Re: [tlug] OT: XML?

[Matt Gushee <mgushee@example.com>]

On Tue, May 07, 2002 at 01:03:06PM +0900, Jean-Christian Imbeault wrote:
> 
> I've been reading up on XML this weekend (sparsely I admiit it) and was 
> interested in using it for for my web pages. However I couldn't find any 
> information on why using XML on plain web pages would be a Good Thing(tm). 

I'm not so sure it would.

I've been working with markup languages (first SGML, then XML) for several
years, and have been working as an XML consultant and trainer for the last
two. One thing that has become very apparent to me is that most users of
XML are large corporations. In fact, to make a gross generalization, there 
is a tremendous knowledge gap between large and small businesses. For many
corporate IT types, XML is already old news ... whereas last month I went
to a meeting of small business owners with web sites. I explained what I
do in what I thought were very simple terms, but I got a lot of blank
stares. Maybe 1 of the ~10 people in the room actually understood what
I was talking about.

Well, there's a reason for that ... I'm currently trying to find out if
it's a good reason or not, because I would really rather be working with
small businesses if I could.

The trouble is that using XML really effectively takes a lot of design 
work, or data modeling to be precise. If you're just going to throw 
something together, there isn't much point. Now, what I would like to
know is, how complex do the requirements have to be before the overhead
of a customized XML solution becomes worthwhile? As far as I know there
hasn't been any serious research on that point ... though there are 
similar questions you could ask (and that maybe have been asked and
answered) about other techniques and methodologies ... e.g., at what 
point does a formal methodology such as the Rational Unified Process 
become cost-effective for software development?

Or ... is there a way to make XML products and services generic enough
that individuals and small businesses can afford to use XML, and still
get real benefits out of it? Now, I'm not talking about products like
OpenOffice and MS Office, which use XML file formats, because in those
cases what gets saved is just formatting instructions, just as word
processor files have always been. They aren't attempting to encode 
semantics and structure, just using XML as an open, easily processable
file format (well in the MS case it's obfuscated to the hilt, but still
nominally open).

What's special about XML (or SGML or LaTeX, but very few people care
about them these days) is that it allows you to create self-describing
documents/datasets. But there's a small problem with that, which is that
it takes a lot of work to ensure that the descriptions you are encoding
are (a) appropriate to your content and (b) make sense to whoever you are
exchanging information with (or whatever system is processing that 
information). In the abstract, there should be a continuum between the
totally customized solutions that some corporations are spending millions
of bucks on, and the invisible, totally generic (and not very interesting)
XMLized products that you are probably already using. In the abstract,
there should be a way to implement XML solutions with just a little bit
of customization, that will help make information just a little more
manageable for small businesses, or make small websites just a little
easier to build and maintain. To my knowledge, nobody has yet found a
business model that would make that a reality.

> I could think of a few useult things such as making a web site more easily 
> searchable but other than that ...

That's the theory. Unfortunately, that falls into the large category of
largely unexploited uses of XML. That's partly because most of the effort
put into XML development by most vendors has focused on exchanging data
between applications or databases, and partly because effective searching
depends on natural language, and once again the techies have grossly
underestimated the complexity of natural language.

> Can anyone point me to any ressource that explain *why* and *how* XML can 
> be put to good use on a rather simple web site?

I don't know what you mean by simple, but broadly speaking I would say:

  * XML is very useful for complex, semi-structured documents or datasets
    (e.g., technical manuals and knowledge bases, insurance claims, medical
    or police records)

  * XML is useful for highly structured datasets such as financial accounts,
    but relational databases and compact, grid-structured exchanged formats
    are more useful. 
    
  * XML is not very useful for documents where content is secondary to
    presentation, such as many marketing documents.

  * There are an awful lot of borderline cases.

So I would say, if your goal is to learn XML, by all means use it for your
website. But if the site is as simple as you say it is, you might do just
as well by sticking with plain ol' HTML.

-- 
Matt Gushee
Englewood, Colorado, USA
mgushee@example.com
http://www.havenrock.com/