02/2008 14:26 ----- Alan Powell/UK/IBM 07/02/2008 17:19 To Steve Hanson/UK/IBM@IBMGB cc Geoff Judd/UK/IBM@IBMGB Subject ogf-dfdl-v1.0-Core-031.doc Steve The following updates have been made in this version Rewrite expression language section Update calculated values Added entities instead of hex escape Added parsing property precedence Added most of the clarifications around defaults, nulls and empty strings I was unable to add the DFDL UML diagrams due to lack of time. These will be done in the next version. Thanks 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: Minutes from OGF WG call, 06 Feb 2008
by Ian W Parkinson 07 Feb '08

07 Feb '08

Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 06 Feb 2008 Attendees Steve Hanson (IBM) Geoff Judd (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Alan Powell (IBM) Apologies Mike Beckerle (Oco) Suman Kalia (IBM) 1. Review of the draft DFDL Schema Abstract Model Simon has distributed, via the DFDL working group mailing list, a draft of the UML description of the DFDL schema components, with diagrams built from scratch but using concepts from a number of different, public, UML descriptions of XML schema. The meeting reviewed and discussed this draft. 'Particle' diagram Steve noted that the diagram has changed some of the object names. Simon agreed that he expected some of these to revert to standard XML nomenclature - but that some concepts don't have an existing naming convention. The diagram allows for "all" groups - which are not supported in DFDL. This is as specified in section 5.1 of the present DFDL specification draft. The diagram shows "Group" as a subclass of "GroupDefinition". The XML schema specification does appear to allow this, but the meeting agreed this should be removed from the diagram. Steve and Geoff suggested that GlobalElement should be modelled as a subclass of ElementDeclaration. 'Type' diagram The diagram distinguishes between GlobalType and TypeDefinition, to allow GlobalTypes to be named while TypeDefinitions remain anonymous. The 'base' relationship should be between TypeReference and SimpleType, not between TypeReference and TypeDefinition. Complex type inheritence is not allowed by DFDL. After consulting the schema specification, Steve withdrew his suggestion that ComplexType should contain a ModelGroup rather than a Particle. Simon pointed out that XML Schema 1.1 will allow particles to take annotations, which may prove useful for DFDL. 'DFDL Annotations' diagram Hidden elements are wrapped inside DFDL annotations. This allows for a DFDL schema to be mapped to an XSD schema by stripping all DFDL annotations; the resulting XSD schema describing a DFDL InfoSet for the DFDL schema. This is a goal of DFDL. Alan asked about the purpose of these digrams. They are intended to model and communicate the valid subset of XML schema, and also show where DFDL annotations can be placed in a DFDL schema. We could also use these diagrams to model which XSD objects each DFDL property affects, as well as showing where the properties may be defined - however Simon felt that as a property is not itself a DFDL annotation, this information is better documented elsewhere. Steve felt that the diagrams included in this draft are overcomplicated, and wondered if we could reduce the number of boxes in the diagrams, for example by removing the distinction between named and anonymous objects. Simon observed that this is an important distinction for DFDL as, for example, named types may be reused in different contexts, and this distinction allows us to describe how properties apply differently to named and anonymous types. With this in mind, the diagrams are as simple as possible. 2. Other business Alan will incorporate the UML diagrams, along with the other planned specification updates, into a new draft of the specification to be distributed on the 7th Feb. Meeting closed, 18:00 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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Re: [DFDL-WG] Action 14: Propose DFDL entity scheme v5
by Alan Powell 07 Feb '08

07 Feb '08

All Latest proposal incorporating comments One question: should DFDL support standard XML entities? I have always assumed so but it is not listed in supported XML schema functions. 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 Ian W Parkinson/UK/IBM 22/01/2008 15:29 To Alan Powell/UK/IBM@IBMGB cc DFDL-Technical-Core@IBMGB, dfdl-wg(a)ogf.org, "Mike Beckerle" <mbeckerle(a)OCO-INC.COM> Subject Re: [DFDL-WG] Action 14: Propose DFDL entity scheme Hi guys, For reference, and from wikipedia (search "newline"): "The Unicode standard addresses the problem by defining a large number of characters that conforming applications should recognize as line terminators: LF: Line Feed, U+000A CR: Carriage Return, U+000D CR+LF: CR followed by LF, U+000D followed by U+000A NEL: Next Line, U+0085 FF: Form Feed, U+000C LS: Line Separator, U+2028 PS: Paragraph Separator, U+2029" ... so I guess, during parse, any of these sequences should match %NL; (maybe excluding FF and PS as being more significant than a single new line?). I agree with Mike, for unparse we'd presumably need a new property to specify this. Again, from wikipedia, this time regarding whitespace: "In Unicode (Unicode Character Database) the following codepoints are defined as whitespace: U0009-U000D (Control characters, containing TAB, CR and LF) U0020 SPACE U0085 NEL U00A0 NBSP U1680 OGHAM SPACE MARK U180E MONGOLIAN VOWEL SEPARATOR U2000-U200A (different sorts of spaces) U2028 LSP U2029 PSP U202F NARROW NBSP U205F MEDIUM MATHEMATICAL SPACE U3000 IDEOGRAPHIC SPACE" ....so presumably &WSP; would match any of these characters on parse. What should it generate on unparse? Cheers, Ian Ian Parkinson WebSphere ESB Development Mail Point 211, Hursley Park, Hursley, Winchester, SO21 2JN, UK From: Alan Powell/UK/IBM@IBMGB To: "Mike Beckerle" <mbeckerle(a)OCO-INC.COM> Cc: dfdl-wg(a)ogf.org, DFDL-Technical-Core%IBMGB(a)uk.ibm.com Date: 22/01/2008 14:41 Subject: Re: [DFDL-WG] Action 14: Propose DFDL entity scheme Hi Mike %NL; is a single character <LF> on those target platforms where that is the convention or <CR><LF> on others, etc. This is intended to make it easier for the same dfdl schema to parse messages from different platforms. I know we avoided target platform in DFDL and was expecting that this would cause some debate. This will be a good discussion for tomorrow's call 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 "Mike Beckerle" <mbeckerle(a)OCO-INC.COM> 22/01/2008 13:29 To Alan Powell/UK/IBM@IBMGB, <DFDL-Technical-Core%IBMGB(a)uk.ibm.com>, <dfdl-wg(a)ogf.org> cc Subject RE: [DFDL-WG] Action 14: Propose DFDL entity scheme Is the &NL; supposed to represent a single character? Or can it be a CRLF? There?s no notion of ?the target platform? in DFDL. We?ve specifically avoided this notion on purpose. So we need a separate property like newline=?&CR;&LF;? or newline=?&LF;? if we want &NL; to be meaningful, unless some other property is suitable. There are some other Unicode whitespace and Unicode line-ending characters. Do we want to include those in the definitions of WSP and NL ? I recall there are 4 line-endings in Unicode. ?mikeb From: dfdl-wg-bounces(a)ogf.org [mailto:dfdl-wg-bounces@ogf.org] On Behalf Of Alan Powell Sent: Tuesday, January 22, 2008 6:32 AM To: DFDL-Technical-Core%IBMGB(a)uk.ibm.com; dfdl-wg(a)ogf.org Subject: Re: [DFDL-WG] Action 14: Propose DFDL entity scheme All Attached is the latest proposal for DFDL 'entities' The main changes are: - No longer using XML entities as this proved to not meet all the requirements - New generic mnemonics for <NL> and others to represent the NL on the target platform. 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 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 -- 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

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DFDL expression language
by Alan Powell 06 Feb '08

06 Feb '08

All Latest version of the dfdl expression language. As a result of the comment received I have added a section with a formal description of the syntax and removed the equivalent word sections. The syntax was extracted from the XPath spec and unnecessary sections removed. This doc has been included in the latest version of the full spec. 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: mikeb unable to make call this week
by Mike Beckerle 06 Feb '08

06 Feb '08

Sorry folks, I did work with Steve on nulls/defaults, and that's in to Alan for integration I believe (yes steve?) I also did my work reviewing the expression language draft. I tried to write the calculated elements (inputValueCalc &c) section. Small improvements sent to alan, but there's more to do here still. I need the slides from the last OGF to prepare for the one here in Cambridge MA later in Feb. I am registered now. .mikeb

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DFDL: Minutes from OGF WG call, 30 Jan 2007
by Ian W Parkinson 01 Feb '08

01 Feb '08

All, Here are the minutes from Wednesday's meeting - apologies for the delay. As ever please let me know of any corrections. Cheers, Ian Open Grid Forum: Data Format Description Language Working Group Weekly Working Group Conference Call 17:00 GMT, 30 Jan 2008 Attendees Mike Beckerle (Oco) Steve Hanson (IBM) Geoff Judd (IBM) Suman Kalia (IBM) Simon Parker (PolarLake) Ian Parkinson (IBM) Alan Powell (IBM) 1. Specification drafts Alan has not yet received any updates for the next draft of the specification, which is due soon. As Alan is on vacation from the end of next week, he is looking for input as soon as possible. The group recorded the following status for items targetting for the next specification draft: Nulls/default/optionals - Mike and Steve will collaborate on this and hope to have a draft ready for the end of next week. Description of schema components - Simon expects to have this ready by the end of the week.. Regular expressions for lengths - This is now targeted for the following specification draft ("vX+2") Expression language - Alan has distributed a new draft for review and has asked for comments. Mike will review this next week. valueCalc - Mike will write up at least a first draft, and aims to have this ready for next week. Property precedence - Steve is looking for review comments on the previously distributed mindmap. The specification can include this information simply as a list, not as a "mindmap" tree. It may be useful to combine this information with the schema components diagram. The present proposal only handles parsing; Steve will extend this to cover unparsing. Entities - The group has been having good discussions regarding the entities proposal. White space handling - Whitespace seems to be largely handled by the entities proposal. Steve has been thinking about a way to introduce variable terminators to DFDL, which is discussed later in the meeting. 2. Expression Language Alan distributed a new draft of the expression language proposal, and thanks Simon for his comments. As noted above, Mike will send review comments next week. The second part of the proposal document is text from the current specification draft, which will be replaced by the new proposal. This is included for "history" and is not intended to be reviewed. 3. Whitespace The MIME header format allows for optional whitespace either side of a colon used to delimit the header name and its value. Steve felt that this justfied the need for the proposed %OWSP; entity (along with the %WSP; entity). Mike wondered whether this lead to a slippery slope where we try to handle other complex delimiters similarly, for example, case-insensitive delimiters. Steve would like to propose a more general way to handle complex delimiters in DFDL. Mike would have no objection to having both %WSP; and %OWSP; in the language if these could be described in terms of Steve's more general approach. In PolarLake, the MIME header use case would be handled using a name field (terminated by a colon), with a optional field between the colon and the value which would consume any whitespace. 4. Recursive definitions for delimeters Steve has proposed describing initiators in terms of named types. For example, an intiator could be defined using a simple enumeration type to list its possible values, or one using a pattern facet or assertions. This would extend DFDL's current use of such facets, which are presently used only for validation. Mike distinguished between 'format' and 'content' data, and suggested that this conceptually means that we can interpret facets during parsing for format data, but only at validation for content. Simon suggested a similar concept of "system data" vs. "user data". We would need to revisit speculative parsing to deal with this issue. An alternative, suggested by Simon, would be to relax the present restriction which allows an expression to only return one value. If an expression could return a sequence of values, as is allowed by XPath, then we could use expressions to describe delimiters with multiple possible values. On output, a DFDL unparser would write out the first value in the sequence. Mike observed that such a scheme would solve the 'quoting hell' problem present with simple, space-delimited, XML lists as presently allowed for the nullValues property. If we adopt Steve's approach, we may not be able to access DFDL constructs (variables, expressions or entities) in facets. Steve pointed out that XSD processors would typically reject an enumerated type, restricted to length 1, where the enumeration includes a DFDL entity - the XSD processor will not recognise the DFDL entity and instead treat this as a string of length greater than 1. Alan asked whether there are any dynamic cases, where the set of terminators is obtained from the document itself. Mike felt that this could be modelled using assertions, though this would leave terminator on output undefined; and that a solution where complex types may be used as terminators would probably allow us to handle most of these cases. Steve mentioned the EDI format, which allows a document-specified delimiter to be used with optional whitespace. How, asked Simon, should we handle the output value of a complex delimiter? This must come either from the DFDL schema or from the infoset. Steve suggested we use default properties in the subelements of the type, and Mike suggested we could similarly use outputValueCalc. Steve and Mike agreed that a terminator wouldn't be present in the infoset, by analogy to the similar mechanism used for length prefixes. Further, this mechanism might allow us to remove a number of properties related to terminators. Although Steve had intended this mechanism to be used with simple types or elements, Mike and Suman thought it would be appropriate to allow complex types. Elements would allow the use of the 'default' attribute for use on output. Mike contrasted this to the prefix length solution, where a simple type is used: the value under prefix length is treated as an integer, so it is appropriate to handle it as such. Here, however, we are modelling syntactic constructs. Simon felt that users will think in terms of elements. Steve will prepare some examples and a proposal for inclusion in the "vX+2" draft. 5. Other business Simon will email the group with some questions about the UML schema components description. Meeting closed, 18:10 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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