[RE: SAX2/Java: Towards a final form]

[James Layer]

David Megginson <david at megginson.com> wrote:
>Miles Sabin writes:
 > David Megginson wrote,
 > > 1. Deprecate Parser, DocumentHandler, and AttributeList.
 > 
 > <snip/>
 > 
 > >  public interface XMLReader extends Parser
 > 
 > If Parser and the rest are deprecated, then why do you want
 > XMLReader to extend Parser?

> Comments?

While I share Miles' sentiments regarding legacy baggage, I believe David's
deprecation approach would promote a more rapid (and smoother) adoption of the
new interface (at least at the company where I work).

We have abstracted the 'get a parser' process so our app developers request a
parser based (primarily) on functionality rather than demanding a specific
implementation; we can swap parsers in and out with little or no impact to
existing applications as a consequence.

If I understand the new (proposed) interface properly, our current
getXXXParser methods can simply return XMLReader (after the SAX2 stuff is
plopped in) which still downcasts elegantly to those apps that still expect
Parser.  These apps can then be upgraded in a more leisurely fashion (during
the next update or bug fix cycle) while new apps can immediately begin using
the proper (XMLReader) interface. 

The same thing could of course be accomplished using adapter techniques but
that appears to result in an additional intermediate phase (and release cycle)
where adapters are injected until all apps are upgraded and then removed.

Regards,

Jim Layer





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