Storing Lots of Fiddly Bits (was Re: What is XML for?)

[Borden, Jonathan]

>
Uche Ogbuji wrote:
>
> > Your comments give me the impression that this is unacceptable to you
> > in the XML/heirarchical universe.  You don't want DOM at any level.
> > You insist on going straight to objects.  It is not even good enough
> > to build an object layer on top of the DOM layer.  I find this a
> > little implausible and hence am certain that you had something else in
> > mind.  Is it rather that you simply don't care what the underlying API
> > is, that you are only interested in what happens at the object level?
>
> I hope I'm not mis-representing Paul here, but as I've always
> read him (and
> agreed), his point is that XML, and the various ancillary
> technologies such as
> DOM and XML Schema, are more appropriate for content-exchange
> than for core
> business-object modeling.

	Ah, yes but realize that business object modelling is done at a higher
level than the relational table (which is a data structure). XML is the
serialization of the DOM tree based data structure. When business object
need to employ tree based data structures, they may choose to store these in
XML serializations. Another option would be for these business objects to
interact with a database through the same DOM interfaces. This way the
business object layer is isolated from the details of the storage layer.

>
> I don't think it makes sense to build a business-object model on
> top of DOM,

	No doubt, if you are dealing with tabular data you ought stick with a
relational model and use recordsets. If my business objects find it
convenient or otherwise useful to employ DOM interfaces, who are you to
suggest otherwise? The issue is one of performance. If a low memory, high
performance DOM implementation were to appear I guarentee this would be
found quite useful. For example, if you decide to build a business object
model on top of ODI's eXcelon, which is described as providing a DOM
interface, then you would indeed be building a business-object model on top
of DOM. If Microsoft, Oracle, POET, Sybase, IBM, Informix etc etc. come out
with high performance native DOM interfaces on their databases then you
would have effectively isolated your business-object model from the database
vendor. The point is that the existence of the DOM doesn't eliminate the
need to built business objects, yet it still has an important place as a
standards based interface onto trees (i.e. its the closest thing to groves
we are likely to see in widescale use).


Jonathan Borden
http://jabr.ne.mediaone.net


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