[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Best Practice: id-idref or external entities?
Entities, I have no opinions about. They get resolved before the XML Data Model (XDM) comes into the picture for XQuery/XSLT processing. The problem is with id/idrefs and their combination with XQuery/XSLT/Xpath set of specifications. Examples: 1. nodes in XDM have an abstract unique identifier 2. this should NOT be confused with the @id attribute 3. the abstract identifier is unique across a universe that is NOT defined by the XDM, while the @id is unique on a document level 4. the abstract identifier is not serializable by default (it might in some implementations), while the @id obviously is 5. it is not clear to me how the @id/@idref non dangling pointers, aka @idrefs pointing nowwhere, is maintained through XQuery Updates (if at all) in case of general XML databases which do not consider “documents” a first class citizen. Etc, etc, etc. Id/idrefs and XDMs have been orthogonal in their design since the beginning, and it is better not to tempt the devil in this fragile area. It might become a source of nasty bugs, depending on the implementation. Hope that helps, Dana > On Oct 8, 2015, at 7:34 AM, David Carlisle <d.p.carlisle@gmail.com> wrote: > > On 8 October 2015 at 13:10, Daniela Florescu <dflorescu@mac.com> wrote: >> My personal point of view would be very simple to express: avoid them if you can. >> >> They mix very badly with XQuery and co. >> >> Best regards >> Dana > > I'm not sure if you mean avoid entities here, or avoid id references? > > Both have good and bad aspects with respect to XQuery/XSLT processing > it seems to me. > > We use entities (internal rather than external mostly, but that's not > really relevant here) a lot precisely because they are transparent to > the XSLT/Xquery processing. > > To follow id/idrefs (or xlink or any custom link like xhtml href) > requires more code at the XSLT level, although they typically help > manage other properties such as uniqueness, so as usual, the answer > depends on what you want to do....:-) > > David
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