designing a one-to-one chat system in a dating website

1. -X makes a search
2. -X sends a friend request to Y
3. -Y accepts the request

Now your webapp must tell ejabberd to add X as contact of Y, and Y as contact of X. If you have the webapp and ejabberd in the same machine, this can be done with shell calls. Other solutions are to send XML-RPC calls, or REST HTTP calls. See later.

4. -Since then, X can view Y photos, details... but can also send a chat request (same for Y)

By default in Jabber/XMPP/ejabberd, you can chat with anybody, even if he is not in your roster. You don't need his pre-approval. Of course, if your users only use a client written by you, you can implement in your client this limitation: "you only can send messages to approved contacts".

5. -Y accepts the chat request and the session is now open between them.

In Jabber/XMPP/ejabberd there isn't conversation pre-approval. I consider normal that, when you accept/approve a new contact, you allow him to chat with you anytime.

Explanation of "this can be done with shell calls" when using ejabberd 2.1.0-beta2:
1. Install ejabberd
2. Download mod_admin_extra from ejabberd-modules SVN, compile, install and enable in config.
3. Start ejabberd
4. Create users x@localhost and y@localhost
For example:

$ ejabberdctl register x localhost mypassxx
User x@localhost succesfully registered

$ ejabberdctl register y localhost mypassyy
User y@localhost succesfully registered

5. Add both users as contacts. For example:

$ ejabberdctl add_rosteritem x localhost y localhost \"Mr. Y\" Friends both

$ ejabberdctl add_rosteritem y localhost x localhost \"Dr. X\" \"Friends from school\" both

6. Enter the ejabberd WebAdmin to verify the rosters were correctly updated.

If you prefer to use XML-RPC calls, install ejabberd_xmlrpc. If you prefer REST HTTP calls, install mod_rest.