I'm using the xmpppy library to write an XMPP client that can chat with users. It has its own XMPP user account and needs to know if a given user is online. However, the documentation is a bit sparse on how to do this. What would you recommend?
The only solution I've seen thus far is to start up a daemon before the XMPP server starts and monitor all presence messages that are sent out - then a user is said to be online if they've sent the "I'm online"-type message but not the corresponding "I'm logging off" message. However, being new to XMPP in general, I would think there would be a nicer way to do this.
The simple way is to support "subscribe" presence message -- this lets another user check if you're currently present (if they don't already know) by a "subscribe" attempt. Check this useful guide to get started, and the standard for many more important details (esp. on protecting your privacy, if needed, from subscribe requests from user you don't know).