Do any of these options support communicating via an http API instead of stdin/out?

Ideally I'd like to have a standalone websocket service that handles long-running connections and then calls my specified API eg. `POST <my-http-service>/websocket/client/<client_id>`. Then the service can respond by sending a `POST <my-websocket-service>/websocket/client/<client>`, like an opensource https://pusher.com? I realise it'd be fairly easy to build myself, just wondering if there is something off the shelf that achieves this?