Settings WebSocket adapter

Rather than interacting with with the Topical API directly, you can expose Topical from your web server. Separate adapters exist for Cowboy and WebSock (for use with Plug and Bandit).

In both cases, the Topical registry must be specified (Todo.Registry in the examples below).

cowboy-adapter

Cowboy adapter

If you're using Cowboy, the adapter can be added to your routes:

:cowboy_router.compile([
  {:_,
   [
     # ...
     {"/socket", Topical.Adapters.Cowboy.WebsocketHandler, registry: Todo.Registry}
   ]}
])

websock-adapter

WebSock adapter

The WebSock adapter is compatible with Plug (and Bandit):

defmodule Router do
  use Plug.Router

  plug :match
  plug :dispatch

  # ...

  get "/socket" do
    conn
    |> WebSockAdapter.upgrade(
      Topical.Adapters.Plug.WebSockServer,
      [registry: Todo.Registry],
      timeout: 60_000
    )
    |> halt()
  end

  # ...
end

context

Context

Optionally, an init function can be passed, which will be called before the connection is upgraded. It will be passed the Cowboy request or Plug conn, and must return {:ok, context}. The context will then be passed to the topic. This can be useful for authentication: for unauthenticated users, return an error result to prevent the socket getting established; for authenticated users, include the user ID in the context so it can be used for authorisation/identification within a topic.

client

Client

You can now connect to Topical from a JavaScript client.