by lrosenth


September 13, 2007

In my opinion, XML is one of the most misunderstood technologies in existence today. And it is amazing because XML, itself, is so elementary. I think that is the source of the misunderstanding – the simplicity. Let me explain.

XML was first established as a “recommendation” (their name for a standard) by the W3C in February 1998, 9 years ago. Around 2001 one of the Adobe executives told all the Adobe product groups that they had to make use of XML in their products. For the most part no one knew what that meant. At the same time, I was also experiencing crazy statements being made at the Seybold conferences about XML that made no sense to me at all.

So I put together a presentation about XML that I presented at the 2002 Adobe internal Technology Summit where all the engineers in the company gather for a 3-day conference. In that presentation (see the entry for XML/PDF) I said two rather outlandish things:
o XML is not a markup language despite what its name says (extensible markup language), and
o You may not just say "XML" anymore at Adobe you must say "XML for <something>," like XML for news feeds, or XML for Graphics, or XML for Job Tickets.

Yes, this will sound rather self-serving, but I think that talk made a huge impact on the Adobe product groups’ ability to act on the directive to support XML in their products. And now Adobe does make extensive use of XML for a lot of things.

XML is not in and of itself a markup language, but it is a set of rules and a notation for inventing markup languages. The term markup came from the earlier practice of editorially marking text galleys for publication with red pencil. It later evolved into ways to markup text for typesetting. Some interesting history.

I have often made a rather simplistic analogy, using the term “XML” is similar to saying “the Roman alphabet,” as in I just wrote a poem using the Roman alphabet. That statement isn’t too illuminating since there are dozens of languages that use the Roman alphabet. Much more information is conveyed if instead I said "I just wrote a poem in German which uses the Roman alphabet." So to say something is XML hardly says anything. It says that you used the rules and notation.

Much more useful is to say what particular XML markup language was used. And there are thousands of XML markup languages that all use the XML notation and rules, just as there are dozens of natural languages that use the Roman alphabet. See also.

So please don’t say anything is just XML but talk about particular XML markup languages. You will find that your communications will take a big step toward being more meaningful. Really!

And if you have time, go look at the annotated slide presentation I mentioned above. That presentation also covers one other hang-up I have about people’s understanding of XML and I will address that in yet another blog titled something like “XML Documents”.

(As an aside and to help you get to know me better, I do have some credentials in this area since I worked at IBM Research for 19 years and used their GML which latter evolved to become an ISO standard called SGML (ISO 8879:1986) which was simplified and had a couple of key attributes added and became XML. So I have lived with this stuff for over 30 years.)

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