I was hoping to implement a simple XMPP server in Java.
What I need is a library which can parse and understand xmpp requests from a client. I have looked at Smack (mentioned below) and JSO. Smack appears to be client only so while it might help parsing packets it doesn’t know how to respond to clients. Is JSO maintained it looks very old. The only promising avenue is to pull apart Openfire which is an entire commercial (OSS) XMPP server.
I was just hoping for a few lines of code on top of Netty or Mina, so I could get started processing some messages off the wire.
Joe –
Well the answer to what I am trying to do is somewhat long – I’ll try to keep it short.
There are two things, that are only loosely related:
1) I wanted to write an XMPP server because I imagine writing a custom protocol for two clients to communicate. Basically I am thinking of a networked iPhone app – but I didn’t want to rely on low-level binary protocols because using something like XMPP means the app can ‘grow up’ very quickly from a local wifi based app to an internet based one…
The msgs exchanged should be relatively low latency, so strictly speaking a binary protocol would be best, but I felt that it might be worth exploring if XMPP didn’t introduce too much overhead such that I could use it and then reap benefits of it’s extensability and flexability later.
2) I work for Terracotta – so I have this crazy bent to cluster everything. As soon as I started thinking about writing some custom server code, I figured I wanted to cluster it. Terracotta makes scaling out Java POJOs trivial, so my thought was to build a super simple XMPP server as a demonstration app for Terracotta. Basically each user would connect to the server over a TCP connection, which would register the user into a hashmap. Each user would have a LinkedBlockingQueue with a listener thread taking message from the queue. Then any connected user that wants to send a message to any other user (e.g. any old chat application) simply issues an XMPP message (as usual) to that user over the connection. The server picks it up, looks up the corresponding user object in a map and places the message onto the queue. Since the queue is clustered, regardless of wether the destination user is connected to the same physical server, or a different physical server, the message is delivered and the thread that is listening picks it up and sends it back down the destination user’s tcp connection.
So – not too short of a summary I’m afraid. But that’s what I want to do. I suppose I could just write a plugin for Openfire to accomplish #1 but I think it takes care of a lot of plumbing so it’s harder to do #2 (especially since I was hoping for a very small amount of code that could fit into a simple 10-20kb Maven project).
http://xmpp.org/xmpp-software/libraries/ has a list of software libraries for XMPP. Here is an outdated snapshot of it:
ActionScript
C
C++
C# / .NET / Mono
Erlang
Flash
Haskell
Java
JavaScript
Lisp
Objective-C
Perl
PHP
Python
Ruby
Tcl