OGF DFDL WG minutes 2007-12-05 call Suman Kalia, Simon Parker, Alan Powell, Mike Beckerle (who else? - was someone else on also) We discussed Output issues in the DFDL expression language: E.g.., an outputValueCalc for a field in the header of a data stream may contain information that requires you to know the rep, or length of the rep, of the whole data item. We concluded that this kind of thing can't be ruled out. Some formats just require buffering and are not streamable; however, implementations can vary on just how large a data item they're able to cope with here. Expression language section will include a subsection highlighting this issue and that implementations can vary here. Alan will update his expression language proposal and include this. Also suggested was a path length-from-to function that takes 2 path expressions and gives you the size of the represntation between them. (start of first, to last bit before start of 2nd). (I don't think we discussed a clear use case motivating this, but there may be one. We did discuss applications trying to fit data into limited size boxes, but the use case is not clear. Also note that all representation lengths are subject to change due to different starting alignments.) Nillable and Default: We also discussed the interaction of nillable and having a default. The sense of the group on the call is that we can restrict these so that if something is nillable it cannot also have a default value, and that the behavior of DFDL on output for a required element that is nillable but not in the logical data, is to create a null value. Everyone agreed that there is no need for a property useNullValueForDefault because this should always be the behavior. Mike will forward a proposal. ...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@us.ibm.com 508-599-7046