[DFDL-WG] Material for Call on 2007-10-24

[Alan Powell]

Mike

I have been reviewing ch 6 Sequence Groups, Initiators and Separators  of 
proposal-to-simplify-null-default-optional-handling-v4.doc and I am uneasy 
about the approach of transforming the DFDL. This is because

They are examples rather than rules so do not fully explain the syntax. 
The results are often so convoluted that they do not, at least to me, 
provide any clarification. So much so that  I believe most of the examples 
are actually wrong.

I think that we should either provide proper transformation rules or just 
stick to explaining original DFDL syntax.

Comments added to Ch 6 examples.



Alan Powell

 MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
 Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
 Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898




Mike Beckerle <beckerle at us.ibm.com> 
Sent by: dfdl-wg-bounces at ogf.org
23/10/2007 23:03

To
dfdl-wg at ogf.org
cc

Subject
[DFDL-WG] Material for Call on 2007-10-24







We had been reviewing the facets and default/null/optional a few weeks 
back. 

I said I would make revisions as a number of people had objections. 

Here are documents based on these comments. 


Main things I did: (1) strict adherence to minOccurs and maxOccurs. No 
more notion that these are only for validity checking. 
(2) simple rule for default values: if it's required and there's a default 
value, then use the default value. This is for both input and output. 

I put a bunch of work into illustrating the semantics of things like 
dfdl:separatorPolicy="suppress" and so forth. I had been trying to 
simplify this, but gave up. We're back to 3 policies here: keep, suppress, 
suppressAtEnd. I did figure out a way to express these via DFDL rewriting. 


...mikeb 

Mike Beckerle
STSM, Architect, Scalable Computing
IBM Software Group
Information Platform and Solutions
Westborough, MA 01581
direct: voice and FAX 508-599-7148
assistant: Pam Riordan 
                 priordan at us.ibm.com 
                 508-599-7046
[attachment "proposal-on-facets.doc" deleted by Alan Powell/UK/IBM] 
[attachment "proposal-to-simplify-null-default-optional-handling-v4.doc" 
deleted by Alan Powell/UK/IBM] --
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