[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Why SAX needs namespace support
At 12:19 PM 1/26/99 -0500, Tyler Baker wrote: >Implementing namespaces in an XML parser is a trivial task, but dealing with >namespaces at the application level is a totally different story, >especially with this namespaces scoping stuff. How do you deal with >namespaces in the DOM? I don't expect to convince Tyler Baker that namespaces are anything but an alien conspiracy, but I don't think it would be proper to ignore his repeated assertions that namespace *scoping* somehow makes processing more difficult. The scoping is purely a syntactic mechanism in the XML document that can't possibly have any effect at the DOM level. The following two documents are namespace-equivalent: <a xmlns:A='http://a.b.c'> | <a xmlns:A='http://a.b.c' | xmlns:X='http://x.y.z'> <b xmlns='http://a.b.c'> | <A:b> <c/> | <A:c/> </b> | </A:b> <d xmlns='http://z.y.z'> | <X:d> <A:e></A:e> | <A:e></A:e> </d> | </X:d> </a> | </a> A namespace-aware parser, such as expat, makes this clear, allowing you to ascertain that the element whose type is "e" is in the namespace http://a.b.c. True, the DOM is going to have to do something about this, as in add one more method per element and attribute to store/update its namespace. But what on earth makes anyone think that namespaces would be scoped in the DOM? The scoping in XML files is purely a syntactic minimization technique. I.e., if I have a DOM tree modelling the document above (surely everyone agrees that I get the same DOM tree from both instances) and I go stick a new "f" element as a child of the 'e' element, surely it makes no sense to put it in the either the a.b.c or x.y.z namespaces auto-magically. Among other things, it might come from some entirely different namespace. To put this another way, namespaces are merely a syntactic mechanism to allow each element type and attribute name in a document to be qualified by some URI. The DOM should obviously preserve this information, but I can't see why it should be concerned with the syntactic sugar that was used to express it. -Tim xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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