Polish WebSocket samples

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/SampleTomcatWebSocketApplication.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.context.web.SpringBootServletInitializer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.socket.WebSocketHandler;
+import org.springframework.web.socket.config.annotation.EnableWebSocket;
+import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
+import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
+import org.springframework.web.socket.handler.PerConnectionWebSocketHandler;
+import org.springframework.web.socket.server.standard.ServerEndpointExporter;
+
+import samples.websocket.client.GreetingService;
+import samples.websocket.client.SimpleGreetingService;
+import samples.websocket.echo.DefaultEchoService;
+import samples.websocket.echo.EchoService;
+import samples.websocket.echo.EchoWebSocketHandler;
+import samples.websocket.reverse.ReverseWebSocketEndpoint;
+import samples.websocket.snake.SnakeWebSocketHandler;
+
+@Configuration
+@EnableAutoConfiguration
+@EnableWebSocket
+public class SampleTomcatWebSocketApplication extends SpringBootServletInitializer
+		implements WebSocketConfigurer {
+
+	@Override
+	public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
+		registry.addHandler(echoWebSocketHandler(), "/echo").withSockJS();
+		registry.addHandler(snakeWebSocketHandler(), "/snake").withSockJS();
+	}
+
+	@Override
+	protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
+		return application.sources(SampleTomcatWebSocketApplication.class);
+	}
+
+	@Bean
+	public EchoService echoService() {
+		return new DefaultEchoService("Did you say \"%s\"?");
+	}
+
+	@Bean
+	public GreetingService greetingService() {
+		return new SimpleGreetingService();
+	}
+
+	@Bean
+	public WebSocketHandler echoWebSocketHandler() {
+		return new EchoWebSocketHandler(echoService());
+	}
+
+	@Bean
+	public WebSocketHandler snakeWebSocketHandler() {
+		return new PerConnectionWebSocketHandler(SnakeWebSocketHandler.class);
+	}
+
+	@Bean
+	public ReverseWebSocketEndpoint reverseWebSocketEndpoint() {
+		return new ReverseWebSocketEndpoint();
+	}
+
+	@Bean
+	public ServerEndpointExporter serverEndpointExporter() {
+		return new ServerEndpointExporter();
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(SampleTomcatWebSocketApplication.class, args);
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/client/GreetingService.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.client;
+
+public interface GreetingService {
+
+	String getGreeting();
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/client/SimpleClientWebSocketHandler.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.client;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.socket.TextMessage;
+import org.springframework.web.socket.WebSocketSession;
+import org.springframework.web.socket.handler.TextWebSocketHandler;
+
+public class SimpleClientWebSocketHandler extends TextWebSocketHandler {
+
+	protected Log logger = LogFactory.getLog(SimpleClientWebSocketHandler.class);
+
+	private final GreetingService greetingService;
+
+	private final CountDownLatch latch;
+
+	private final AtomicReference<String> messagePayload;
+
+	@Autowired
+	public SimpleClientWebSocketHandler(GreetingService greetingService,
+			CountDownLatch latch, AtomicReference<String> message) {
+		this.greetingService = greetingService;
+		this.latch = latch;
+		this.messagePayload = message;
+	}
+
+	@Override
+	public void afterConnectionEstablished(WebSocketSession session) throws Exception {
+		TextMessage message = new TextMessage(this.greetingService.getGreeting());
+		session.sendMessage(message);
+	}
+
+	@Override
+	public void handleTextMessage(WebSocketSession session, TextMessage message)
+			throws Exception {
+		this.logger.info("Received: " + message + " (" + this.latch.getCount() + ")");
+		session.close();
+		this.messagePayload.set(message.getPayload());
+		this.latch.countDown();
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/client/SimpleGreetingService.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.client;
+
+public class SimpleGreetingService implements GreetingService {
+
+	@Override
+	public String getGreeting() {
+		return "Hello world!";
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/echo/DefaultEchoService.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.echo;
+
+public class DefaultEchoService implements EchoService {
+
+	private final String echoFormat;
+
+	public DefaultEchoService(String echoFormat) {
+		this.echoFormat = (echoFormat != null) ? echoFormat : "%s";
+	}
+
+	@Override
+	public String getMessage(String message) {
+		return String.format(this.echoFormat, message);
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/echo/EchoService.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.echo;
+
+public interface EchoService {
+
+	String getMessage(String message);
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/echo/EchoWebSocketHandler.java

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+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.echo;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.socket.CloseStatus;
+import org.springframework.web.socket.TextMessage;
+import org.springframework.web.socket.WebSocketHandler;
+import org.springframework.web.socket.WebSocketSession;
+import org.springframework.web.socket.handler.TextWebSocketHandler;
+
+/**
+ * Echo messages by implementing a Spring {@link WebSocketHandler} abstraction.
+ */
+public class EchoWebSocketHandler extends TextWebSocketHandler {
+
+	private static Logger logger = LoggerFactory.getLogger(EchoWebSocketHandler.class);
+
+	private final EchoService echoService;
+
+	@Autowired
+	public EchoWebSocketHandler(EchoService echoService) {
+		this.echoService = echoService;
+	}
+
+	@Override
+	public void afterConnectionEstablished(WebSocketSession session) {
+		logger.debug("Opened new session in instance " + this);
+	}
+
+	@Override
+	public void handleTextMessage(WebSocketSession session, TextMessage message)
+			throws Exception {
+		String echoMessage = this.echoService.getMessage(message.getPayload());
+		logger.debug(echoMessage);
+		session.sendMessage(new TextMessage(echoMessage));
+	}
+
+	@Override
+	public void handleTransportError(WebSocketSession session, Throwable exception)
+			throws Exception {
+		session.close(CloseStatus.SERVER_ERROR);
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/reverse/ReverseWebSocketEndpoint.java

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+/*
+ * Copyright 2012-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.reverse;
+
+import java.io.IOException;
+
+import javax.websocket.OnMessage;
+import javax.websocket.Session;
+import javax.websocket.server.ServerEndpoint;
+
+@ServerEndpoint("/reverse")
+public class ReverseWebSocketEndpoint {
+
+	@OnMessage
+	public void handleMessage(Session session, String message) throws IOException {
+		session.getBasicRemote().sendText(
+				"Reversed: " + new StringBuilder(message).reverse());
+	}
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/Direction.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+public enum Direction {
+	NONE, NORTH, SOUTH, EAST, WEST
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/Location.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+public class Location {
+
+	public int x;
+	public int y;
+	public static final int GRID_SIZE = 10;
+	public static final int PLAYFIELD_HEIGHT = 480;
+	public static final int PLAYFIELD_WIDTH = 640;
+
+	public Location(int x, int y) {
+		this.x = x;
+		this.y = y;
+	}
+
+	public Location getAdjacentLocation(Direction direction) {
+		switch (direction) {
+		case NORTH:
+			return new Location(this.x, this.y - Location.GRID_SIZE);
+		case SOUTH:
+			return new Location(this.x, this.y + Location.GRID_SIZE);
+		case EAST:
+			return new Location(this.x + Location.GRID_SIZE, this.y);
+		case WEST:
+			return new Location(this.x - Location.GRID_SIZE, this.y);
+		case NONE:
+			// fall through
+		default:
+			return this;
+		}
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+
+		Location location = (Location) o;
+
+		if (this.x != location.x) {
+			return false;
+		}
+		if (this.y != location.y) {
+			return false;
+		}
+
+		return true;
+	}
+
+	@Override
+	public int hashCode() {
+		int result = this.x;
+		result = 31 * result + this.y;
+		return result;
+	}
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/Snake.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+import java.util.ArrayDeque;
+import java.util.Collection;
+import java.util.Deque;
+
+import org.springframework.web.socket.TextMessage;
+import org.springframework.web.socket.WebSocketSession;
+
+public class Snake {
+
+	private static final int DEFAULT_LENGTH = 5;
+
+	private final int id;
+	private final WebSocketSession session;
+
+	private Direction direction;
+	private int length = DEFAULT_LENGTH;
+	private Location head;
+	private final Deque<Location> tail = new ArrayDeque<Location>();
+	private final String hexColor;
+
+	public Snake(int id, WebSocketSession session) {
+		this.id = id;
+		this.session = session;
+		this.hexColor = SnakeUtils.getRandomHexColor();
+		resetState();
+	}
+
+	private void resetState() {
+		this.direction = Direction.NONE;
+		this.head = SnakeUtils.getRandomLocation();
+		this.tail.clear();
+		this.length = DEFAULT_LENGTH;
+	}
+
+	private synchronized void kill() throws Exception {
+		resetState();
+		sendMessage("{'type': 'dead'}");
+	}
+
+	private synchronized void reward() throws Exception {
+		this.length++;
+		sendMessage("{'type': 'kill'}");
+	}
+
+	protected void sendMessage(String msg) throws Exception {
+		this.session.sendMessage(new TextMessage(msg));
+	}
+
+	public synchronized void update(Collection<Snake> snakes) throws Exception {
+		Location nextLocation = this.head.getAdjacentLocation(this.direction);
+		if (nextLocation.x >= SnakeUtils.PLAYFIELD_WIDTH) {
+			nextLocation.x = 0;
+		}
+		if (nextLocation.y >= SnakeUtils.PLAYFIELD_HEIGHT) {
+			nextLocation.y = 0;
+		}
+		if (nextLocation.x < 0) {
+			nextLocation.x = SnakeUtils.PLAYFIELD_WIDTH;
+		}
+		if (nextLocation.y < 0) {
+			nextLocation.y = SnakeUtils.PLAYFIELD_HEIGHT;
+		}
+		if (this.direction != Direction.NONE) {
+			this.tail.addFirst(this.head);
+			if (this.tail.size() > this.length) {
+				this.tail.removeLast();
+			}
+			this.head = nextLocation;
+		}
+
+		handleCollisions(snakes);
+	}
+
+	private void handleCollisions(Collection<Snake> snakes) throws Exception {
+		for (Snake snake : snakes) {
+			boolean headCollision = this.id != snake.id
+					&& snake.getHead().equals(this.head);
+			boolean tailCollision = snake.getTail().contains(this.head);
+			if (headCollision || tailCollision) {
+				kill();
+				if (this.id != snake.id) {
+					snake.reward();
+				}
+			}
+		}
+	}
+
+	public synchronized Location getHead() {
+		return this.head;
+	}
+
+	public synchronized Collection<Location> getTail() {
+		return this.tail;
+	}
+
+	public synchronized void setDirection(Direction direction) {
+		this.direction = direction;
+	}
+
+	public synchronized String getLocationsJson() {
+		StringBuilder sb = new StringBuilder();
+		sb.append(String.format("{x: %d, y: %d}", Integer.valueOf(this.head.x),
+				Integer.valueOf(this.head.y)));
+		for (Location location : this.tail) {
+			sb.append(',');
+			sb.append(String.format("{x: %d, y: %d}", Integer.valueOf(location.x),
+					Integer.valueOf(location.y)));
+		}
+		return String.format("{'id':%d,'body':[%s]}", Integer.valueOf(this.id),
+				sb.toString());
+	}
+
+	public int getId() {
+		return this.id;
+	}
+
+	public String getHexColor() {
+		return this.hexColor;
+	}
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/SnakeTimer.java

@@ -0,0 +1,109 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import org.apache.juli.logging.Log;
+import org.apache.juli.logging.LogFactory;
+
+/**
+ * Sets up the timer for the multi-player snake game WebSocket example.
+ */
+public class SnakeTimer {
+
+	private static final Log log = LogFactory.getLog(SnakeTimer.class);
+
+	private static Timer gameTimer = null;
+
+	private static final long TICK_DELAY = 100;
+
+	private static final ConcurrentHashMap<Integer, Snake> snakes = new ConcurrentHashMap<Integer, Snake>();
+
+	public static synchronized void addSnake(Snake snake) {
+		if (snakes.size() == 0) {
+			startTimer();
+		}
+		snakes.put(Integer.valueOf(snake.getId()), snake);
+	}
+
+	public static Collection<Snake> getSnakes() {
+		return Collections.unmodifiableCollection(snakes.values());
+	}
+
+	public static synchronized void removeSnake(Snake snake) {
+		snakes.remove(Integer.valueOf(snake.getId()));
+		if (snakes.size() == 0) {
+			stopTimer();
+		}
+	}
+
+	public static void tick() throws Exception {
+		StringBuilder sb = new StringBuilder();
+		for (Iterator<Snake> iterator = SnakeTimer.getSnakes().iterator(); iterator
+				.hasNext();) {
+			Snake snake = iterator.next();
+			snake.update(SnakeTimer.getSnakes());
+			sb.append(snake.getLocationsJson());
+			if (iterator.hasNext()) {
+				sb.append(',');
+			}
+		}
+		broadcast(String.format("{'type': 'update', 'data' : [%s]}", sb.toString()));
+	}
+
+	public static void broadcast(String message) throws Exception {
+		Collection<Snake> snakes = new CopyOnWriteArrayList<>(SnakeTimer.getSnakes());
+		for (Snake snake : snakes) {
+			try {
+				snake.sendMessage(message);
+			}
+			catch (Throwable ex) {
+				// if Snake#sendMessage fails the client is removed
+				removeSnake(snake);
+			}
+		}
+	}
+
+	public static void startTimer() {
+		gameTimer = new Timer(SnakeTimer.class.getSimpleName() + " Timer");
+		gameTimer.scheduleAtFixedRate(new TimerTask() {
+			@Override
+			public void run() {
+				try {
+					tick();
+				}
+				catch (Throwable ex) {
+					log.error("Caught to prevent timer from shutting down", ex);
+				}
+			}
+		}, TICK_DELAY, TICK_DELAY);
+	}
+
+	public static void stopTimer() {
+		if (gameTimer != null) {
+			gameTimer.cancel();
+		}
+	}
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/SnakeUtils.java

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+import java.awt.Color;
+import java.util.Random;
+
+public class SnakeUtils {
+
+	public static final int PLAYFIELD_WIDTH = 640;
+	public static final int PLAYFIELD_HEIGHT = 480;
+	public static final int GRID_SIZE = 10;
+
+	private static final Random random = new Random();
+
+	public static String getRandomHexColor() {
+		float hue = random.nextFloat();
+		// sat between 0.1 and 0.3
+		float saturation = (random.nextInt(2000) + 1000) / 10000f;
+		float luminance = 0.9f;
+		Color color = Color.getHSBColor(hue, saturation, luminance);
+		return '#' + Integer.toHexString((color.getRGB() & 0xffffff) | 0x1000000)
+				.substring(1);
+	}
+
+	public static Location getRandomLocation() {
+		int x = roundByGridSize(random.nextInt(PLAYFIELD_WIDTH));
+		int y = roundByGridSize(random.nextInt(PLAYFIELD_HEIGHT));
+		return new Location(x, y);
+	}
+
+	private static int roundByGridSize(int value) {
+		value = value + (GRID_SIZE / 2);
+		value = value / GRID_SIZE;
+		value = value * GRID_SIZE;
+		return value;
+	}
+
+}

spring-boot-samples/spring-boot-sample-websocket-tomcat/src/main/java/samples/websocket/snake/SnakeWebSocketHandler.java

@@ -0,0 +1,112 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package samples.websocket.snake;
+
+import java.awt.Color;
+import java.util.Iterator;
+import java.util.Random;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.springframework.web.socket.CloseStatus;
+import org.springframework.web.socket.TextMessage;
+import org.springframework.web.socket.WebSocketSession;
+import org.springframework.web.socket.handler.TextWebSocketHandler;
+
+public class SnakeWebSocketHandler extends TextWebSocketHandler {
+
+	public static final int PLAYFIELD_WIDTH = 640;
+	public static final int PLAYFIELD_HEIGHT = 480;
+	public static final int GRID_SIZE = 10;
+
+	private static final AtomicInteger snakeIds = new AtomicInteger(0);
+	private static final Random random = new Random();
+
+	private final int id;
+	private Snake snake;
+
+	public static String getRandomHexColor() {
+		float hue = random.nextFloat();
+		// sat between 0.1 and 0.3
+		float saturation = (random.nextInt(2000) + 1000) / 10000f;
+		float luminance = 0.9f;
+		Color color = Color.getHSBColor(hue, saturation, luminance);
+		return '#' + Integer.toHexString((color.getRGB() & 0xffffff) | 0x1000000)
+				.substring(1);
+	}
+
+	public static Location getRandomLocation() {
+		int x = roundByGridSize(random.nextInt(PLAYFIELD_WIDTH));
+		int y = roundByGridSize(random.nextInt(PLAYFIELD_HEIGHT));
+		return new Location(x, y);
+	}
+
+	private static int roundByGridSize(int value) {
+		value = value + (GRID_SIZE / 2);
+		value = value / GRID_SIZE;
+		value = value * GRID_SIZE;
+		return value;
+	}
+
+	public SnakeWebSocketHandler() {
+		this.id = snakeIds.getAndIncrement();
+	}
+
+	@Override
+	public void afterConnectionEstablished(WebSocketSession session) throws Exception {
+		this.snake = new Snake(this.id, session);
+		SnakeTimer.addSnake(this.snake);
+		StringBuilder sb = new StringBuilder();
+		for (Iterator<Snake> iterator = SnakeTimer.getSnakes().iterator(); iterator
+				.hasNext();) {
+			Snake snake = iterator.next();
+			sb.append(String.format("{id: %d, color: '%s'}",
+					Integer.valueOf(snake.getId()), snake.getHexColor()));
+			if (iterator.hasNext()) {
+				sb.append(',');
+			}
+		}
+		SnakeTimer
+				.broadcast(String.format("{'type': 'join','data':[%s]}", sb.toString()));
+	}
+
+	@Override
+	protected void handleTextMessage(WebSocketSession session, TextMessage message)
+			throws Exception {
+		String payload = message.getPayload();
+		if ("west".equals(payload)) {
+			this.snake.setDirection(Direction.WEST);
+		}
+		else if ("north".equals(payload)) {
+			this.snake.setDirection(Direction.NORTH);
+		}
+		else if ("east".equals(payload)) {
+			this.snake.setDirection(Direction.EAST);
+		}
+		else if ("south".equals(payload)) {
+			this.snake.setDirection(Direction.SOUTH);
+		}
+	}
+
+	@Override
+	public void afterConnectionClosed(WebSocketSession session, CloseStatus status)
+			throws Exception {
+		SnakeTimer.removeSnake(this.snake);
+		SnakeTimer.broadcast(String.format("{'type': 'leave', 'id': %d}",
+				Integer.valueOf(this.id)));
+	}
+}