multiple handlers

David Megginson ak117 at
Tue Feb 24 18:52:50 GMT 1998

Michael Kay writes:

 > >In a private message, one SAX user raised the issue again of multiple
 > >handlers
 > >Any further thoughts on this issue?
 > >
 > I've implemented a layer on top of SAX that provides not only multiple
 > handlers, but also per-element-type handlers. Since it is trivial to
 > implement this on top of SAX, I suggest it shouldn't go into SAX itself.

I had this same thought when I was walking my girls to school after
lunch.  Unlike a GUI, which spends most of its time waiting for the
user to do something interesting, an XML parser has to deal with
hundreds or thousands of events each second, and perhaps millions of
events in a hefty XML document.  

Upon reflection, I am becoming more inclined to agree with the
arguments that people made in the first round, that the overhead of
walking through a vector of handlers and delivering each event to each
one can be excessive.  Besides, as Michael rightly points out,
implementing a multi-listener interface on top of SAX is trivial if
you really need it.

All the best,


David Megginson                 ak117 at
Microstar Software Ltd.         dmeggins at

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