All these problems are fixable but I don't see the tide ever actually changing direction and "hey suddenly XMPP is cool again, we should all use it".
One thing is for certain... humanity needs standard, open and widely-used protocols for communication. And there's a lot of ground to cover: Text, audio, video; single and multiuser; topical (IRC-like); social (invite-based/people I know); Synchronous (IM) and asynchronous (email/offline messaging)...
XMPP tried to do a lot of that. Maybe it tried to do too much. Maybe you just can't do all that in one protocol. I don't know, I just hope we'll get there soon - if nothing else, I'm tired of maintaining those "best way to reach me" charts JoshM33k is talking about.
Not even remotely true! Prosody on Debian works out of the box, including federation. You just have to configure the domain name.
It's not hard to set up an XMPP server. It's hard to set up Ejabberd. Ejabberd is not the only XMPP server. Prosody is very easy to set up.
Honestly, people, think before you speak...
I didn't just make this up on the spot, I've been dealing with these issues for years. So yes, I've thought about them a lot.
I used to run a prosody server on my home box. It is great software and a fantastic daemon compared to ejabberd (edit: Configuration-wise that is) but fat lot of good that does if you don't know what XEPs to set up when dealing with other servers. I shut it down because it was pretty much useless and I wasn't able to talk to my gtalk buddies from it anymore.
I have no idea what XEPs to set up when dealing with other servers. I did not have to set up any such thing. Like I said, federation (server to server communication) works out of the box, at least on Debian.
Was that really necessary?
I had never heard of Prosody, any major difference cons/pros between the two?
One of the best things that could happen today I think is Google open sourcing the Hangouts protocol. It's a reasonable alternative to XMPP and has a massive userbase. The clients are pretty horrible but that might be completely unrelated to how good the protocol is (Note: I have no idea how good it is. Because it's closed source.).
I was hopeful for a while but I don't really see it happening anymore :( Oh well...
Edit: Oh and the worst part: Communication is just one side of that coin. The other side is identity and it's one hell of a side. OpenID was a disaster. Mozilla got it mostly right with Persona but completely botched the marketing and has all but given up on it now. There is no decent foss protocol for identity/authentication today other than Persona, and nobody is working on one. There was a time indeed where I could've pictured Google working on solving this just for the hell of it. Just because it would improve the world. That Google is gone, and there's nobody with the appropriate reach that seems willing to do it now.
I've worked with all three. The H.323 vs SIP battle was fought a long time ago... for better or worse, SIP won. Any H.323 systems still in the wild can probably be considered "legacy."
That being said, while H.323 has more "batteries included," its call flow is accordingly more complex. SIP is not too bad, there is some subtlety to it, but the main issue is that you have to piece together dozens of RFCs for an interoperable system, not to speak of implementation-specific quirks.
XMPP is the more appropriate protocol in this context -- IM and group chat -- because it has had presence and ad-hoc messaging baked in from the start, including reasonably supported MUC. Ultimately, XMPP's issues are similar to SIP's -- the patchwork of XEPs is too unwieldy to work with. For an example, compare the multimedia bits (eg, Jingle) and the corresponding SIP session setup flow. The stigma of being a XML-based protocol designed in the 90's doesn't help, either.
The biggest reason SIP is sticking around, however, is that it has major buy-in from the telcos with IMS/4G. However, SIP is also a more appropriate protocol for traditional telephony. In that respect, comparing SIP and XMPP is a bit like comparing apples to oranges. With the appropriate extensions, one could behave like the other, but it wouldn't be their strength.
SIP was adopted by 3GPP in 1999 to be used in the mobile networks. Of course, that trickled throughout the telcos, so it now is widely used in the telco space. H.323 was widely used for PSTN backhauling to reduce tolls. However, SIP is more prevalent there, I'd guess.
Enterprise networks still use both H.323 and SIP, with more desk phones using SIP and videoconferencing equipment split, but moving to SIP.
That said, any move to SIP these days is only because there is nothing better. WebRTC is the next big thing. It borrows SDP from SIP, but no signaling protocol is defined.
Personally, I'd like to realize the vision behind what was intended to be H.325, which was to be a JSON-based signalling protocol that is fully distributed. Each application could implement whatever protocol it wanted, and they would all be associated through H.325, giving the user the feeling that these different applications work closely together. That would be possible, even when applications run on different devices.
Alas, there seems to be no financial motivator for those that control the market to explore that concept, so we're stuck with H.323, SIP, and WebRTC (and various proprietary glue pieces). The trend these days seems to be toward proprietary solutions, providing limited interop with others through SIP. Limited, as in nothing but basic voice and video.
