jondubois
commented
8 years ago Yes but you should keep in mind that a user could have multiple sockets open (on different browser tabs for example).
There are multiple ways to do what you want:
- If you only intend to ever have 1 worker process, then on the client you can simply emit the message to the server, then you can handle that event from inside your worker, then get a reference to the target client socket using the
scServer.clientsproperty here: http://socketcluster.io/#!/docs/api-scserver and then emit the message to that socket directly. Note that this approach is not scalable - As soon as you add a second worker, half of the sockets will be hosted by a different worker than the one which is handling the message so it won't work. This approach is not recommended. - You can setup backend-only channels using the
worker.exchangeobject here: http://socketcluster.io/#!/docs/api-scworker. With this approach; whenever a new socket becomes connected, you can create a new channel from the server which is based on that socket's ID and subscribe to it (E.g.worker.exchange.subscribe('someSocketId123').watch(handlerFunction)) - The handlerFunction can then just capture all messages published to that channel and forward them to the appropriate client socket usingsocket.emit(...). Your server logic will be responsible for listening to events from clients usingsocket.on(eventName, handler)and relaying them to the appropriate backend channel usingworker.exchange.publish('someSocketId123', message). You may want to set theallowClientPublishconfig of SC tofalse(see http://socketcluster.io/#!/docs/api-socketcluster) so that only the server can publish to channels. The idea of this approach would be to setup all channels on the backend only - That way clients only communicate to the server usingsocket.emit(...)and by listening to events usingsocket.on(...). Unlike the first approach, this one can scale quite well, but it means you have to manage channels on the backend (you have to remember to unsubscribe and destroy() the channel when the socket disconnects for example).
I think handling the channels on the frontend is generally a better/simpler approach overall but I understand that every case is different.
zalmoxisus
Kamelia2000
Is there a way to emit a message from one socket to another one (knowing the socket.id) instead of creating a channel, subscribing to it and adding a middleware to prevent watching it by other users (which is somehow cumbersome)?