SAX: do we want a base class

David Megginson ak117 at
Sat Jan 3 18:44:28 GMT 1998

David Ornstein writes:

 > My point is about a relationship: as the usefulness of the base
 > class climbs towards necessity, the probability of people using
 > SAX-implementing parsers *that don't come with the base class
 > supplied* declines.  This is only important iff the design of the
 > API is influenced by the assumption of the presence of the base
 > class.  Some of the "design issue" posts seemed to me to be heading
 > in that direction.  If we divide the world into SAX implementors
 > and SAX clients, I think that the base class is a useful thing for
 > *clients* to build and use; it's how I'd do it.  As such, I think
 > it probably doesn't belong on the implementor side of the line.

I should clarify: the SAX interfaces and the XmlAppBase base class
will be written only once for each programming language, and they will
live in their own package (in languages that use packages).
XmlAppBase will depend only on the interfaces for information -- in
other words, there will be no such thing as a SAX-implementing parser
without the base class (parser writers need not be concerned with the
base class at all).

In Java, for example, there would be three class files in the SAX
package (I'll deal with naming and packaging in a later posting):

  XmlParser.class	The interface for a SAX-aware parser
  XmlApplication.class	The interface for an object with event
  XmlAppBase.class	A base class for an object with event handlers.

All Java-based XML parsers that use SAX will refer to this package,
and all will have these three class files available in the same
location.  The same would apply to C++ headers, etc.  I expect that in
Java XmlAppBase.class will weigh in at under 2K (perhaps far under).

All the best,


David Megginson                 ak117 at
Microstar Software Ltd.         dmeggins at

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