It strikes me that the application that is going to make the public sit up and
notice XML is the one that lets me ask: "Make a table of all hotels in New York
that cost less than $100 and are within walking distance of Central Park."
The good news is that this application is completely possible (and almost, but
not quite, inevitable). The bad news is that it's still a ways off. What it
requires is enough people writing their Web documents in XML (with widely
accepted element tag names) to make it worthwhile for the search engines to
offer this kind of functionality.
There are probably a number of ways to jump-start this process, but the most
obvious is a browser that supports XML+XSL so that Web masters are willing to
write in XML. (Sorry to those of you who find browser support of XML boring.)
We also need namespaces, one or more Yahoo-like repositories for semi-standard
DTDs/schemas (see www.schema.net for a start), and a solution to Tim's
ought-to-be-famous "interesting and difficult problem of compounding DTDs".
I suggest that a short-term solution for the latter is to simply combine
elements from different DTDs as one sees fit. Although the resulting documents
are not valid wrt their original DTDs and cannot be used by DTD-specific
applications, XML does not require valid documents and the use of standard tags
facilitates the search process. I am advocating a certain degree of anarchy
here, but the Web is inherently anarchic and if we wait until we find a way to
combine DTDs without breaking DTD-specific applications, we're missing the
chance to build some extremely useful applications right now.
(By the way, a nice feature of XML editors that would help this along would be
to read DTDs/schemas from said Yahoo-like repositories, let users insert
elements whereever they want from whatever DTDs/schemas they want, and generate
new DTDs as requested.)
In the mean time, XML is still extremely useful as a data transport and I agree
with Chris von See, who said that XML's greatest potential is in data-based, not
document-based, applications. Just because the public won't see it doesn't mean
they won't (indirectly) appreciate it.
-- Ron Bourret