November 2006 - dfdl-wg - lists.ogf.org

Meeting Notes 2006-11-29
by Westhead, Martin (Martin) 29 Nov '06

29 Nov '06

Present Martin Westhead Geoff Judd Mike Beckerle Discussion * IBM making some progress on next release of a DFDL implementation. Also there should shortly be work on Group semantics from Mike. * Mike reported that Tom Sugden had volunteered to take a rationalization pass at the "syntax" section of the document. * We had a discussion about what it meant to be a DFDL processor and how we should define and talk about parsers that can interpret only a subset of DFDL. Action on Martin to write up the conclusions of this discussion.

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DFDL Telcon tomorrow
by Westhead, Martin (Martin) 28 Nov '06

28 Nov '06

Call Details Time: 9am PDT Number: 1-800-664-0771 At the automated answering system, press 0 for the operator. Ask for the "Daffodil working group" call.

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DFDL Telcon tomorrow
by Westhead, Martin (Martin) 21 Nov '06

21 Nov '06

Call Details Time: 9am PDT Number: 1-800-664-0771 At the automated answering system, press 0 for the operator. Ask for the "Daffodil working group" call.

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OGF DFDL Call minutes for 2006-11-15
by Mike Beckerle 15 Nov '06

15 Nov '06

Tom Sugden and Mike Beckerle participated. Reviewed scoping section that was rewritten by Tom. Decided to add the worked example from the original at the end. Decided to add a section describing the ref attribute at the front. Tom will incorporate minor changes/suggestions which we discussed. Another section of the spec that needs this same rewrite is the syntax section. Tom has agreed to take this on, and will be able to project a date when he thinks it can be done by 2 weeks from today (call of 11/29.) Mike Beckerle STSM, Architect, Scalable Computing IBM Software Group Information Integration Solutions Westborough, MA 01581 voice and FAX 508-599-7148 home/mobile office 508-915-4795

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Scoping Rules Rewrite
by Tom Sugden 15 Nov '06

15 Nov '06

Hi all, Please find attached my attempt at a rewrite of the scoping rules from the draft specification. This work was undertaken in response to concerns about the size of the spec. My aim was to condense the material at the same time as improving clarity. I have certainly reduced the size, so the main question is whether the essentials are still there. My approach was to first try and summarise the rules concisely, making use of tables for easy reference, and then to illustrate them with cut-down examples. I have also created a new set of styles to improve readability, and used a flatter structure for the section. One sub-section from the draft spec was completely cut (and perhaps should not have been): Resolution Rules for Formal Properties. It did not seem to to sit comfortably with the rest of the section since it discusses in detail the logic of a DFDL processor over an entire traversal of a DFDL document. My own feeling is that it would be better in a section of the spec covering the logic of the processor, rather than the rules of the language, or perhaps in a different document. I would be grateful to receive any feedback on this work, and hear opinions about whether a similar approach might benefit other parts of the spec. On the other hand, I will take no offense if you feel the style is inappropriate or the content lacking! It has been a useful personal exercise to learn more about DFDL and spec writing is new to me. All the best, Tom

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Re: [DFDL-WG] DFDL telcon tomorrow
by Westhead, Martin (Martin) 14 Nov '06

14 Nov '06

Sorry folks, I can't make it tomorrow after all. I have just been invited to a meeting to discuss the uses of DFDL within Avaya that clashes directly with our regular telcon. _____ From: dfdl-wg-bounces(a)ogf.org [mailto:dfdl-wg-bounces@ogf.org] On Behalf Of Westhead, Martin (Martin) Sent: Tuesday, November 14, 2006 9:35 AM To: Mailing List for DFDL-WG Subject: [DFDL-WG] DFDL telcon tomorrow Call Details Time: 9am PDT Number: 1-800-664-0771 At the automated answering system, press 0 for the operator. Ask for the "Daffodil working group" call.

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DFDL telcon tomorrow
by Westhead, Martin (Martin) 14 Nov '06

14 Nov '06

Call Details Time: 9am PDT Number: 1-800-664-0771 At the automated answering system, press 0 for the operator. Ask for the "Daffodil working group" call.

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DFDL call tomorrow
by Westhead, Martin (Martin) 08 Nov '06

08 Nov '06

Sorry folks I can't make the call tomorrow. Call Details Time: 9am PDT Number: 1-800-664-0771 At the automated answering system, press 0 for the operator. Ask for the "Daffodil working group" call.

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How to express semantics of unordered groups
by Mike Beckerle 01 Nov '06

01 Nov '06

I'd like to consider this concept as a way to express the semantics in DFDL of unordered groups. The approach is to use source language transformation. Here's an example of an unordered sequence of 2 elements: <xs:element name="n1"> <xs:complexType> <xs:sequence dfdl:unordered='true' separator=","> <xs:element name="s1" type="string" dfdl:initiator="s1:" /> <xs:element name="s2" type="int" dfdl:initiator="s2:"/> </xs:sequence> </xs:complexType> </xs:element> We explain what this means by indicating that it behaves like this rewrite: <xs:element name="n1"> <xs:annotation><xs:appinfo source=....> <dfdl:format validation="cardinality(./s1) <= 1 & cardinality(./s2) <= 1"/> </xs:appinfo></xs:annotation> <xs:complexType> <xs:sequence' separator=","> <xs:choice> <xs:sequence> <xs:element name="s1Initiator" type="xs:string" fixed="s1:"/> <xs:element name="s1" type="xs:string" /> </xs:sequence> <xs:sequence> <xs:element name="s2Initiator" type="xs:string" fixed="s2:"/> <xs:element name="s2" type="xs:int" /> </xs:sequence> <xs:sequence />  </xs:choice> <xs:choice> <xs:sequence> <xs:element name="s1Initiator" type="xs:string" fixed="s1:"/> <xs:element name="s1" type="xs:string" /> </xs:sequence> <xs:sequence> <xs:element name="s2Initiator" type="xs:string" fixed="s2:"/> <xs:element name="s2" type="xs:int" /> </xs:sequence> <xs:sequence />  </xs:choice> </xs:sequence> </xs:complexType> </xs:element> The above is probably missing a DFDL annotation indicating that the discrimination of the choice is done using the s1Initiator and s2Initiator fields based on their parsing correctly w.r.t. their fixed value facet. In XSD, unordered sequences (aka "all" groups) also have the semantics that each element can occur only zero or 1 time. This is modeled by the additional validation constraint you find at the top of the rewritten form. This isn't the only choice for semantics of unordered groups of course, but it is one coherent position on it. I think it is very attractive to reduce the issue of initiator-based unordered sequences to choice and discrimination, since we need those constructs no matter what. Comments? ...mikeb

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