Websockets

Apart from streaming, backends (see backends summary) can also optionally support websockets. Websocket requests are described exactly the same as regular requests, starting with basicRequest, adding headers, specifying the request method and uri.

The difference is that instead of calling send(), openWebsocket(handler) should be called instead, given an instance of a backend-specific websocket handler. Refer to documentation of individual backends for details on how to instantiate the handler.

After opening a websocket, a WebSocketResponse instance is returned, wrapped in a backend-specific effects wrapper. If the protocol upgrade hasn’t been successfull, the request will fail with an error (represented as an exception or a failed effects wrapper).

In case of success, WebSocketResponse contains:

  • the headers returned when opening the websocket
  • a handler and backend-specific value