Merge pull request #1370 from akka/wip-starter-∂π

add akka.Main and use that to add Hello World docs

akka-docs/rst/intro/getting-started.rst

@@ -115,6 +115,8 @@ directory.
 More information is available in the documentation of the
 :ref:`microkernel-scala` / :ref:`microkernel-java`.
 
+.. _build-tool:
+
 Using a build tool
 ------------------
 

akka-docs/rst/intro/index-java.rst

@@ -7,6 +7,7 @@ Introduction
    what-is-akka
    why-akka
    getting-started
+   ../java/hello-world
    deployment-scenarios
    use-cases
 

akka-docs/rst/intro/index-scala.rst

@@ -0,0 +1,13 @@
+Introduction
+============
+
+.. toctree::
+   :maxdepth: 2
+
+   what-is-akka
+   why-akka
+   getting-started
+   ../scala/hello-world
+   deployment-scenarios
+   use-cases
+

akka-docs/rst/java.rst

@@ -6,7 +6,7 @@ Java Documentation
 .. toctree::
    :maxdepth: 2
 
-   intro/index
+   intro/index-java
    general/index
    java/index-actors
    java/index-futures

akka-docs/rst/java/code/docs/actor/japi/Greeter.java

@@ -0,0 +1,26 @@
+/**
+ * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package docs.actor.japi;
+
+import akka.actor.UntypedActor;
+import java.io.Serializable;
+
+//#greeter
+public class Greeter extends UntypedActor {
+  
+  public static enum Msg {
+    GREET, DONE;
+  }
+  
+  @Override
+  public void onReceive(Object msg) {
+    if (msg == Msg.GREET) {
+      System.out.println("Hello World!");
+      getSender().tell(Msg.DONE, getSelf());
+    } else unhandled(msg);
+  }
+  
+}
+//#greeter

akka-docs/rst/java/code/docs/actor/japi/HelloWorld.java

@@ -0,0 +1,31 @@
+/**
+ * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package docs.actor.japi;
+
+//#hello-world
+import akka.actor.Props;
+import akka.actor.UntypedActor;
+import akka.actor.ActorRef;
+
+public class HelloWorld extends UntypedActor {
+
+  @Override
+  public void preStart() {
+    // create the greeter actor
+    final ActorRef greeter =
+        getContext().actorOf(Props.create(Greeter.class), "greeter");
+    // tell it to perform the greeting
+    greeter.tell(Greeter.Msg.GREET, getSelf());
+  }
+
+  @Override
+  public void onReceive(Object msg) {
+    if (msg == Greeter.Msg.DONE) {
+      // when the greeter is done, stop this actor and with it the application
+      getContext().stop(getSelf());
+    } else unhandled(msg);
+  }
+}
+//#hello-world

akka-docs/rst/java/hello-world.rst

@@ -0,0 +1,43 @@
+##########################
+The Obligatory Hello World
+##########################
+
+Since every programming paradigm needs to solve the tough problem of printing a
+well-known greeting to the console we’ll introduce you to the actor-based
+version.
+
+.. includecode:: ../java/code/docs/actor/japi/HelloWorld.java#hello-world
+
+The ``HelloWorld`` actor is the application’s “main” class; when it terminates
+the application will shut down—more on that later. The main business logic
+happens in the :meth:`preStart` method, where a ``Greeter`` actor is created
+and instructed to issue that greeting we crave for. When the greeter is done it
+will tell us so by sending back a message, and when that message has been
+received it will be passed into the :meth:`onReceive` method where we can
+conclude the demonstration by stopping the ``HelloWorld`` actor. You will be
+very curious to see how the ``Greeter`` actor performs the actual task:
+
+.. includecode:: ../java/code/docs/actor/japi/Greeter.java#greeter
+
+This is extremely simple now: after its creation this actor will not do
+anything until someone sends it a message, and if that happens to be an
+invitation to greet the world then the ``Greeter`` complies and informs the
+requester that the deed has been done.
+
+As a Java developer you will probably want to tell us that there is no
+``static public void main(...)`` anywhere in these classes, so how do we run
+this program? The answer is that the appropriate :meth:`main` method is
+implemented in the generic launcher class :class:`akka.Main` which expects only
+one command line argument: the class name of the application’s main actor. This
+main method will then create the infrastructure needed for running the actors,
+start the given main actor and arrange for the whole application to shut down
+once the main actor terminates. Thus you will be able to run the above code
+with a command similar to the following::
+
+  java -classpath <all those JARs> akka.Main com.example.HelloWorld
+
+This conveniently assumes placement of the above class definitions in package
+``com.example`` and it further assumes that you have the required JAR files for
+``scala-library`` and ``akka-actor`` available. The easiest would be to manage
+these dependencies with a build tool, see :ref:`build-tool`.
+

akka-docs/rst/scala.rst

@@ -6,7 +6,7 @@ Scala Documentation
 .. toctree::
    :maxdepth: 2
 
-   intro/index
+   intro/index-scala
    general/index
    scala/index-actors
    scala/index-futures

akka-docs/rst/scala/code/docs/actor/IntroDocSpec.scala

@@ -0,0 +1,50 @@
+/**
+ * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package docs.actor
+
+import akka.testkit.AkkaSpec
+
+//#hello-world
+import akka.actor.Actor
+import akka.actor.Props
+
+class HelloWorld extends Actor {
+
+  override def preStart(): Unit = {
+    // create the greeter actor
+    val greeter = context.actorOf(Props[Greeter], "greeter")
+    // tell it to perform the greeting
+    greeter ! Greeter.Greet
+  }
+
+  def receive = {
+    // when the greeter is done, stop this actor and with it the application
+    case Greeter.Done ⇒ context.stop(self)
+  }
+}
+//#hello-world
+
+//#greeter
+object Greeter {
+  case object Greet
+  case object Done
+}
+
+class Greeter extends Actor {
+  def receive = {
+    case Greeter.Greet ⇒
+      println("Hello World!")
+      sender ! Greeter.Done
+  }
+}
+//#greeter
+
+class IntroDocSpec extends AkkaSpec {
+
+  "demonstrate HelloWorld" in {
+    expectTerminated(watch(system.actorOf(Props[HelloWorld])))
+  }
+
+}

akka-docs/rst/scala/hello-world.rst

@@ -0,0 +1,44 @@
+##########################
+The Obligatory Hello World
+##########################
+
+Since every programming paradigm needs to solve the tough problem of printing a
+well-known greeting to the console we’ll introduce you to the actor-based
+version.
+
+.. includecode:: ../scala/code/docs/actor/IntroDocSpec.scala#hello-world
+
+The ``HelloWorld`` actor is the application’s “main” class; when it terminates
+the application will shut down—more on that later. The main business logic
+happens in the :meth:`preStart` method, where a ``Greeter`` actor is created
+and instructed to issue that greeting we crave for. When the greeter is done it
+will tell us so by sending back a message, and when that message has been
+received it will be passed into the behavior described by the :meth:`receive`
+method where we can conclude the demonstration by stopping the ``HelloWorld``
+actor. You will be very curious to see how the ``Greeter`` actor performs the
+actual task:
+
+.. includecode:: ../scala/code/docs/actor/IntroDocSpec.scala#greeter
+
+This is extremely simple now: after its creation this actor will not do
+anything until someone sends it a message, and if that happens to be an
+invitation to greet the world then the ``Greeter`` complies and informs the
+requester that the deed has been done.
+
+As a Scala developer you will probably want to tell us that there is no
+``main(Array[String])`` method anywhere in these classes, so how do we run this
+program? The answer is that the appropriate :meth:`main` method is implemented
+in the generic launcher class :class:`akka.Main` which expects only one command
+line argument: the class name of the application’s main actor. This main method
+will then create the infrastructure needed for running the actors, start the
+given main actor and arrange for the whole application to shut down once the
+main actor terminates. Thus you will be able to run the above code with a
+command similar to the following::
+
+  java -classpath <all those JARs> akka.Main com.example.HelloWorld
+
+This conveniently assumes placement of the above class definitions in package
+``com.example`` and it further assumes that you have the required JAR files for
+``scala-library`` and ``akka-actor`` available. The easiest would be to manage
+these dependencies with a build tool, see :ref:`build-tool`.
+