Merge remote-tracking branch 'play-java-websocket-example/2.6.x' into…

… 2.6.x

* play-java-websocket-example/2.6.x: (83 commits)
  Nest play-java-websocket-example
  Updated with template-control on 2019-02-13T20:25:39.721Z (playframework#100)
  Upgrade branch 2.6.x using TemplateControl (playframework#96)
  Upgrade branch 2.6.x using TemplateControl (playframework#94)
  Upgrade branch 2.6.x using TemplateControl (playframework#93)
  Updated with template-control on 2019-01-08T14:44:42.192Z (playframework#90)
  Updated with template-control on 2019-01-04T17:13:23.935Z (playframework#85)
  Upgrade branch 2.6.x using TemplateControl (playframework#84)
  Upgrade branch 2.6.x using TemplateControl (playframework#81)
  Updated with template-control on 2018-09-11T20:14:50.523Z (playframework#79)
  Updated with template-control on 2018-08-20T20:37:13.896Z (playframework#78)
  Updated with template-control on 2018-07-19T01:58:55.842Z (playframework#76)
  Updated with template-control on 2018-07-16T18:38:45.656Z (playframework#75)
  Upgrade branch 2.6.x using TemplateControl (playframework#74)
  Updated with template-control on 2018-05-27T23:54:09.712Z (playframework#73)
  Updated with template-control on 2018-04-06T19:34:58.514Z (playframework#71)
  Updated with template-control on 2018-03-02T18:56:28.527Z (playframework#70)
  Upgrade branch 2.6.x using TemplateControl (playframework#69)
  Fix cross build to sbt 1.1.0 (playframework#68)
  Upgrade branch 2.6.x using TemplateControl (playframework#67)
  ...

play-java-websocket-example/.gitignore

@@ -0,0 +1,10 @@
+logs
+target
+build
+/.idea
+/.idea_modules
+/.classpath
+/.project
+/.gradle
+/.settings
+/RUNNING_PID

play-java-websocket-example/.mergify.yml

@@ -0,0 +1,27 @@
+pull_request_rules:
+  - name: automatic merge on CI success require review
+    conditions:
+      - status-success=Travis CI - Pull Request
+      - "#approved-reviews-by>=1"
+      - "#changes-requested-reviews-by=0"
+      - label!=block-merge
+    actions:
+      merge:
+        method: squash
+        strict: smart
+
+  - name: automatic merge on CI success for TemplateControl
+    conditions:
+      - status-success=Travis CI - Pull Request
+      - label=merge-when-green
+      - label!=block-merge
+    actions:
+      merge:
+        method: squash
+        strict: smart
+
+  - name: delete branch after merge
+    conditions:
+      - merged
+    actions:
+      delete_head_branch: {}

play-java-websocket-example/.travis.yml

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+language: scala
+scala:
+  - 2.12.8
+
+before_install:
+  - curl -sL https://github.com/shyiko/jabba/raw/master/install.sh | bash && . ~/.jabba/jabba.sh
+
+env:
+  global:
+    - JABBA_HOME=$HOME/.jabba
+  matrix:
+    # There is no concise way to specify multi-dimensional build matrix:
+    # https://github.com/travis-ci/travis-ci/issues/1519
+    - SCRIPT=scripts/test-sbt     [email protected]
+    - SCRIPT=scripts/test-sbt     [email protected]
+    - SCRIPT=scripts/test-gradle  [email protected]
+    - SCRIPT=scripts/test-gradle  [email protected]
+
+# Exclude some combinations from build matrix. See:
+# https://docs.travis-ci.com/user/customizing-the-build/#Build-Matrix
+matrix:
+  fast_finish: true
+  allow_failures:
+    # Current release of Gradle still does not supports Play 2.7.x releases
+    # As soon as there is a release of Gradle that fixes that, we can then
+    # remove this allowed failure.
+    - env: SCRIPT=scripts/test-gradle  [email protected]
+    - env: SCRIPT=scripts/test-gradle  [email protected]
+    # Java 11 is still not fully supported. It is good that we are already
+    # testing our sample applications to better discover possible problems
+    # but we can allow failures here too.
+    - env: SCRIPT=scripts/test-sbt     [email protected]
+
+install:
+  - $JABBA_HOME/bin/jabba install $TRAVIS_JDK
+  - unset _JAVA_OPTIONS
+  - export JAVA_HOME="$JABBA_HOME/jdk/$TRAVIS_JDK" && export PATH="$JAVA_HOME/bin:$PATH" && java -Xmx32m -version
+
+script:
+  - $SCRIPT
+
+before_cache:
+  - find $HOME/.ivy2 -name "ivydata-*.properties" -delete
+  - find $HOME/.sbt -name "*.lock" -delete
+
+cache:
+  directories:
+    - "$HOME/.ivy2/cache"
+    - "$HOME/.gradle/caches"
+    - "$HOME/.jabba/jdk"

play-java-websocket-example/LICENSE

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+CC0 1.0 Universal
+
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play-java-websocket-example/NOTICE

@@ -0,0 +1,8 @@
+Written by Lightbend <[email protected]>
+
+To the extent possible under law, the author(s) have dedicated all copyright and
+related and neighboring rights to this software to the public domain worldwide.
+This software is distributed without any warranty.
+
+You should have received a copy of the CC0 Public Domain Dedication along with
+this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

play-java-websocket-example/README.md

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+# play-websocket-java-example
+
+[![Build Status](https://travis-ci.org/playframework/play-java-websocket-example.svg?branch=2.6.x)](https://travis-ci.org/playframework/play-java-websocket-example) [![GitHub issues](https://img.shields.io/github/issues/playframework/play-websocket-java.svg?style=flat)](https://github.com/playframework/play-websocket-java/issues) [![GitHub forks](https://img.shields.io/github/forks/playframework/play-websocket-java.svg?style=flat)](https://github.com/playframework/play-websocket-java/network) [![GitHub stars](https://img.shields.io/github/stars/playframework/play-websocket-java.svg?style=flat)](https://github.com/playframework/play-websocket-java/stargazers)
+
+This is an example Play application that shows how to use Play's Websocket API in Java, by showing a series of stock tickers updated using WebSocket.
+
+The Websocket API is built on Akka Streams, and so is async, non-blocking, and backpressure aware.  Using Akka Streams also means that interacting with Akka Actors is simple.
+
+There are also tests showing how Junit and Akka Testkit are used to test actors and flows.
+
+## Reactive Push
+
+This application uses a WebSocket to push data to the browser in real-time.  To create a WebSocket connection in Play, first a route must be defined in the `routes` file.  Here is the route which will be used to setup the WebSocket connection:
+
+```routes
+GET /ws controllers.Application.ws
+```
+
+The `ws` method in the HomeController.java controller handles the request and does the protocol upgrade to the WebSocket connection.  The `UserActor` stores the handle to the WebSocket connection.
+
+Once the `UserActor` is created, the default stocks (defined in `application.conf`) are added to the user's list of watched stocks.
+
+Each stock symbol has its own `StockActor` defined in StockActor.java.  This actor holds the last 50 prices for the stock.  Using a `FetchHistory` message the whole history can be retrieved.  A `FetchLatest` message will generate a new price.  Every `StockActor` sends itself a `FetchLatest` message every 75 milliseconds.  Once a new price is generated it is added to the history and then a message is sent to each `UserActor` that is watching the stock.  The `UserActor` then serializes the data as JSON and pushes it to the client using the WebSocket.
+
+Underneath the covers, resources (threads) are only allocated to the Actors and WebSockets when they are needed.  This is why Reactive Push is scalable with Play and Akka.
+
+## Reactive UI - Real-time Chart
+
+On the client-side, a Reactive UI updates the stock charts every time a message is received.  The `index.scala.html` file produces the web page at <http://localhost:9000> and loads the JavaScript and CSS needed render the page and setup the UI.
+
+The JavaScript for the page is compiled from the index.coffee file which is written in CoffeeScript (an elegant way to write JavaScript).  Using jQuery, a page ready handler sets up the WebSocket connection and sets up functions which will be called when the server sends a message to the client through the WebSocket:
+
+```coffee
+$ ->
+  ws = new WebSocket $("body").data("ws-url")
+  ws.onmessage = (event) ->
+    message = JSON.parse event.data
+```
+
+The message is parsed and depending on whether the message contains the stock history or a stock update, a stock chart is either created or updated.  The charts are created using the **Flot** JavaScript charting library.  Using CoffeeScript, jQuery, and Flot makes it easy to build Reactive UI in the browser that can receive WebSocket push events and update the UI in real-time.
+
+## Reactive Requests
+
+When a web server gets a request, it allocates a thread to handle the request and produce a response.  In a typical model the thread is allocated for the entire duration of the request and response, even if the web request is waiting for some other resource.  A Reactive Request is a typical web request and response, but handled in an asynchronous and non-blocking way on the server.  This means that when the thread for a web request is not actively being used, it can be released and reused for something else.
+
+In the Reactive Stocks application the service which determines the stock sentiments is a Reactive Request.  The route is defined in the `routes` file:
+
+```routes
+GET /sentiment/:symbol controllers.StockSentiment.get(symbol)
+```
+
+A `GET` request to `/sentiment/GOOG` will call `get("GOOG")` on the StockSentiment.java controller.  That method begins with:
+
+```scala
+def get(symbol: String): Action[AnyContent] = Action.async {
+```
+
+The `async` block indicates that the controller will return a `Future[Result]` which is a handle to something that will produce a `Result` in the future.  The `Future` provides a way to do asynchronous handling but doesn't necessarily have to be non-blocking.  Often times web requests need to talk to other systems (databases, web services, etc).  If a thread can't be deallocated while waiting for those other systems to respond, then it is blocking.
+
+In this case a request is made to Twitter and then for each tweet, another request is made to a sentiment service.  All of these requests, including the request from the browser, are all handled as Reactive Requests so that the entire pipeline is Reactive (asynchronous and non-blocking).  This is called Reactive Composition.
+
+## Reactive Composition
+
+Combining multiple Reactive Requests together is Reactive Composition.  The StockSentiment controller does Reactive Composition since it receives a request, makes a request to Twitter for tweets about a stock, and then for each tweet it makes a request to a sentiment service.  All of these requests are Reactive Requests.  None use threads when they are waiting for a response.  Scala's **for comprehensions** make it very easy and elegant to do Reactive Composition.  The basic structure is:
+
+```scala
+for {
+  tweets <- tweetsFuture
+  sentiments <- Future.sequence(futuresForTweetSentiment(tweets))
+} yield Ok(sentiments)
+```
+
+Because the web client library in Play, `WS`, is asynchronous and non-blocking, all of the requests needed to get a stock's sentiments are Reactive Requests.  Combined together these Reactive Requests are Reactive Composition.
+
+## Reactive UI - Sentiments
+
+The client-side of Reactive Requests and Reactive Composition is no different than the non-Reactive model.  The browser makes an Ajax request to the server and then calls a JavaScript function when it receives a response.  In the Reactive Stocks application, when a stock chart is flipped over it makes the request for the stock's sentiments.  That is done using jQuery's `ajax` method in the index.coffee file.  When the request returns data the `success` handler updates the UI.
+
+## Further Learning
+
+For more information, please see the documentation for Websockets and Akka Streams:
+
+* <https://www.playframework.com/documentation/latest/JavaWebSockets>
+* <http://doc.akka.io/docs/akka/current/java/stream/stream-flows-and-basics.html#stream-materialization>
+* <http://doc.akka.io/docs/akka/current/java/stream/stream-integrations.html#integrating-with-actors>

play-java-websocket-example/app/Module.java

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+import actors.*;
+import com.google.inject.AbstractModule;
+import play.libs.akka.AkkaGuiceSupport;
+
+@SuppressWarnings("unused")
+public class Module extends AbstractModule implements AkkaGuiceSupport {
+    @Override
+    protected void configure() {
+        bindActor(StocksActor.class, "stocksActor");
+        bindActor(UserParentActor.class, "userParentActor");
+        bindActorFactory(UserActor.class, UserActor.Factory.class);
+    }
+}

play-java-websocket-example/app/actors/Messages.java

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+package actors;
+
+import stocks.Stock;
+
+import java.util.Set;
+
+import static java.util.Objects.requireNonNull;
+
+public final class Messages {
+
+    public static final class WatchStocks {
+        final Set<String> symbols;
+
+        public WatchStocks(Set<String> symbols) {
+            this.symbols = requireNonNull(symbols);
+        }
+
+        @Override
+        public String toString() {
+            return "WatchStocks(" + symbols.toString() + ")";
+        }
+    }
+
+    public static final class UnwatchStocks {
+        final Set<String> symbols;
+
+        public UnwatchStocks(Set<String> symbols) {
+            this.symbols = requireNonNull(symbols);
+        }
+
+        @Override
+        public String toString() {
+            return "UnwatchStocks(" + symbols.toString() + ")";
+        }
+    }
+
+    public static class Stocks {
+        final Set<Stock> stocks;
+
+        public Stocks(Set<Stock> stocks) {
+            this.stocks = requireNonNull(stocks);
+        }
+    }
+}
+

play-java-websocket-example/app/actors/StocksActor.java

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+package actors;
+
+import akka.actor.AbstractActor;
+import akka.event.Logging;
+import akka.event.LoggingAdapter;
+import stocks.Stock;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+
+/**
+ * This actor contains a set of stocks internally that may be used by
+ * all websocket clients.
+ */
+public class StocksActor extends AbstractActor {
+
+    private final Map<String, Stock> stocksMap = new HashMap<>();
+
+    private final LoggingAdapter log = Logging.getLogger(getContext().system(), this);
+
+    @Override
+    public Receive createReceive() {
+        return receiveBuilder()
+                .match(Messages.WatchStocks.class, watchStocks -> {
+                    Set<Stock> stocks = watchStocks.symbols.stream()
+                            .map(symbol -> stocksMap.compute(symbol, (k, v) -> new Stock(k)))
+                            .collect(Collectors.toSet());
+                    sender().tell(new Messages.Stocks(stocks), self());
+                }).build();
+    }
+}