SAX2: Should SAXException extend IOException?

David Megginson david at
Thu Dec 23 12:05:36 GMT 1999

Ray Waldin <rwaldin at> writes:

> from David's SAX2 Exceptions proposal:
> > 5. Have all callbacks that formerly threw SAXException throw
> >    IOException instead.  This should help to avoid a lot of exception
> >    tunneling.
> I don't see the point in a Handler throwing an IOException to a
> Parser in most cases.  That is what this item implies, right?  What
> could a DocumentHandler mean by throwing an IOException during a
> call to startElement?  The I/O has already occurred before the
> handler gets involved.

Well, that's really domain-specific.  It could be that a handler in an
XML I/O library does additional I/O (such as retrieving an external
bitmap) which, from the top-level application's point of view, is
still part of the same I/O process.

In the end, though, this is a relatively minor point.  The important
point, for me, is that SAXException extend IOException -- I think that 
it would be convenient to have the callbacks throw IOException rather
than SAXException (otherwise, other IOExceptions will have to tunnel), 
but it's not a show-stopper if everyone else thinks it's a bad idea.

All the best,


David Megginson                 david at

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