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I don't agree with this at all. If XML is "rolling back the clock", why are
not developers tossing out their OO tools in favor of COBOL and FORTRAN
toolkits?
The truth is that this statement is premised on a rigid, dogmatic view of OO
that never held up in practice in the first place. In the distributed OO
world, developers had already moved toward patterns of employing lightweight
"value objects" that represent coarse-grained state information that can be
externalized by objects and shared with other objects. This pattern is
codified in Sun's J2EE blueprint docs, but it existed long before J2EE. I
used this pattern years ago as a Forte 4GL developer, and I strongly suspect
that enlightened CORBA developers used similar patterns.
XML gives us a more dynamic, malleable way to accomplish this same goal, and
so it has taken this pattern to a new level. This does not mean that OO is
obsolete. On the contrary, OO now has a much richer companion to offer
richer mechanisms for sharing coarse-grained state information. There are
certainly situations where an OO solution is not called for. But that has
always been the case, and OO systems still have a large role to play. The
misguided thinking that the XML structures a system shares with the rest of
the world must match the internal data structures used for processing is one
of the things that leads naive developers to do things like try to use a 1GB
XML document as a database. Encapsulation is still a good thing, but
enlightened developers understand that in complex environments, different
objects or systems may need to share coarse-grained data. The data that is
shared is not simply the objects externalizing their internal data. Rather
the shared data structures become part of the interface of the object, the
contract it abides by in interacting with other systems. It may look quite
different from what the objects use internally to support their processing
needs.
OO was never a panacea, even though it has been hyped as such by some
dogmatists. Today we hear from some dogmatists hyping XML as the panacea to
replace OO. The truth is they are very nice complements to each other for
any developer smart enough to avoid dogmatism and exercise common sense in
choosing appropriate solutions.
> From: Uche Ogbuji [mailto:uche.ogbuji@fourthought.com]
> Sent: Monday, January 14, 2002 8:51 PM
> To: Mike Champion
> Cc: xml-dev@lists.xml.org
> Subject: Re: [xml-dev] taking XML seriously (was RE:
> [xml-dev] XML=WAP?
> And DOA?)
>
>
>
> > Another XML 2001 presentation by Stephen Kirkham made similar
> > points
> > http://www.idealliance.org/papers/xml2001/papers/html/04-05-
> > 01.html
> > "In the Object oriented world data is a second class citizen.
> > Objects control access to and provide operations on data. ...
> > XML however starts to reverse the clock, it represents a
> > change in course back to a more data centric world, one in
> > which data has a life of it's own. Data has effectively
> > broken free of its object boundaries"
>
> Quite true, and nicely put. I've advocated this very POV
> several times on this list, including in the discussion of
> XML as "post-OO". I continue this thread in a recent column for Intel
>
> http://cedar.intel.com/cgi-bin/ids.dll/content/content.jsp?cnt
Key=Generic+Editorial%3a%3axml_p1&cntType=IDS_EDITORIAL&catCode=CAN
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