GH-3533: Register WebSocket endpoints at runtime (#3548)

* GH-3533: Register WebSocket endpoints at runtime

Fixes https://github.com/spring-projects/spring-integration/issues/3533

* Rework `WebSocketIntegrationConfigurationInitializer` to register beans functional way
to avoid reflection for Spring Native support
* Move `IntegrationServletWebSocketHandlerRegistry` into a separate file for better readability
* Implement `DestructionAwareBeanPostProcessor` for `IntegrationServletWebSocketHandlerRegistry`
to track runtime bean registrations and removals
* Introduce an `IntegrationDynamicWebSocketHandlerMapping` to manage runtime mapping
registrations and removals
* Add `servlet-api` dependency into `websocket` to be able to compile an
`IntegrationDynamicWebSocketHandlerMapping`
* Fix typo in the exception message of the `StandardIntegrationFlowRegistration`
* Start dynamically added beans together with associated `IntegrationFlow` in the
`StandardIntegrationFlowContext`
* Document new feature

* * Fix language in docs
* Don't start those `SmartLifecycle`s together with a dynamic flow
which are not `isAutoStartup()`

* * Fix `TomcatWebSocketTestServer` to configure servlet for `loadOnStartup = 1`
* Fix `WebSocketDslTests` to make `clientWebSocketContainer.setAutoStartup(true)`

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/IntegrationWebSocketContainer.java

@@ -104,6 +104,10 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 		}
 	}
 
+	public WebSocketHandler getWebSocketHandler() {
+		return this.webSocketHandler;
+	}
+
 	public List<String> getSubProtocols() {
 		List<String> protocols = new ArrayList<>();
 		if (this.messageListener != null) {

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/config/IntegrationDynamicWebSocketHandlerMapping.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 org.springframework.integration.websocket.config;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.web.HttpRequestHandler;
+import org.springframework.web.servlet.HandlerExecutionChain;
+import org.springframework.web.servlet.handler.AbstractHandlerMapping;
+
+/**
+ * The {@link AbstractHandlerMapping} implementation for dynamic WebSocket endpoint registrations in Spring Integration.
+ * <p>
+ * TODO until https://github.com/spring-projects/spring-framework/issues/26798
+ *
+ * @author Artem Bilan
+ *
+ * @since 5.5
+ */
+class IntegrationDynamicWebSocketHandlerMapping extends AbstractHandlerMapping {
+
+	private final Map<String, HttpRequestHandler> handlerMap = new HashMap<>();
+
+	@Override
+	protected Object getHandlerInternal(HttpServletRequest request) {
+		String lookupPath = initLookupPath(request);
+		HttpRequestHandler httpRequestHandler = this.handlerMap.get(lookupPath);
+		return httpRequestHandler != null ? new HandlerExecutionChain(httpRequestHandler) : null;
+	}
+
+	void registerHandler(String path, HttpRequestHandler httpHandler) {
+		this.handlerMap.put(path, httpHandler);
+	}
+
+	void unregisterHandler(String path) {
+		this.handlerMap.remove(path);
+	}
+
+}

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/config/IntegrationServletWebSocketHandlerRegistry.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 org.springframework.integration.websocket.config;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.integration.websocket.ServerWebSocketContainer;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.HttpRequestHandler;
+import org.springframework.web.servlet.handler.AbstractHandlerMapping;
+import org.springframework.web.socket.WebSocketHandler;
+import org.springframework.web.socket.config.annotation.ServletWebSocketHandlerRegistration;
+import org.springframework.web.socket.config.annotation.ServletWebSocketHandlerRegistry;
+import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistration;
+
+/**
+ * The {@link ServletWebSocketHandlerRegistry} extension for Spring Integration purpose, especially
+ * a dynamic WebSocket endpoint registrations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 5.5
+ */
+class IntegrationServletWebSocketHandlerRegistry extends ServletWebSocketHandlerRegistry
+		implements ApplicationContextAware, DestructionAwareBeanPostProcessor {
+
+	private final Map<WebSocketHandler, List<String>> dynamicRegistrations = new HashMap<>();
+
+	private ApplicationContext applicationContext;
+
+	private volatile IntegrationDynamicWebSocketHandlerMapping dynamicHandlerMapping;
+
+	IntegrationServletWebSocketHandlerRegistry() {
+	}
+
+	@Override
+	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+		this.applicationContext = applicationContext;
+	}
+
+
+	@Override
+	protected boolean requiresTaskScheduler() { // NOSONAR visibility
+		return super.requiresTaskScheduler();
+	}
+
+	@Override
+	protected void setTaskScheduler(TaskScheduler scheduler) { // NOSONAR visibility
+		super.setTaskScheduler(scheduler);
+	}
+
+	@Override
+	public AbstractHandlerMapping getHandlerMapping() {
+		AbstractHandlerMapping originHandlerMapping = super.getHandlerMapping();
+		originHandlerMapping.setApplicationContext(this.applicationContext);
+		this.dynamicHandlerMapping = this.applicationContext.getBean(IntegrationDynamicWebSocketHandlerMapping.class);
+		return originHandlerMapping;
+	}
+
+	@Override
+	public WebSocketHandlerRegistration addHandler(WebSocketHandler handler, String... paths) {
+		if (this.dynamicHandlerMapping != null) {
+			IntegrationDynamicWebSocketHandlerRegistration registration =
+					new IntegrationDynamicWebSocketHandlerRegistration();
+			registration.addHandler(handler, paths);
+			MultiValueMap<HttpRequestHandler, String> mappings = registration.getMapping();
+			for (Map.Entry<HttpRequestHandler, List<String>> entry : mappings.entrySet()) {
+				HttpRequestHandler httpHandler = entry.getKey();
+				List<String> patterns = entry.getValue();
+				this.dynamicRegistrations.put(handler, patterns);
+				for (String pattern : patterns) {
+					this.dynamicHandlerMapping.registerHandler(pattern, httpHandler);
+				}
+			}
+			return registration;
+		}
+		else {
+			return super.addHandler(handler, paths);
+		}
+	}
+
+	@Override
+	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
+		if (this.dynamicHandlerMapping != null && bean instanceof ServerWebSocketContainer) {
+			((ServerWebSocketContainer) bean).registerWebSocketHandlers(this);
+		}
+		return bean;
+	}
+
+	@Override
+	public boolean requiresDestruction(Object bean) {
+		return bean instanceof ServerWebSocketContainer;
+	}
+
+	@Override
+	public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
+		if (requiresDestruction(bean)) {
+			removeRegistration((ServerWebSocketContainer) bean);
+		}
+	}
+
+	void removeRegistration(ServerWebSocketContainer serverWebSocketContainer) {
+		List<String> patterns = this.dynamicRegistrations.remove(serverWebSocketContainer.getWebSocketHandler());
+		if (this.dynamicHandlerMapping != null && !CollectionUtils.isEmpty(patterns)) {
+			for (String pattern : patterns) {
+				this.dynamicHandlerMapping.unregisterHandler(pattern);
+			}
+		}
+	}
+
+	private static final class IntegrationDynamicWebSocketHandlerRegistration
+			extends ServletWebSocketHandlerRegistration {
+
+		MultiValueMap<HttpRequestHandler, String> getMapping() {
+			return getMappings();
+		}
+
+	}
+
+}

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/config/WebSocketIntegrationConfigurationInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2021 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.
@@ -26,17 +26,14 @@ import org.springframework.beans.factory.config.AbstractFactoryBean;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
-import org.springframework.context.ApplicationContext;
-import org.springframework.context.ApplicationContextAware;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.integration.config.IntegrationConfigurationInitializer;
-import org.springframework.scheduling.TaskScheduler;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
 import org.springframework.util.ClassUtils;
 import org.springframework.web.servlet.HandlerMapping;
-import org.springframework.web.servlet.handler.AbstractHandlerMapping;
 import org.springframework.web.socket.config.annotation.DelegatingWebSocketConfiguration;
-import org.springframework.web.socket.config.annotation.ServletWebSocketHandlerRegistry;
 import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
 
 /**
@@ -60,7 +57,7 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 	@Override
 	public void initialize(ConfigurableListableBeanFactory beanFactory) throws BeansException {
 		if (beanFactory instanceof BeanDefinitionRegistry) {
-			this.registerEnableWebSocketIfNecessary((BeanDefinitionRegistry) beanFactory);
+			registerEnableWebSocketIfNecessary((BeanDefinitionRegistry) beanFactory);
 		}
 		else {
 			LOGGER.warn("'DelegatingWebSocketConfiguration' isn't registered because 'beanFactory'" +
@@ -87,22 +84,30 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 	private void registerEnableWebSocketIfNecessary(BeanDefinitionRegistry registry) {
 		if (SERVLET_PRESENT) {
 			if (!registry.containsBeanDefinition("defaultSockJsTaskScheduler")) {
-				BeanDefinitionBuilder sockJsTaskSchedulerBuilder =
-						BeanDefinitionBuilder.genericBeanDefinition(ThreadPoolTaskScheduler.class)
-								.addPropertyValue("threadNamePrefix", "SockJS-")
-								.addPropertyValue("poolSize", Runtime.getRuntime().availableProcessors())
-								.addPropertyValue("removeOnCancelPolicy", true);
-
+				ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
+				taskScheduler.setThreadNamePrefix("SockJS-");
+				taskScheduler.setPoolSize(Runtime.getRuntime().availableProcessors());
+				taskScheduler.setRemoveOnCancelPolicy(true);
 				registry.registerBeanDefinition("defaultSockJsTaskScheduler",
-						sockJsTaskSchedulerBuilder.getBeanDefinition());
+						new RootBeanDefinition(ThreadPoolTaskScheduler.class, () -> taskScheduler));
 			}
 
 			if (!registry.containsBeanDefinition(DelegatingWebSocketConfiguration.class.getName()) &&
 					!registry.containsBeanDefinition(WEB_SOCKET_HANDLER_MAPPING_BEAN_NAME)) {
+
+				registry.registerBeanDefinition("integrationServletWebSocketHandlerRegistry",
+						new RootBeanDefinition(IntegrationServletWebSocketHandlerRegistry.class,
+								IntegrationServletWebSocketHandlerRegistry::new));
+
+				BeanDefinitionReaderUtils.registerWithGeneratedName(
+						new RootBeanDefinition(IntegrationDynamicWebSocketHandlerMapping.class,
+								IntegrationDynamicWebSocketHandlerMapping::new),
+						registry);
+
 				BeanDefinitionBuilder enableWebSocketBuilder =
-						BeanDefinitionBuilder.genericBeanDefinition(WebSocketHandlerMappingFactoryBean.class)
-								.setRole(BeanDefinition.ROLE_INFRASTRUCTURE)
-								.addPropertyReference("sockJsTaskScheduler", "defaultSockJsTaskScheduler");
+						BeanDefinitionBuilder.genericBeanDefinition(WebSocketHandlerMappingFactoryBean.class,
+								() -> createWebSocketHandlerMapping((BeanFactory) registry))
+								.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 
 				registry.registerBeanDefinition(WEB_SOCKET_HANDLER_MAPPING_BEAN_NAME,
 						enableWebSocketBuilder.getBeanDefinition());
@@ -110,25 +115,22 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 		}
 	}
 
-	private static class WebSocketHandlerMappingFactoryBean extends AbstractFactoryBean<HandlerMapping>
-			implements ApplicationContextAware {
+	private static WebSocketHandlerMappingFactoryBean createWebSocketHandlerMapping(BeanFactory beanFactory) {
+		WebSocketHandlerMappingFactoryBean mappingFactoryBean = new WebSocketHandlerMappingFactoryBean();
+		mappingFactoryBean.registry =
+				beanFactory.getBean("integrationServletWebSocketHandlerRegistry",
+						IntegrationServletWebSocketHandlerRegistry.class);
+		mappingFactoryBean.sockJsTaskScheduler =
+				beanFactory.getBean("defaultSockJsTaskScheduler", ThreadPoolTaskScheduler.class);
+		return mappingFactoryBean;
+	}
 
-		private final IntegrationServletWebSocketHandlerRegistry registry =
-				new IntegrationServletWebSocketHandlerRegistry();
+	private static class WebSocketHandlerMappingFactoryBean extends AbstractFactoryBean<HandlerMapping> {
+
+		private IntegrationServletWebSocketHandlerRegistry registry;
 
 		private ThreadPoolTaskScheduler sockJsTaskScheduler;
 
-		private ApplicationContext applicationContext;
-
-		public void setSockJsTaskScheduler(ThreadPoolTaskScheduler sockJsTaskScheduler) {
-			this.sockJsTaskScheduler = sockJsTaskScheduler;
-		}
-
-		@Override
-		public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
-			this.applicationContext = applicationContext;
-		}
-
 		@Override
 		protected HandlerMapping createInstance() {
 			BeanFactory beanFactory = getBeanFactory();
@@ -141,9 +143,7 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 			if (this.registry.requiresTaskScheduler()) {
 				this.registry.setTaskScheduler(this.sockJsTaskScheduler);
 			}
-			AbstractHandlerMapping handlerMapping = this.registry.getHandlerMapping();
-			handlerMapping.setApplicationContext(this.applicationContext);
-			return handlerMapping;
+			return this.registry.getHandlerMapping();
 		}
 
 		@Override
@@ -153,21 +153,4 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 
 	}
 
-	private static class IntegrationServletWebSocketHandlerRegistry extends ServletWebSocketHandlerRegistry {
-
-		IntegrationServletWebSocketHandlerRegistry() {
-		}
-
-		@Override
-		public boolean requiresTaskScheduler() { // NOSONAR visibility
-			return super.requiresTaskScheduler();
-		}
-
-		@Override
-		public void setTaskScheduler(TaskScheduler scheduler) { // NOSONAR visibility
-			super.setTaskScheduler(scheduler);
-		}
-
-	}
-
 }

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/inbound/WebSocketInboundChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2020 the original author or authors.
+ * Copyright 2014-2021 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.
@@ -280,7 +280,7 @@ public class WebSocketInboundChannelAdapter extends MessageProducerSupport
 	public boolean isActive() {
 		boolean active = super.isActive();
 		if (!active) {
-			logger.warn("MessageProducer '" + this + "' isn't started to accept WebSocket events.");
+			logger.warn(() -> "MessageProducer '" + this + "' isn't started to accept WebSocket events.");
 		}
 		return active;
 	}
@@ -308,8 +308,8 @@ public class WebSocketInboundChannelAdapter extends MessageProducerSupport
 			if (this.useBroker) {
 				this.brokerHandler.handleMessage(message);
 			}
-			else if (logger.isDebugEnabled()) {
-				logger.debug("Messages with non 'SimpMessageType.MESSAGE' type are ignored for sending to the " +
+			else {
+				logger.debug(() -> "Messages with non 'SimpMessageType.MESSAGE' type are ignored for sending to the " +
 						"'outputChannel'. They have to be emitted as 'ApplicationEvent's " +
 						"from the 'SubProtocolHandler'. Or using 'AbstractBrokerMessageHandler'(useBroker = true) " +
 						"from server side. Received message: " + message);

spring-integration-websocket/src/test/java/org/springframework/integration/websocket/TomcatWebSocketTestServer.java

@@ -20,6 +20,7 @@ import java.io.File;
 import java.io.IOException;
 
 import org.apache.catalina.Context;
+import org.apache.catalina.Wrapper;
 import org.apache.catalina.startup.Tomcat;
 import org.apache.tomcat.websocket.server.WsContextListener;
 
@@ -49,8 +50,10 @@ public class TomcatWebSocketTestServer implements InitializingBean, DisposableBe
 
 		Context context = this.tomcatServer.addContext("", System.getProperty("java.io.tmpdir"));
 		context.addApplicationListener(WsContextListener.class.getName());
-		Tomcat.addServlet(context, "dispatcherServlet", new DispatcherServlet(this.serverContext))
-				.setAsyncSupported(true);
+		Wrapper dispatcherServlet =
+				Tomcat.addServlet(context, "dispatcherServlet", new DispatcherServlet(this.serverContext));
+		dispatcherServlet.setAsyncSupported(true);
+		dispatcherServlet.setLoadOnStartup(1);
 		context.addServletMappingDecoded("/", "dispatcherServlet");
 	}
 

spring-integration-websocket/src/test/java/org/springframework/integration/websocket/dsl/WebSocketDslTests.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 org.springframework.integration.websocket.dsl;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import javax.websocket.DeploymentException;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+import org.springframework.integration.dsl.IntegrationFlows;
+import org.springframework.integration.dsl.context.IntegrationFlowContext;
+import org.springframework.integration.websocket.ClientWebSocketContainer;
+import org.springframework.integration.websocket.ServerWebSocketContainer;
+import org.springframework.integration.websocket.TomcatWebSocketTestServer;
+import org.springframework.integration.websocket.inbound.WebSocketInboundChannelAdapter;
+import org.springframework.integration.websocket.outbound.WebSocketOutboundMessageHandler;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHandlingException;
+import org.springframework.messaging.support.GenericMessage;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.socket.client.WebSocketClient;
+import org.springframework.web.socket.client.standard.StandardWebSocketClient;
+import org.springframework.web.socket.server.HandshakeHandler;
+import org.springframework.web.socket.server.standard.TomcatRequestUpgradeStrategy;
+import org.springframework.web.socket.server.support.DefaultHandshakeHandler;
+
+@SpringJUnitConfig(classes = WebSocketDslTests.ClientConfig.class)
+@DirtiesContext
+public class WebSocketDslTests {
+
+	@Autowired
+	TomcatWebSocketTestServer server;
+
+	@Autowired
+	WebSocketClient webSocketClient;
+
+	@Autowired
+	IntegrationFlowContext integrationFlowContext;
+
+	@Test
+	void testDynamicServerEndpointRegistration() {
+		// Dynamic server flow
+		AnnotationConfigWebApplicationContext serverContext = this.server.getServerContext();
+		IntegrationFlowContext serverIntegrationFlowContext = serverContext.getBean(IntegrationFlowContext.class);
+		ServerWebSocketContainer serverWebSocketContainer =
+				new ServerWebSocketContainer("/dynamic")
+						.setHandshakeHandler(serverContext.getBean(HandshakeHandler.class));
+
+		WebSocketInboundChannelAdapter webSocketInboundChannelAdapter =
+				new WebSocketInboundChannelAdapter(serverWebSocketContainer);
+
+		QueueChannel dynamicRequestsChannel = new QueueChannel();
+
+		IntegrationFlow serverFlow =
+				IntegrationFlows.from(webSocketInboundChannelAdapter)
+						.channel(dynamicRequestsChannel)
+						.get();
+
+		IntegrationFlowContext.IntegrationFlowRegistration dynamicServerFlow =
+				serverIntegrationFlowContext.registration(serverFlow)
+						.addBean(serverWebSocketContainer)
+						.register();
+
+		// Dynamic client flow
+		ClientWebSocketContainer clientWebSocketContainer =
+				new ClientWebSocketContainer(this.webSocketClient, this.server.getWsBaseUrl() + "/dynamic");
+		clientWebSocketContainer.setAutoStartup(true);
+		WebSocketOutboundMessageHandler webSocketOutboundMessageHandler =
+				new WebSocketOutboundMessageHandler(clientWebSocketContainer);
+
+		IntegrationFlow clientFlow = flow -> flow.handle(webSocketOutboundMessageHandler);
+
+		IntegrationFlowContext.IntegrationFlowRegistration dynamicClientFlow =
+				this.integrationFlowContext.registration(clientFlow)
+						.addBean(clientWebSocketContainer)
+						.register();
+
+		dynamicClientFlow.getInputChannel().send(new GenericMessage<>("dynamic test"));
+
+		Message<?> result = dynamicRequestsChannel.receive(10_000);
+		assertThat(result).isNotNull()
+				.extracting(Message::getPayload)
+				.isEqualTo("dynamic test");
+
+		dynamicServerFlow.destroy();
+
+		assertThatExceptionOfType(MessageHandlingException.class)
+				.isThrownBy(() -> dynamicClientFlow.getInputChannel().send(new GenericMessage<>("another test")))
+				.withCauseInstanceOf(DeploymentException.class)
+				.withMessageContaining("The HTTP response from the server [404]");
+
+		dynamicClientFlow.destroy();
+	}
+
+	@Configuration
+	@EnableIntegration
+	public static class ClientConfig {
+
+		@Bean
+		public TomcatWebSocketTestServer server() {
+			return new TomcatWebSocketTestServer(WebSocketDslTests.ServerConfig.class);
+		}
+
+		@Bean
+		public WebSocketClient webSocketClient() {
+			return new StandardWebSocketClient();
+		}
+
+	}
+
+
+	@Configuration
+	@EnableIntegration
+	static class ServerConfig {
+
+		@Bean
+		public DefaultHandshakeHandler handshakeHandler() {
+			return new DefaultHandshakeHandler(new TomcatRequestUpgradeStrategy());
+		}
+
+	}
+
+}