Play WS Standalone

Play WS is a powerful HTTP Client library, originally developed by the Play team for use with Play Framework. It uses AsyncHttpClient for HTTP client functionality and has no Play dependencies.

We've provided some documentation here on how to use Play WS in your app (without Play). For more information on how to use Play WS in Play, please refer to the Play documentation.

Getting Started

To get started, you can add play-ahc-ws-standalone as a dependency in SBT:

libraryDependencies += "com.typesafe.play" %% "play-ahc-ws-standalone" % "LATEST_VERSION"

Where you replace LATEST_VERSION with the version shown in this image: .

This adds the standalone version of Play WS, backed by AsyncHttpClient. This library contains both the Scala and Java APIs, under play.api.libs.ws and play.libs.ws.

To add XML and JSON support using Play-JSON or Scala XML, add the following:

libraryDependencies += "com.typesafe.play" %% "play-ws-standalone-xml" % playWsStandaloneVersion
libraryDependencies += "com.typesafe.play" %% "play-ws-standalone-json" % playWsStandaloneVersion

Shading

Play WS uses shaded versions of AsyncHttpClient and OAuth Signpost, repackaged under the play.shaded.ahc and play.shaded.oauth package names, respectively. Shading AsyncHttpClient means that the version of Netty used behind AsyncHttpClient is completely independent of the application and Play as a whole.

Specifically, shading AsyncHttpClient means that there are no version conflicts introduced between Netty 4.0 and Netty 4.1 using Play WS.

NOTE: If you are developing play-ws and publishing shaded-asynchttpclient and shaded-oauth using sbt publishLocal, you need to be aware that updating ~/.ivy2/local does not overwrite ~/.ivy2/cache and so you will not see your updated shaded code until you remove it from cache. See http://eed3si9n.com/field-test for more details. This bug has been filed as sbt/sbt#2687.

Shaded AHC Defaults

Because Play WS shades AsyncHttpClient, the default settings are also shaded and so do not adhere to the AHC documentation. This means that the settings in ahc-default.properties and the AsyncHttpClient system properties are prepended with play.shaded.ahc, for example the usePooledMemory setting in the shaded version of AsyncHttpClient is defined like this:

play.shaded.ahc.org.asynchttpclient.usePooledMemory=true

Typed Bodies

The type system in Play-WS has changed so that the request body and the response body can use richer types.

You can define your own BodyWritable or BodyReadable, but if you want to use the default out of the box settings, you can import the type mappings with the DefaultBodyReadables / DefaultBodyWritables.

Scala

import play.api.libs.ws.DefaultBodyReadables._
import play.api.libs.ws.DefaultBodyWritables._

More likely you will want the XML and JSON support:

import play.api.libs.ws.XMLBodyReadables._
import play.api.libs.ws.XMLBodyWritables._

or

import play.api.libs.ws.JsonBodyReadables._
import play.api.libs.ws.JsonBodyWritables._

To use a BodyReadable in a response, you must type the response explicitly:

val responseBody: Future[scala.xml.Elem] = ws.url(...).get().map { response =>
  response.body[scala.xml.Elem]
}

or using Play-JSON:

val jsonBody: Future[JsValue] = ws.url(...).get().map { response =>
  response.body[JsValue]
}

Note that there is a special case: when you are streaming the response, then you should get the body as a Source:

ws.url(...).stream().map { response =>
   val source: Source[ByteString, NotUsed] = response.bodyAsSource
}

To POST, you should pass in a type which has an implicit class mapping of BodyWritable:

val stringData = "Hello world"
ws.url(...).post(stringData).map { response => ... }

You can also define your own custom BodyReadable:

case class Foo(body: String)

implicit val fooBodyReadable = BodyReadable[Foo] { response =>
  import play.shaded.ahc.org.asynchttpclient.{ Response => AHCResponse }
  val ahcResponse = response.asInstanceOf[StandaloneAhcWSResponse].underlying[AHCResponse]
  Foo(ahcResponse.getResponseBody)
}

or custom BodyWritable:

implicit val writeableOf_Foo: BodyWritable[Foo] = {
  // https://tools.ietf.org/html/rfc6838#section-3.2
  BodyWritable(foo => InMemoryBody(ByteString.fromString(foo.serialize)), application/vnd.company.category+foo)
}

Java

To use the default type mappings in Java, you should use the following:

import play.libs.ws.DefaultBodyReadables;
import play.libs.ws.DefaultBodyWritables;

followed by:

public class MyClient implements DefaultBodyWritables, DefaultBodyReadables {    
    public CompletionStage<String> doStuff() {
      return client.url("http://example.com").post(body("hello world")).thenApply(response ->
        response.body(string())
      );
    }
}

Note that there is a special case: when you are using a stream, then you should get the body as a Source:

class MyClass {
    public CompletionStage<Source<ByteString, NotUsed>> readResponseAsStream() {
        return ws.url(url).stream().thenApply(response ->
            response.bodyAsSource()
        );
    }
}

You can also post a Source:

class MyClass {
    public CompletionStage<String> doStuff() {
        Source<ByteString, NotUsed> source = fromSource();
        return ws.url(url).post(source).thenApply(response ->
            response.body()
        );
    }
}

You can define a custom BodyReadable:

import play.libs.ws.ahc.*;
import play.shaded.ahc.org.asynchttpclient.Response;

class FooReadable implements BodyReadable<StandaloneWSResponse, Foo> {
    public Foo apply(StandaloneWSResponse response) {
        Response ahcResponse = (Response) response.getUnderlying();
        return Foo.serialize(ahcResponse.getResponseBody(StandardCharsets.UTF_8));
    }
}

You can also define your own custom BodyWritable:

public class MyClient {
    private BodyWritable<String> someOtherMethod(String string) {
      akka.util.ByteString byteString = akka.util.ByteString.fromString(string);
      return new DefaultBodyWritables.InMemoryBodyWritable(byteString, "text/plain");
    }
}

Instantiating a standalone client

The standalone client needs Akka to handle streaming data internally:

Scala

In Scala, the way to call out to a web service and close down the client:

package playwsclient

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import play.api.libs.ws._
import play.api.libs.ws.ahc._

import scala.concurrent.Future

object ScalaClient {
  import DefaultBodyReadables._
  import scala.concurrent.ExecutionContext.Implicits._

  def main(args: Array[String]): Unit = {
    // Create Akka system for thread and streaming management
    implicit val system = ActorSystem()
    system.registerOnTermination {
      System.exit(0)
    }
    implicit val materializer = ActorMaterializer()

    // Create the standalone WS client
    // no argument defaults to a AhcWSClientConfig created from
    // "AhcWSClientConfigFactory.forConfig(ConfigFactory.load, this.getClass.getClassLoader)"
    val wsClient = StandaloneAhcWSClient()

    call(wsClient)
      .andThen { case _ => wsClient.close() }
      .andThen { case _ => system.terminate() }
  }

  def call(wsClient: StandaloneWSClient): Future[Unit] = {
    wsClient.url("http://www.google.com").get().map { response ⇒
      val statusText: String = response.statusText
      val body = response.body[String]
      println(s"Got a response $statusText")
    }
  }
}

Java

In Java the API is much the same, except that an instance of AsyncHttpClient has to be passed in explicitly:

package playwsclient;

import akka.actor.ActorSystem;
import akka.stream.ActorMaterializer;
import akka.stream.ActorMaterializerSettings;
import com.typesafe.config.ConfigFactory;

import play.libs.ws.*;
import play.libs.ws.ahc.*;

import java.util.concurrent.CompletionStage;

public class JavaClient implements DefaultBodyReadables {

    public static void main(String[] args) {
        // Set up Akka materializer to handle streaming
        final String name = "wsclient";
        ActorSystem system = ActorSystem.create(name);
        system.registerOnTermination(() -> System.exit(0));
        final ActorMaterializerSettings settings = ActorMaterializerSettings.create(system);
        final ActorMaterializer materializer = ActorMaterializer.create(settings, system, name);

        // Create the WS client from the `application.conf` file, the current classloader and materializer.
        StandaloneAhcWSClient client = StandaloneAhcWSClient.create(
                AhcWSClientConfigFactory.forConfig(ConfigFactory.load(), system.getClass().getClassLoader()),
                materializer
        );

        client.url("http://www.google.com").get()
                .whenComplete((response, throwable) -> {
                    String statusText = response.getStatusText();
                    String body = response.body(string());
                    System.out.println("Got a response " + statusText);
                })
                .thenRun(() -> {
                    try {
                        client.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                })
                .thenRun(system::terminate);
    }
}

Caching

Play WS implements HTTP Caching through CachingAsyncHttpClient, AhcHTTPCache and CacheControl, a minimal HTTP cache management library in Scala.

To create a standalone AHC client that uses caching, pass in an instance of AhcHttpCache with a cache adapter to the underlying implementation. For example, to use Caffeine as the underlying cache, you could use the following:

class CaffeineHttpCache extends Cache {
     val underlying = Caffeine.newBuilder()
       .ticker(Ticker.systemTicker())
       .expireAfterWrite(365, TimeUnit.DAYS)
       .build[EffectiveURIKey, ResponseEntry]()

  override def remove(key: EffectiveURIKey): Unit = underlying.invalidate(key)
  override def put(key: EffectiveURIKey, entry: ResponseEntry): Unit = underlying.put(key, entry)
  override def get(key: EffectiveURIKey): ResponseEntry = underlying.getIfPresent(key)
  override def close(): Unit = underlying.cleanUp()
}
val cache = new CaffeineHttpCache()
val client = StandaloneAhcWSClient(httpCache = AhcHttpCache(cache))   

There are a number of guides that help with putting together Cache-Control headers:

• Mozilla's Guide to HTTP caching
• Mark Nottingham's Guide to Caching
• HTTP Caching
• REST Easy: HTTP Cache

Releasing

This project uses sbt-release to push to Sonatype and Maven. You will need Lightbend Sonatype credentials and a GPG key that is available on one of the public keyservers to release this project.

To release cleanly, you should clone this project fresh into a directory with writable credentials (i.e. you have ssh key to github):

mkdir releases
cd releases
git clone [email protected]:playframework/play-ws.git

and from there you can release:

cd play-ws
./release

The script will walk you through integration tests and publishing.

License

Play WS is licensed under the Apache license, version 2. See the LICENSE file for more information.