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On Tuesday 29 October 2002 18:43, Anthony B. Coates wrote:
> ** Reply to message from Jeff Lowery <jlowery@scenicsoft.com> on Tue, 29
> Oct 2002 10:25:39 -0800
>
> > > Sure, and I've seen enormous problems come out of people
> > > "compiling" XML schemas into classes using the tools that are now
> > > available. I mean, one of the main reasons for using XML is to decouple
> > > applications, and then people compile the XML schemas into code so that
> > > they tightly couple their applications to this week's version of the
> > > XML.
> >
> > How about instead of generating classes, these code generators generated
> > interfaces + implementations? Still not perfect, but at least you're
> > coding your app to an interface. You can then change the interface,
> > either through extension or dynamic proxies. The implementation classes
> > can also be extended, or rewritten altogether if needs be.
>
> No, no help at all. It's not a problem that you solve by trying to use
> another Java feature. The problem is if the auto-generated XML->Java code
> is called from all throughout the application codebase. If the XML
> changes, everything breaks. You need to hide the auto-generated code
> behind a facade so that almost all of the application code is unable to
> call it directly. Then, when there are changes to the XML, the effect on
> the codebase is limited to a small, pre-determined set of classes.
>
How about coding to an abstract data model with greater expressive power than
a simple XML schema (small s). Like a topic map or RDF abstraction for
example ? (I'm only slightly joking here ;-)
Other folks have already said this, but the point about XML data binding is
that your schema is the contract between the data provider and the data
consumer. If the data provider breaks the contract or if you are working in
an environment where such contracts are not worth the bits they are encoded
in, then its probably true to say that XML data binding is not for you...
Cheers,
Kal
--
Kal Ahmed, techquila.com
XML and Topic Map Consultancy
e: kal@techquila.com
p: +44 7968 529531
w: www.techquila.com
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