xml-dev - RE: Why SAX needs namespace support

[Michael.Kay@icl.com]

Tyler Baker:
> To make this work you would need to do several things:
> 
> (1) Change the ParserFactory class to not return a parser but 
> a ParserGenerator
> object (in this case you might want to change the name 
> "ParserFactory" to "ParserGeneratorFactory").
> 
I do think it would be useful for SAX to include a helper class for parser
selection. This proposal, though, seems a little too abstract for most users
to stomach (like telling someone who wants to watch News at Ten that he
needs to start by instantiating a television factory generator). I'd suggest
something more along the lines of the ParserManager in SAXON (which was
inspired by the ODBC Driver Manager). It currently:

- maintains a list of available parsers, known by familiar product names
(e.g. "xp", "oracle")
- maintains a preference order
- allows an application to load a parser, scanning the preference list till
it finds one suitable.

I've considered for a long time maintaining separate lists of validating and
non-validating parsers so you could choose one from either list: one could
extend this idea to selecting a parser based on all its properties. The
"parser" could also be a composite consisting of a parser plus one or more
filters.

We could then have a simple (static) interface
ParserManager.loadParser(properties) that returns a parser matching the
stated application requirements.

There could also be an interface allowing parsers to register themselves:
ParserManager.registerParser(this); this would call back to get information
about the parser's properties.

I think users could cope with that.

Mike 

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