[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: status of "collections" in XPath / XQuery
From: "Michael Kay" <michael.h.kay@n...> > Is there thought going on regarding constraints on collections (when they > are defined)? I may want to have all > invoice numbers in a collection be unique. > > I haven't seen any proposals that address that. Certainly, XML Schema > doesn't provide any cross-document validation. The XLlinkIt validation language at www.xlinkit.com is aimed squarely at this kind of problem, I think. (Christian Nentwich who sometimes posts on this list is, I believe, one of the programmers involved in it.) Schematron can do some kinds of inter-document validation, in particular when there is a link in one document to another, e.g. to a controlled vocabulary. But it lacks a for-each operator, and so is weak for collections. Xpath 2 may help in this, I don't know. I gave up trying to figure out a Schematron expression to do this, but undoubtedly something inefficient based on counting and the document() function could be possible. Cheers Rick Jelliffe
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