On Tue, 6 Sep 2005, Mike Beckerle wrote:
(2) is trickier. I suggest a proposal for pointers in DFDL should begin with an analysis of the approaches to pointers in XML and XSD, in particular
ID, IDREF - in basic XML These are only used in attributes, they point to named entities.
unique, key, keyref - that is, what XSD calls "Identity Constraints" These operate on Xpaths.
I'd like to see annotations to unique, key, and keyref allowing these logical XSD concepts to be mapped into addresses and pointers within the data.
So how would this work? I'm thinking of something like a list (index). A C data structure is something like: struct thing { struct thing * next; struct blob payload; } In the file, there are a bunch (not necessarily contiguous!) records, with a pointer to the next one and a blob. next -> next -> NULL blob1 blob2 How would you want to describe this data?