xml-dev - RE: ModSAX (SAX 1.1) Proposal

["Ingargiola, Tito" <ti64877@imcnam.sbi.com>]

Hello,

Thank you for your response and the example you provided.  The rationale you
provide for having a marker interface is good in that it provides full
generality -- *any* kind of handler can be attached to the parser to do
*any* kind of thing.  Ok.  My feeling is that while there may be a slew of
PingHandler -like handlers which will do who-knows-what, there will also be
a (more common and useful!) set of *Handlers which will do the same kind of
things; it would be unfortunate if handlers which did the same work (e.g.,
validation) had different interfaces simply because no structure was
provided for the implementors to follow.  (Will J Clark's validation handler
have the same interface as IBM's?  unlikely.  Will they be interchangeable?
-- iff my parser knows about both of them...).

I see two ways around this difficulty.  The first is to define a set of
subinterfaces of ModHandler which are adapted for particular uses.  This way
we have a shared known set of  Handlers for our most common uses.  Another
means to the same end is to have a mechanism by which a parser can lookup
(perhaps using the URI mechanism you and D. Brickley have been discussing)
specific types of *ModHandlers.  Thus a parser can learn about a particular
kind of handler on the fly.  Both approaches have limitations, I know.  The
first is difficult because it's hard to define those interfaces a priori.
The second, at least looking at CORBA's Dynamic Invocation mechanism as an
example, tends to be overly complex and messy.  For these reasons, I could
certainly see deciding against them, leading us back to (something like)
what you proposed originally...  but it seems to me both possible and
desirable to provide *some* structure in the form of pre-defined
ModHandlers.

Best Regards,

		Tito.



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