SAX: Entity Resolution

Paul Prescod papresco at
Mon Jan 5 11:07:56 GMT 1998

David Megginson wrote:
> -----------------
> While I agree that a full entity manager would be more powerful than a
> simple callback, I am not certain that the power will really be needed
> by most SAX users; furthermore, if it is needed, that functionality
> can be supplied more generally by an HTTP or FTP proxy server.  For
> now, then, I recommend that we stick with the resolveEntity callback,
> which is simple to use and to learn, but provides 80% of the required
> functionality (that's 80% in the abstract 80/20 sense).

I agree with James on this one. I think that the entity manager
interface is actually simpler in several senses:

#1. It more perfectly allows you to ignore entities if you don't care
about them. Think of the difference between 1.0 AWT and 1.1 AWT event
handling. In the former you implement certain callbacks to get certain
behaviour. In the latter, you register callbacks.

In the old-style interface, it was only possible to make a simple applet
that ignored most events by using the magic of inheritance (which we
should not depend on too heavily). In the new-style interface you can
ignore a particular object's events by merely not registering a handler
for them. I contend that the latter is simpler in the case where you
don't care about the events.

#2. It more perfectly aligns with the language and intent of the SGML
spec. where an entity handler is a distinct and important code module.
XML-Lang does not specify the concept of an entity handler, but those of
us from the SGML world know it to be a useful organizing concept and I
think we can help the XML new-comers by promoting it.

#3. The role of the XML App is not to provide information, but to
consume it. I think that mixing up these responsibilities is confusing
and complicates the construction of XML Apps.

Art is always at peril in universities, where there are so many people, 
young and old, who love art less than argument, and dote upon a text 
that provides the nutritious pemmican on which scholars love to chew. 
				-- Robertson Davies in "The Cunning Man"

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