xml-dev - A SAX helper class: multiple document handlers

[David Megginson <ak117@freenet.carleton.ca>]

Michael Kay writes:

 > There was discussion during the SAX specification debate of
 > the requirement to notify multiple handlers of the same
 > event.
 > 
 > I have written a simple (trivial!) handler which does this
 > (for document events only) and offer it as a candidate for a
 > standard "helper" class.

Thank you, Michael.  I have had to swat my hand away from the keyboard
over and over again to avoid writing more helper classes myself.  I
think that there is room to write some very exciting stuff on top of
SAX, either in a single large distribution or in several smaller
ones, but I don't think that we should bloat the core distribution any
further.  

It would be interesting, for example, to have a Beans event interface,
like:

  void addStartElementListener (StartElementListener listener);
  void removeStartElementListener (StartElementListener listener);
  void addEndElementListener (EndElementListener listener);
  void removeEndElementListener (EndElementListener listener);

etc.  Programmers could take an invisible XML JavaBean, drag it into a
BeanBox, and connect listeners using the mouse.

Another implementation might allow the user to register objects (or
even methods) to be invoked for specific element types.

SAX is meant to provide the minimal bottom end, with only a couple of
tiny helper classes to avoid excessive confusion among implementors (I
anticipate that the persistence of attribute lists and locators will
quickly become a FAQ); however, I strongly encourage other XML-DEV
members to start creating new, higher-level interfaces that run on top
of SAX, and (if they wish), to collect them into well-packaged
distributions.


All the best,


David

-- 
David Megginson                 ak117@freenet.carleton.ca
Microstar Software Ltd.         dmeggins@microstar.com
      http://home.sprynet.com/sprynet/dmeggins/

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