BAEL-4648: How to debug Websockets (#11469)

* BAEL-4648: How to debug Websockets

* Formatted the code

* Incorporated comments from Kevin

spring-websockets/src/main/java/com/baeldung/debugwebsockets/StockTicksController.java

@@ -0,0 +1,39 @@
+package com.baeldung.debugwebsockets;
+
+import org.springframework.messaging.simp.SimpMessagingTemplate;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Controller;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
+
+@Controller
+public class StockTicksController {
+    private final SimpMessagingTemplate simpMessagingTemplate;
+
+    public StockTicksController(SimpMessagingTemplate simpMessagingTemplate) {
+        this.simpMessagingTemplate = simpMessagingTemplate;
+    }
+
+    @Scheduled(fixedRate = 3000)
+    public void sendTicks() {
+        simpMessagingTemplate.convertAndSend("/topic/ticks", getStockTicks());
+    }
+
+    private Map<String, Integer> getStockTicks() {
+        Map<String, Integer> ticks = new HashMap<>();
+        ticks.put("AAPL", getRandomTick());
+        ticks.put("GOOGL", getRandomTick());
+        ticks.put("MSFT", getRandomTick());
+        ticks.put("TSLA", getRandomTick());
+        ticks.put("AMZN", getRandomTick());
+        ticks.put("HPE", getRandomTick());
+
+        return ticks;
+    }
+
+    private int getRandomTick() {
+        return ThreadLocalRandom.current().nextInt(-100, 100 + 1);
+    }
+}

spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompClientSessionHandler.java

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+package com.baeldung.debugwebsockets;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.messaging.simp.stomp.StompHeaders;
+import org.springframework.messaging.simp.stomp.StompSession;
+import org.springframework.messaging.simp.stomp.StompSessionHandlerAdapter;
+
+import java.lang.reflect.Type;
+import java.util.Map;
+
+public class StompClientSessionHandler extends StompSessionHandlerAdapter {
+    private static final Logger logger = LoggerFactory.getLogger("StompClientSessionHandler");
+
+    @Override
+    public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
+        logger.info("New session established. Session Id -> {}", session.getSessionId());
+        session.subscribe("/topic/ticks", this);
+        logger.info("Subscribed to topic: /topic/ticks");
+    }
+
+    @Override
+    public void handleFrame(StompHeaders headers, Object payload) {
+        logger.info("Payload -> {}", payload);
+    }
+
+    @Override
+    public Type getPayloadType(StompHeaders headers) {
+        return Map.class;
+    }
+}

spring-websockets/src/main/java/com/baeldung/debugwebsockets/StompWebSocketClient.java

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+package com.baeldung.debugwebsockets;
+
+import org.springframework.messaging.converter.MappingJackson2MessageConverter;
+import org.springframework.messaging.simp.stomp.StompSessionHandler;
+import org.springframework.web.socket.client.WebSocketClient;
+import org.springframework.web.socket.client.standard.StandardWebSocketClient;
+import org.springframework.web.socket.messaging.WebSocketStompClient;
+
+import java.util.Scanner;
+
+public class StompWebSocketClient {
+
+    private static final String URL = "ws://localhost:8080/stock-ticks/websocket";
+
+    public static void main(String[] args) {
+        WebSocketClient client = new StandardWebSocketClient();
+        WebSocketStompClient stompClient = new WebSocketStompClient(client);
+        stompClient.setMessageConverter(new MappingJackson2MessageConverter());
+        StompSessionHandler sessionHandler = new StompClientSessionHandler();
+        stompClient.connect(URL, sessionHandler);
+
+        new Scanner(System.in).nextLine();
+    }
+}

spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketApplication.java

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+package com.baeldung.debugwebsockets;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class WebsocketApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(WebsocketApplication.class, args);
+    }
+
+}

spring-websockets/src/main/java/com/baeldung/debugwebsockets/WebsocketConfiguration.java

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+package com.baeldung.debugwebsockets;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.messaging.simp.config.MessageBrokerRegistry;
+import org.springframework.scheduling.annotation.EnableScheduling;
+import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
+import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
+import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
+
+@Configuration
+@EnableWebSocketMessageBroker
+@EnableScheduling
+public class WebsocketConfiguration implements WebSocketMessageBrokerConfigurer {
+    @Override
+    public void configureMessageBroker(MessageBrokerRegistry config) {
+        config.enableSimpleBroker("/topic");
+        config.setApplicationDestinationPrefixes("/app");
+    }
+
+    @Override
+    public void registerStompEndpoints(StompEndpointRegistry registry) {
+        registry.addEndpoint("/stock-ticks").setAllowedOriginPatterns("*").withSockJS();
+    }
+
+}

spring-websockets/src/test/java/com/baeldung/debugwebsockets/WebSocketIntegrationTest.java

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+package com.baeldung.debugwebsockets;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.messaging.converter.MappingJackson2MessageConverter;
+import org.springframework.messaging.simp.stomp.StompCommand;
+import org.springframework.messaging.simp.stomp.StompFrameHandler;
+import org.springframework.messaging.simp.stomp.StompHeaders;
+import org.springframework.messaging.simp.stomp.StompSession;
+import org.springframework.messaging.simp.stomp.StompSessionHandler;
+import org.springframework.web.socket.client.WebSocketClient;
+import org.springframework.web.socket.client.standard.StandardWebSocketClient;
+import org.springframework.web.socket.messaging.WebSocketStompClient;
+
+import java.lang.reflect.Type;
+import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+/**
+ * This should be part of integration test suite.
+ * The test starts the server and then connects to the WebSocket. Then verifies if the messages are received from the
+ * WebSocket.
+ * This test is inspired from: https://github.com/spring-guides/gs-messaging-stomp-websocket/blob/main/complete/src/test/java/com/example/messagingstompwebsocket/GreetingIntegrationTests.java
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class WebSocketIntegrationTest{
+    WebSocketClient client;
+    WebSocketStompClient stompClient;
+    @LocalServerPort
+    private int port;
+    private static final Logger logger= LoggerFactory.getLogger(WebSocketIntegrationTest.class);
+
+    @BeforeEach
+    public void setup() {
+        logger.info("Setting up the tests ...");
+        client = new StandardWebSocketClient();
+        stompClient = new WebSocketStompClient(client);
+        stompClient.setMessageConverter(new MappingJackson2MessageConverter());
+    }
+
+    @Test
+    void givenWebSocket_whenMessage_thenVerifyMessage() throws Exception {
+        final CountDownLatch latch = new CountDownLatch(1);
+        final AtomicReference<Throwable> failure = new AtomicReference<>();
+        StompSessionHandler sessionHandler = new StompSessionHandler() {
+            @Override
+            public Type getPayloadType(StompHeaders headers) {
+                return null;
+            }
+
+            @Override
+            public void handleFrame(StompHeaders headers, Object payload) {
+            }
+
+            @Override
+            public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
+                logger.info("Connected to the WebSocket ...");
+                session.subscribe("/topic/ticks", new StompFrameHandler() {
+                    @Override
+                    public Type getPayloadType(StompHeaders headers) {
+                        return Map.class;
+                    }
+
+                    @Override
+                    public void handleFrame(StompHeaders headers, Object payload) {
+                        try {
+
+                            assertThat(payload).isNotNull();
+                            assertThat(payload).isInstanceOf(Map.class);
+
+                            @SuppressWarnings("unchecked")
+                            Map<String, Integer> map = (Map<String, Integer>) payload;
+
+                            assertThat(map).containsKey("HPE");
+                            assertThat(map.get("HPE")).isInstanceOf(Integer.class);
+                        } catch (Throwable t) {
+                            failure.set(t);
+                            logger.error("There is an exception ", t);
+                        } finally {
+                            session.disconnect();
+                            latch.countDown();
+                        }
+
+                    }
+                });
+            }
+
+            @Override
+            public void handleException(StompSession session, StompCommand command, StompHeaders headers, byte[] payload, Throwable exception) {
+            }
+
+            @Override
+            public void handleTransportError(StompSession session, Throwable exception) {
+            }
+        };
+        stompClient.connect("ws://localhost:{port}/stock-ticks/websocket", sessionHandler, this.port);
+        if (latch.await(20, TimeUnit.SECONDS)) {
+            if (failure.get() != null) {
+                fail("Assertion Failed", failure.get());
+            }
+        } else {
+            fail("Could not receive the message on time");
+        }
+    }
+}