Target specific socket connections? about socket.io-redis-adapter

[peteruithoven]

I created a redis pub/sub wrapper with a callback system. This allows me to, from one instance, execute a emit on another instance and retrieve the response using a callback.
https://www.npmjs.org/package/redis-pubsubber

[objectiveSee]

If you need to emit events to socket.io instances from a non-socket.io process, you should use socket.io-emitter.

[peteruithoven]

Thanks I'll have a look at that, maybe there is a workaround there.
But I'm actually in the situation where I use a clustered socket.io server. Now I would like to forward a message from one client (that's for example on instance A) to a specific other client (that's for example on instance B). So all instances are socket.io servers.

[shantanuthatte]

Use rooms, and send the message to the room with the client you desire.
Every client gets its own room with a unique id. So, sending it just to the
room with the id would work.

Regards,
Shantanu Thatte
On Oct 1, 2014 4:24 PM, "Peter Uithoven" [email protected] wrote:

Thanks I'll have a look at that, maybe there is a workaround there.
But I'm actually in the situation where I use a clustered socket.io
server. Now I would like to forward a message from one client (that's for
example on instance A) to a specific other client (that's for example on
instance B). So all instances are socket.io servers.

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[peteruithoven]

I'll try.
I'm sorry I forgot to mention that I would like to use acknowledgment callbacks. I tried putting the target client into a room with a custom name (so I don't have to store the socket.io id in a database), but then it becomes a broadcast (to possible multiple clients) and then I can't specify a acknowledgment callback. So I tried retrieving the clients from a room, so I could target them specifically, but retrieving the clients from rooms isn't possible yet (#13).

[peteruithoven]

I just want to confirm that talking to a client of another socket.io server can be done by using their socket.io id as room name. It also works when you put this target client in a custom room with a fixed name and talk to that room from another socket.io server instance.
This means that socket.io-redis does support rooms, it just can't list the clients in rooms. It probably can't list the rooms that exist in other servers either.

But sadly, emitting into a room is considered broadcasting, probably because there can be multiple clients in a room, so you can't use callbacks. You'll get the following error when trying:

Callbacks are not supported when broadcasting

[peteruithoven]

So I see two possible solutions:

• Find a way to create a fake socket (so I can use existing callback code)
• Broadcast to a room and build my own callback system, see: socketio/socket.io#1656 (comment)