3 parts of routing a websocket

First, there's a socket declaration in the lib/appname/endpoint.ex file.

  socket "/socket", AppName.UserSocket

Second, there's a transport declaration in the web/channels/user_socket.ex file.

  transport :ws, Phoenix.Transports.WebSocket

Now, the websocket will be available at the url ws://localhost:4000/socket/ws the final path segment of the url being added by the first argument of the transport declaration.

Finally, the channel topic is also declared in the user_socket.ex file.

channel "app_topic:*", AppName.MyChannel

Now every json body that has a topic attribute of app_topic will be routed to MyChannel.AppName where it will be handled appropriately based on the event attribute.

{"topic":"app_topic:something","event":"phx_join","payload":{},"ref":"1"}