<br><font size=2 face="sans-serif"><b>Open Grid Forum: Data Format Description
Language Working Group</b></font>
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<br><font size=2 face="sans-serif"><b>Weekly Working Group Conference Call</b></font>
<br><font size=2 face="sans-serif"><b>17:00 GMT, 14 Nov 2007</b></font>
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<br><font size=2 face="sans-serif"><b>Attendees</b></font>
<br><font size=2 face="sans-serif">Geoff Judd (IBM)</font>
<br><font size=2 face="sans-serif">Steve Hanson (IBM)</font>
<br><font size=2 face="sans-serif">Suman Kalia (IBM)</font>
<br><font size=2 face="sans-serif">Simon Parker (PolarLake)</font>
<br><font size=2 face="sans-serif">Ian Parkinson (IBM)</font>
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<br><font size=2 face="sans-serif"><b>Apologies</b></font>
<br><font size=2 face="sans-serif">Mike Beckerle (IBM)</font>
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<br><font size=2 face="sans-serif"><b>1. Information Set Proposal</b></font>
<br><font size=2 face="sans-serif">Following last week's review of the
Information Set proposal, Simon updated the proposal and distributed a
new draft, version 7. Alan queried the reference to empty lists under "No
Value", asking if this was necessary as DFDL does not use a concept
of lists - this is carried over from the XML Information Set specification,
and is only theoretical. The proposal will be distributed wider within
IBM to solicit final comments.</font>
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<br><font size=2 face="sans-serif"><b>2. Review of Revised DFDL Data Grammar</b></font>
<br><font size=2 face="sans-serif">Mike has updated the Data Grammar portion
of the DFDL specification, to take into account the InfoSet proposal, and
distributed this via the DFDL-WG mailing list.</font>
<br>
<br><font size=2 face="sans-serif">The meeting reviewed the revised grammar,
touching upon the following points:</font>
<ol>
<li value=1><font size=2 face="sans-serif">Both the ComplexContent and
ComplexElement productions include a "Prefix" element. Alan asked
whether this duplication was necessary. Steve and Simon noted that this
had not changed during the revision and that there are cases where this
is useful. The meeting agreed not to change this.</font>
<li value=2><font size=2 face="sans-serif">Alan asked why we need both
Element and ComplexContent in the SequenceItem production. Element effectively
introduces a name.</font>
<li value=3><font size=2 face="sans-serif">Simon noted that most of the
changes were in the productions, and wondered what influence the InfoSet
proposal actually had on the specification. Steve said that there had been
real changes, for example with SimpleElement and ComplexElement.</font>
<li value=4><font size=2 face="sans-serif">Steve observed that Prefix and
Postfix Separators no longer appear in the productions table. The meeting
agreed that these were probably no longer necessary, and that this was
a useful simplification, but to check this with Mike.</font></ol>
<br><font size=2 face="sans-serif"><b>3. Object Constraint Language</b></font>
<br><font size=2 face="sans-serif">The UML diagram in the revised InfoSet
proposal uses Object Constraint Language<sup>1</sup> (OCL) to specify an
invariant on the Element class. Simon asked the meeting to consider whether
this might be a useful approach in other sections of the DFDL specification,
in particular when describing parser behaviour. Suman was concerned that
it might prove useful only for specifying parser internals which should
not be covered in the language specification.</font>
<br>
<br><font size=2 face="sans-serif"><b>4. Other Business</b></font>
<ol>
<li value=1><font size=2 face="sans-serif">Suman asked if we need to define
a parser API. Steve suggested that this should not form part of the language
specification, but that there may need to be other specification documents.</font>
<li value=2><font size=2 face="sans-serif">Steve and Alan will be compiling
a list of remaining work items to move the specification towards completion.</font>
<li value=3><font size=2 face="sans-serif">Work has started within IBM,
to attempt to describe a number of industry standard data formats, including
SWIFT and ISO 8583, using DFDL. Simon has a long standing work item to
attempt to describe a number of custom application formats. These efforts
should help validate the utility of DFDL and suggest specification revisions.</font>
<li value=4><font size=2 face="sans-serif">Thanksgiving is next week -
will this affect attendence of next weeks meeting?</font></ol>
<br><font size=2 face="sans-serif"><b>Meeting closed 17:35 GMT</b></font>
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<br><font size=2 face="sans-serif"><b>Actions</b></font>
<ol>
<li value=1><font size=2 face="sans-serif">Mike to comment on the omission
of initial prefix Separators and final postfix Separators from the productions
table, in the revised DFDL Data Grammar. Are these intended to be covered
by other elements in the productions, or do they need to be added?</font></ol>
<br><font size=2 face="sans-serif"><b>References</b></font>
<ol>
<li value=1><font size=2 face="sans-serif">Object Constraint Language;
specification at http://www.omg.org/technology/documents/formal/ocl.htm</font></ol>
<br>
<br><font size=2 face="sans-serif"><br>
Ian Parkinson<br>
WebSphere ESB Development<br>
Mail Point 211, Hursley Park, Hursley, Winchester, SO21 2JN, UK</font><font size=3 face="sans-serif"><br>
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