ratpack.sse

Class ServerSentEvents

java.lang.Object

ratpack.sse.ServerSentEvents

public class ServerSentEvents
extends Object

A renderable object for streaming server side events.

A renderer for this type is implicitly provided by Ratpack core.

Example usage:

 import ratpack.handling.Handler;
 import ratpack.handling.Context;
 import ratpack.func.Function;
 import ratpack.stream.Streams;
 import ratpack.launch.HandlerFactory;
 import ratpack.launch.LaunchConfig;
 import ratpack.launch.LaunchConfigBuilder;
 import ratpack.http.client.ReceivedResponse;
 import ratpack.sse.ServerSentEvent;
 import ratpack.test.embed.EmbeddedApplication;
 import ratpack.test.embed.LaunchConfigEmbeddedApplication;
 import ratpack.test.http.TestHttpClient;
 import ratpack.test.http.TestHttpClients;

 import static ratpack.sse.ServerSentEvents.serverSentEvents;

 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.ScheduledExecutorService;
 import org.reactivestreams.Publisher;

 import com.google.common.collect.Lists;
 import com.google.common.base.Joiner;

 public class Example {

   private static EmbeddedApplication createApp() {
     return new LaunchConfigEmbeddedApplication() {
       protected LaunchConfig createLaunchConfig() {
         return LaunchConfigBuilder.noBaseDir().port(0).build(new HandlerFactory() {
             public Handler create(LaunchConfig launchConfig) {

               // Example of streaming chunks

               return new Handler() {
                 public void handle(Context context) {
                   // simulate streaming by periodically publishing
                   ScheduledExecutorService executor = context.getLaunchConfig().getExecController().getExecutor();
                   Publisher<ServerSentEvent> eventStream = Streams.periodically(executor, 5, TimeUnit.MILLISECONDS, new Function<Integer, ServerSentEvent>() {
                     public ServerSentEvent apply(Integer i) {
                       if (i.intValue() < 5) {
                         return new ServerSentEvent(i.toString(), "counter", "event " + i);
                       } else {
                         return null;
                       }
                     }
                   });

                   context.render(serverSentEvents(eventStream));
                 }
               };

             }
           });
       }
     };
   }

   public static void main(String[] args) {
     try(EmbeddedApplication app = createApp()) {
       ReceivedResponse response = app.getHttpClient().get();
       assert response.getHeaders().get("Content-Type").equals("text/event-stream;charset=UTF-8");

       List<String> outputEvents = Lists.transform(Lists.newArrayList(0, 1, 2, 3, 4), new com.google.common.base.Function<Integer, String>() {
         public String apply(Integer i) {
           return "event: counter\ndata: event " + i + "\nid: " + i + "\n";
         }
       });

       String expectedOutput = Joiner.on("\n").join(outputEvents) + "\n";
       assert response.getBody().getText().equals(expectedOutput);
     }
   }

 }
 

See Also:

Wikipedia - Using server-sent events, MDN - Using server-sent events

Method Summary

Methods

Modifier and Type	Method and Description
org.reactivestreams.Publisher<? extends ServerSentEvent>	getPublisher()
static ServerSentEvents	serverSentEvents(org.reactivestreams.Publisher<? extends ServerSentEvent> publisher)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

serverSentEvents

public static ServerSentEvents serverSentEvents(org.reactivestreams.Publisher<? extends ServerSentEvent> publisher)

getPublisher

public org.reactivestreams.Publisher<? extends ServerSentEvent> getPublisher()