jdev - 2021-11-16

Hi again. This java/smack XMPP client I am building shall make use of a MUC and users connect using nicknames. While I have seen this working once upon a time, now it does not and I am confused whether there is something I changed or there was a change on the server (that I do not manage). So my question is: How should the use of nicknames work in theory? What do I use on one side to set the nickname, how does another client connected to the same MUC receive the new nickname?

hiran: there are two ways to convey the nickname. The most common one is as the local part of the occupant JID, i.e. jdev@muc.xmpp.org/hiran

There is also https://xmpp.org/extensions/xep-0172.html which can embed a nickname element into presence and messages

So by default you set a nickname while joining a room, and then all the other occupants get a presence with it

Is there a chance to change the nickname while being connected? Is the nickname per MUC or per XMPP connection?

hiran: the nickname is per room and can be changed

hiran: https://download.igniterealtime.org/smack/docs/latest/javadoc/org/jivesoftware/smackx/muc/MultiUserChat.html#changeNickname(org.jxmpp.jid.parts.Resourcepart)

Ok. So what I have is (using the smack client library): resourcePart = Resourcepart.from(nickname); muc.changeNickname(resourcePart); From what you say probably I am creating the resourcePart wrongly

hiran: no, that looks good. But you can only change the nickname after you are already joined to the room.

Ok, first join the muc, then change the nickname. Hmm, when changing the nickname while I am in the MUC I receive exceptions. I programmed the client to leave the muc and join in again, then setting a new nickname.

There's also a way to register the nickname with the room, which is independent from the one that is used. It's then reserved and others may be prevented from using it.

But ok, now that we looked at the setting of the nickname - how would the other side see the nickname? I this a presence event on the other side?

hiran: why are you trying to *change* the nickname?

The XMPP client connects to the XMPP server on one side, then connects to a game on the other side. When the user loads a savegame the nick is changed to whatever character is in there.

Does that make sense?

hiran: a little bit. You need to have a nickname already when joining.

also which part is the MUC? Game server?

The MUC shall connect the users to each othere. Currently it is a peer to peer system - no dedicated server

hiran: also nicknames must be unique in a room.

That is not so much a problem. If the nick is not unique I get an error message, and users can rename themselves if need be

> also nicknames must be unique in a room. per user, or per connected client, depending on the server

Ok. I will check if the nicknames are set properly. How does another client get aware of the changed nick?

They should get a signal

hiran: there is a join presence for each change and each new member, see https://download.igniterealtime.org/smack/docs/latest/javadoc/org/jivesoftware/smackx/muc/MultiUserChat.html#addParticipantListener(org.jivesoftware.smack.PresenceListener) and https://download.igniterealtime.org/smack/docs/latest/javadoc/org/jivesoftware/smackx/muc/MultiUserChat.html#addParticipantStatusListener(org.jivesoftware.smackx.muc.ParticipantStatusListener)

What signal? I guess it should be a presence stanza

ParticipantListener? That might be something. So far I tried PresenceListener and PresenceEventListeners, but not yet Participants...

hiran: the ParticipantStatusListener will pre-process the presence for you

hiran: so you can add your business logic right into it

Even better

I will try those listeners :-)