OkHttp backend

To use, add the following dependency to your project:

"com.softwaremill.sttp.client" %% "okhttp-backend" % "2.0.0-RC6"
// or, for the monix version:
"com.softwaremill.sttp.client" %% "okhttp-backend-monix" % "2.0.0-RC6"

This backend depends on OkHttp, and offers:

  • a synchronous backend: OkHttpSyncBackend
  • an asynchronous, Future-based backend: OkHttpFutureBackend
  • an asynchronous, Monix-Task-based backend: OkHttpMonixBackend

OkHttp fully supports HTTP/2.


The OkHttp backend supports websockets, where the websocket handler is of type sttp.client.okhttp.WebSocketHandler. An instance of this handler can be created in two ways.

The first (“high-level” one), available when using the Monix variant, is to pass a MonixWebSocketHandler(). This will create a websocket handler and expose a sttp.client.ws.WebSocket[Task] interface for sending/receiving messages.

See websockets for details on how to use the high-level interface.

Second (“low-level”), given an OkHttp-native okhttp3.WebSocketListener, you can lift it to a web socket handler using WebSocketHandler.fromListener. This listener will receive lifecycle callbacks, as well as a callback each time a message is received. Note that the callbacks will be executed on the Netty (network) thread, so make sure not to run any blocking operations there, and delegate to other executors/thread pools if necessary. The value returned in the WebSocketResponse will be an instance of okhttp3.WebSocket, which allows sending messages.