[DFDL-WG] Fw: OGF DFDL WG call today 23-01-2008 - agenda

[Alan Powell]

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

----- Forwarded by Alan Powell/UK/IBM on 23/01/2008 17:18 -----

Alan Powell/UK/IBM 
23/01/2008 12:08

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Subject
OGF DFDL WG call today 23-01-2008 - agenda





Review items from previous calls.

-  OGF22

-  Specification  drafts

-  Expression language


- Property precedence

- UML for DFDL schema


Discussion for this call

-  Review entity proposal

-  Steve's suggestions
 1)  This is related to the white space discussion around entities. One 
way to handle the situation where the terminator can vary is to allow the 
DFDL markup properties (dfdl:terminator, dfdl:separator, etc) to be lists, 
just like we already do for dfdl:nullValues. (IBM's WTX has this 
capability). 

2) We've allowed the prefix of a prefixed length to be explicitly 
described as a non-event field using dfdl:lengthPrefixType. Should we 
permit this for markup properties?  Instead of supplying a list of 
possible values, you supply a simple type with enums for the values. This 
could be viewed as an alternative/complementary to 1). There is a 
limitations - because we are using XSDL enumeration facet, we are 
constrained by its syntax so I don't see how we could use our own entity 
scheme or expressions. Also, I suspect that enums are inherently unordered 
so we'd need a way of saying which to use on output (use an element of 
simple type and use XSDL default attribute?).  Lastly, we should not force 
a user to model an initiator as an element/type - most users just see it 
as a piece of text so just entering the value must still be allowed. 

3) Let's say my delimiter is dynamically defined at the start of the data, 
like EDI allows. We would handle that in DFDL using an expression or 
variable. However, EDI also allows random white space to appear after the 
delimiter. Can our expression/entity syntaxes handle this?  Does this 
preclude use of 1) or 2)? 



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






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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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