ZIO backends¶

The ZIO backends are asynchronous. Sending a request is a non-blocking, lazily-evaluated operation and results in a response wrapped in a zio.Task. There’s a transitive dependency on zio.

To use, add the following dependency to your project:

"com.softwaremill.sttp.client" %% "async-http-client-backend-zio" % "2.0.0-RC11"

This backend depends on async-http-client and uses Netty behind the scenes.

Next you’ll need to add an implicit value:

import sttp.client.asynchttpclient.zio.AsyncHttpClientZioBackend

AsyncHttpClientZioBackend().flatMap { implicit backend => ... }

// or, if you'd like to use custom configuration:
AsyncHttpClientZioBackend.usingConfig(asyncHttpClientConfig).flatMap { implicit backend => ... }

// or, if you'd like to use adjust the configuration sttp creates:
AsyncHttpClientZioBackend.usingConfigBuilder(adjustFunction, sttpOptions).flatMap { implicit backend => ... }

// or, if you'd like to instantiate the AsyncHttpClient yourself:
implicit val sttpBackend = AsyncHttpClientZioBackend.usingClient(asyncHttpClient)

Streaming¶

To use streaming using zio-streams, add the following dependency instead:

"com.softwaremill.sttp.client" %% "async-http-client-backend-zio-streams" % "2.0.0-RC11"

And use the sttp.client.asynchttpclient.ziostreams.AsyncHttpClientZioStreamsBackend backend implementation. The backend supports streaming of type Stream[Throwable, ByteBuffer].

Requests can be sent with a streaming body:

import sttp.client._
import sttp.client.asynchttpclient.ziostreams._

import java.nio.ByteBuffer

import zio._
import zio.stream._

AsyncHttpClientZioStreamsBackend().flatMap { implicit backend =>
  val s: Stream[Throwable, ByteBuffer] =  ...

  basicRequest
    .streamBody(s)
    .post(uri"...")
}

And receive response bodies as a stream:

import sttp.client._
import sttp.client.asynchttpclient.ziostreams._

import java.nio.ByteBuffer

import zio._
import zio.stream._

import scala.concurrent.duration.Duration

AsyncHttpClientZioStreamsBackend().flatMap { implicit backend =>
  val response: Task[Response[Either[String, Stream[Throwable, ByteBuffer]]]] =
    basicRequest
      .post(uri"...")
      .response(asStream[Stream[Throwable, ByteBuffer]])
      .readTimeout(Duration.Inf)
      .send()
}

Websockets¶

The ZIO backend supports:

high-level, “functional” websocket interface, through the sttp.client.asynchttpclient.zio.ZioWebSocketHandler
low-level interface by wrapping a low-level Java interface, sttp.client.asynchttpclient.WebSocketHandler

See websockets for details on how to use the high-level and low-level interfaces.