Comment by olau
11 years ago
At the time when XMPP was getting standardized and was still mostly known as Jabber, I started implementing a Jabber chat client with a friend.
The problem with XMPP isn't that it was based on XML. No, what made it annoying was that the dudes who made it decided that instead of basing it on exchanging individual messages, i.e. XML documents like everyone else does, everything must instead be put inside a so-called XML stream.
IIRC it basically meant that the exchange started with a start tag that wasn't terminated until the connection was closed. Since nothing at the time was designed to work with unfinished XML documents (remember the end tag doesn't come until you're done), all the convenient standard XML tools/libraries wouldn't work.
So I don't think XMPP is a stellar piece of work. But it's of course much better than some proprietary crap, and it's sad to see it lose support, although I imagine to Google and Facebook who both probably couldn't care less about interoperability, having an open XMPP interface is probably more of a liability (spammers, enables people to skip their ads) than something they get much perceived value out of.
Even though it seems like a strange decision, using XML for the stream framing made the protocol nicely pure. It theoretically meant you didn't need to write a parser (this was a rare thing for a network protocol). In practice, though, you're right, most parsers at the time didn't work well with network streams.
Of course, lack of adoption by the big providers was almost certainly political rather than technical.