Docs on fromSinkAndSource #25468 (#28349)

akka-docs/src/test/java/jdocs/stream/operators/flow/FromSinkAndSource.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2009-2019 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package jdocs.stream.operators.flow;
+
+import akka.NotUsed;
+import akka.actor.ActorSystem;
+import akka.actor.Cancellable;
+import akka.japi.Pair;
+import akka.stream.javadsl.*;
+import akka.stream.testkit.TestPublisher;
+import akka.stream.testkit.TestSubscriber;
+import akka.util.ByteString;
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscriber;
+
+import java.time.Duration;
+import java.util.concurrent.CompletionStage;
+
+public class FromSinkAndSource {
+
+  void halfClosedTcpServer() {
+    ActorSystem system = null;
+    // #halfClosedTcpServer
+    // close in immediately
+    Sink<ByteString, NotUsed> sink = Sink.cancelled();
+    // periodic tick out
+    Source<ByteString, Cancellable> source =
+        Source.tick(Duration.ofSeconds(1), Duration.ofSeconds(1), "tick")
+            .map(tick -> ByteString.fromString(System.currentTimeMillis() + "\n"));
+
+    Flow<ByteString, ByteString, NotUsed> serverFlow = Flow.fromSinkAndSource(sink, source);
+
+    Source<Tcp.IncomingConnection, CompletionStage<Tcp.ServerBinding>> connectionStream =
+        Tcp.get(system).bind("127.0.0.1", 9999);
+
+    connectionStream.runForeach(
+        incomingConnection -> incomingConnection.handleWith(serverFlow, system), system);
+    // #halfClosedTcpServer
+  }
+
+  void chat() {
+    ActorSystem system = null;
+    // #chat
+    Pair<Sink<String, NotUsed>, Source<String, NotUsed>> pair =
+        MergeHub.of(String.class).toMat(BroadcastHub.of(String.class), Keep.both()).run(system);
+    Sink<String, NotUsed> sink = pair.first();
+    Source<String, NotUsed> source = pair.second();
+
+    Flow<ByteString, ByteString, NotUsed> framing =
+        Framing.delimiter(ByteString.fromString("\n"), 1024);
+
+    Sink<ByteString, NotUsed> sinkWithFraming =
+        framing.map(bytes -> bytes.utf8String()).to(pair.first());
+    Source<ByteString, NotUsed> sourceWithFraming =
+        source.map(text -> ByteString.fromString(text + "\n"));
+
+    Flow<ByteString, ByteString, NotUsed> serverFlow =
+        Flow.fromSinkAndSource(sinkWithFraming, sourceWithFraming);
+
+    Tcp.get(system)
+        .bind("127.0.0.1", 9999)
+        .runForeach(
+            incomingConnection -> incomingConnection.handleWith(serverFlow, system), system);
+    // #chat
+  }
+
+  <In, Out> void myApiThatTakesAFlow(Flow<In, Out, NotUsed> flow) {
+    throw new UnsupportedOperationException();
+  }
+
+  void testing() {
+    ActorSystem system = null;
+    // #testing
+    TestSubscriber.Probe<String> inProbe = TestSubscriber.probe(system);
+    TestPublisher.Probe<String> outProbe = TestPublisher.probe(0, system);
+    Flow<String, String, NotUsed> testFlow =
+        Flow.fromSinkAndSource(Sink.fromSubscriber(inProbe), Source.fromPublisher(outProbe));
+
+    myApiThatTakesAFlow(testFlow);
+    inProbe.expectNext("first");
+    outProbe.expectRequest();
+    outProbe.sendError(new RuntimeException("test error"));
+    // ...
+    // #testing
+  }
+}