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Shorthand XPointers can't be streamed

From: Richard Tobin <richard@cogsci.ed.ac.uk>
Date: Fri, 21 Mar 2003 16:01:10 GMT
Message-Id: <200303211601.QAA09723@mcpherson.cogsci.ed.ac.uk>
To: www-xml-linking-comments@w3.org

The fact that an element can be identified by a child that is a
schema-determined ID makes it impossible to search for a match in
a fully streaming manner.

For example, if the <id> element is of schema type ID, then in

  <foo>
   ... millions of child elements ...
   <id>chapter1</id>
  <foo>

a processor that is asked to return the "chapter1" element will have
to buffer the millions of child elements.  Worse, it would have to
buffer them even if <foo> turned out not to have an <id> child with
the right value.

A processor capable of schema type analysis may be able to optimise
this (e.g. an element that does not allow a child that can be of ID
type, and which is known to be valid, cannot have such an ID), but
this requires a lot of work.

-- Richard
Received on Friday, 21 March 2003 11:01:13 UTC

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