RE: XML is _post_ OO

[Michael Brennan <Michael_Brennan@allegis.com>]

> From: Jeff Lowery [mailto:jlowery@scenicsoft.com]
> Sent: Tuesday, May 22, 2001 11:36 AM
> [...]
> I've yet to see
> a clearly articulated vision of what this post-OO (god, I 
> hope there's a
> better name than that) world will look like. What would I, as 
> a developer,
> stand to gain by refactoring <buzz> my objects into data model and
> functional model?

In most cases, I don't think you'd gain anything. I think that would be a
step backward. If folks are seriously maintaining that XML makes OO
obsolete, I would contend that that is absurd, and all evidence points to
the contrary. If XML makes OO obsolete, then why do we have a DOM? Why do we
have so many developers and vendors working on data-binding technologies?
What about the "web services" buzz that is attracting growing developer
mindshare, and which pushes XML down to an underlying "plumbing" layer
masked by OO APIs? In the "web services" community, the "post-OO" world
looks... well, very OO.

The success of XML does point to one fact that more sensible developers have
known all along: OO is not a panacea, and does not solve every problem. OO
just happens to be the best paradigm for software development that anyone
has come up with, so far. XML hasn't changed that. But OO does not address
the situation very well in which information needs to be external to an
application and shared with other applications (which may run on a different
platform, use a different programming language, have different runtime
libraries available, etc.). It also does not deal, very well, with more
dynamic information models that are not very explicitly defined at
development time. XML is very useful for these sorts of thing. OO is still
very useful as a programming paradigm for dealing with XML, but when
information needs to be shared, it is important to factor out that
information model from the OO model that is specific to your own use of that
information.

Database-centric applications had to contend with this issue long before XML
gained prominence. In the enterprise world it has been the norm to write OO
applications that deal with data in relational databases. It has always been
important in such applications to factor out the data model that must be
shared within the enterprise from the OO model that is specific to one
application that needs to use that data. XML has not fundamentally changed
that; it has simply provided a richer, more flexible mechanism for dealing
with that shared data.

XML doesn't solve every problem, either. XML and OO can be useful
complements to each other; neither is the end-all or be-all of computing.