How to use socket pub/sub

[mugendi]

Hello all, I'm building an app via HyperExpress and I'm not sure how to use the pub/sub feature for websockets.

Tried to find an example without much success. Anyone?

[kartikk221]

Hello, please see the Websocket component documentation for pub/sub with the MQTT syntax. In simple terms, you would have a flow where whenever a Websocket connection is received, you subscribe to a certain topic and then you can dispatch notifications over those topic(s) with the Server.publish method.

[mugendi]

Thank you very much @kartikk221

server.publish was the missing link! I was able to figure out the rest but that one part. The documentation here indicates that publish is a method of ws, which it is. The trouble I had was that determining what socket to run ws.publish from as publishing from a websocket instance, even though it works just fine, means the publishing websocket does not receive the event. Eventually I ended up creating a 'publish only' websocket on the server itself (esssentially a server-server websocket) and using that to ws.publish to all other client sockets. But that felt very wrong, even though it worked, so that's why I asked.

Turns out there is a server.publish method too! Thank you so much. I think this needs to be documented. I can create a PR when I have the time just to document that bit.

[kartikk221]

Oh I see, will make a note of that in the documentation for future changes.