> > So JSON may be a good alternative.
> 
> I would never discourage you from looking for the best 
> language to meet your needs, and JSON is in many respects 
> simpler than XML.  That said, keep in mind that JSON is 
> fundamentally aimed at what we informally call "data", I.e. 
> roughly the sorts of things that fit well into a Java, C, or 
> (of course) Javascript structure.  

When XML was first conceived, I think most people expected it to be used
primarily for documents (I had heard people talking about using SGML for
data in the 1980s, and I thought they were nuts). It's interesting to review
why XML proved successful as a data interchange format even though it wasn't
primarily designed for that role.

* XML was very cheap to implement (cost of writing tools, cost of buying
tools, cost of putting them to good use)

* For some reason I have never understood, XML had no serious competition,
and had universal endorsement from all influential players

* XML filled a gap. Many people with data interchange problems had devised
custom solutions at layer 6 of the stack, and they all involved a lot of
effort to maintain, and no generic tooling was available. These solutions
often failed to solve the character sets problem. Other people had adopted
ASN.1, which was unaffordable by the masses ($100K for a parser).

* XML was genuinely open and platform-independent: people trusted the
independence of the authority responsible for the specification, and there
was neither an explicit nor a covert bias to particular operating systems,
vendors, or programming languages. And there were no doubts about what was
or was not valid XML (as there are with JSON).

* For the first time in the history of computing, people were finding that
documents and data could no longer be kept separate. People were building
web sites in which information, entertainment, and transactions needed to be
seamlessly mixed.

* The high level of redundancy in XML, which we love to complain about,
proved a winner in making it easy to formats to evolve gracefully.

If JSON had been around before XML, the first three arguments would have
been far less compelling. But the others would still have been strong.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay