Add reactive web server infrastructure

This commit adds the infrastructure for creating and customizing
reactive embedded web servers. Common configuration has been refactored
into the new `ConfigurableEmbeddedWebServer` interface.

See gh-8302

spring-boot-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -112,6 +112,7 @@ org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguratio
 org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration,\
+org.springframework.boot.autoconfigure.webflux.ReactiveWebServerAutoConfiguration,\
 org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration,\
 org.springframework.boot.autoconfigure.websocket.WebSocketMessagingAutoConfiguration,\
 org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration

spring-boot/src/main/java/org/springframework/boot/context/embedded/AbstractConfigurableReactiveWebServer.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+import java.net.InetAddress;
+import java.util.Arrays;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+import org.springframework.boot.web.servlet.ErrorPage;
+import org.springframework.util.Assert;
+
+/**
+ * Abstract base class for {@link ConfigurableReactiveWebServer} implementations.
+ *
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+public class AbstractConfigurableReactiveWebServer implements ConfigurableReactiveWebServer {
+
+	private int port = 8080;
+
+	private Set<ErrorPage> errorPages = new LinkedHashSet<ErrorPage>();
+
+	private InetAddress address;
+
+	private Ssl ssl;
+
+	private SslStoreProvider sslStoreProvider;
+
+	private Compression compression;
+
+	private String serverHeader;
+
+	/**
+	 * Create a new {@link AbstractConfigurableReactiveWebServer} instance.
+	 */
+	public AbstractConfigurableReactiveWebServer() {
+	}
+
+	/**
+	 * Create a new {@link AbstractConfigurableReactiveWebServer} instance with the
+	 * specified port.
+	 * @param port the port number for the reactive web server
+	 */
+	public AbstractConfigurableReactiveWebServer(int port) {
+		this.port = port;
+	}
+
+	@Override
+	public void setAddress(InetAddress address) {
+		this.address = address;
+	}
+
+	/**
+	 * Return the address that the reactive web server binds to.
+	 * @return the address
+	 */
+	public InetAddress getAddress() {
+		return this.address;
+	}
+
+	@Override
+	public void setPort(int port) {
+		this.port = port;
+	}
+
+	/**
+	 * The port that the reactive web server listens on.
+	 * @return the port
+	 */
+	public int getPort() {
+		return this.port;
+	}
+
+	@Override
+	public void setErrorPages(Set<? extends ErrorPage> errorPages) {
+		Assert.notNull(errorPages, "ErrorPages must not be null");
+		this.errorPages = new LinkedHashSet<ErrorPage>(errorPages);
+	}
+
+	@Override
+	public void addErrorPages(ErrorPage... errorPages) {
+		Assert.notNull(errorPages, "ErrorPages must not be null");
+		this.errorPages.addAll(Arrays.asList(errorPages));
+	}
+
+	/**
+	 * Return a mutable set of {@link ErrorPage ErrorPages} that will be used when
+	 * handling exceptions.
+	 * @return the error pages
+	 */
+	public Set<ErrorPage> getErrorPages() {
+		return this.errorPages;
+	}
+
+	@Override
+	public void setSsl(Ssl ssl) {
+		this.ssl = ssl;
+	}
+
+	public Ssl getSsl() {
+		return this.ssl;
+	}
+
+	@Override
+	public void setSslStoreProvider(SslStoreProvider sslStoreProvider) {
+		this.sslStoreProvider = sslStoreProvider;
+	}
+
+	public SslStoreProvider getSslStoreProvider() {
+		return this.sslStoreProvider;
+	}
+
+	public Compression getCompression() {
+		return this.compression;
+	}
+
+	@Override
+	public void setCompression(Compression compression) {
+		this.compression = compression;
+	}
+
+	public String getServerHeader() {
+		return this.serverHeader;
+	}
+
+	@Override
+	public void setServerHeader(String serverHeader) {
+		this.serverHeader = serverHeader;
+	}
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/AbstractReactiveWebServerFactory.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+/**
+ * Abstract base class for {@link ReactiveWebServerFactory} implementations.
+ *
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+public abstract class AbstractReactiveWebServerFactory
+		extends AbstractConfigurableReactiveWebServer
+		implements ReactiveWebServerFactory {
+
+	public AbstractReactiveWebServerFactory() {
+	}
+
+	public AbstractReactiveWebServerFactory(int port) {
+		super(port);
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/ConfigurableEmbeddedServletContainer.java

@@ -17,16 +17,12 @@
 package org.springframework.boot.context.embedded;
 
 import java.io.File;
-import java.net.InetAddress;
 import java.nio.charset.Charset;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
-import org.springframework.boot.web.servlet.ErrorPage;
-import org.springframework.boot.web.servlet.ErrorPageRegistry;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
 
 /**
@@ -41,7 +37,7 @@ import org.springframework.boot.web.servlet.ServletContextInitializer;
  * @see EmbeddedServletContainerFactory
  * @see EmbeddedServletContainerCustomizer
  */
-public interface ConfigurableEmbeddedServletContainer extends ErrorPageRegistry {
+public interface ConfigurableEmbeddedServletContainer extends ConfigurableEmbeddedWebServer {
 
 	/**
 	 * Sets the context path for the embedded servlet container. The context should start
@@ -59,14 +55,6 @@ public interface ConfigurableEmbeddedServletContainer extends ErrorPageRegistry
 	 */
 	void setDisplayName(String displayName);
 
-	/**
-	 * Sets the port that the embedded servlet container should listen on. If not
-	 * specified port '8080' will be used. Use port -1 to disable auto-start (i.e start
-	 * the web application context but not have it listen to any port).
-	 * @param port the port to set
-	 */
-	void setPort(int port);
-
 	/**
 	 * The session timeout in seconds (default 30 minutes). If 0 or negative then sessions
 	 * never expire.
@@ -94,12 +82,6 @@ public interface ConfigurableEmbeddedServletContainer extends ErrorPageRegistry
 	 */
 	void setSessionStoreDir(File sessionStoreDir);
 
-	/**
-	 * Sets the specific network address that the server should bind to.
-	 * @param address the address to set (defaults to {@code null})
-	 */
-	void setAddress(InetAddress address);
-
 	/**
 	 * Set if the DefaultServlet should be registered. Defaults to {@code true} so that
 	 * files from the {@link #setDocumentRoot(File) document root} will be served.
@@ -107,12 +89,6 @@ public interface ConfigurableEmbeddedServletContainer extends ErrorPageRegistry
 	 */
 	void setRegisterDefaultServlet(boolean registerDefaultServlet);
 
-	/**
-	 * Sets the error pages that will be used when handling exceptions.
-	 * @param errorPages the error pages
-	 */
-	void setErrorPages(Set<? extends ErrorPage> errorPages);
-
 	/**
 	 * Sets the mime-type mappings.
 	 * @param mimeMappings the mime type mappings (defaults to
@@ -146,38 +122,12 @@ public interface ConfigurableEmbeddedServletContainer extends ErrorPageRegistry
 	 */
 	void addInitializers(ServletContextInitializer... initializers);
 
-	/**
-	 * Sets the SSL configuration that will be applied to the container's default
-	 * connector.
-	 * @param ssl the SSL configuration
-	 */
-	void setSsl(Ssl ssl);
-
-	/**
-	 * Sets a provider that will be used to obtain SSL stores.
-	 * @param sslStoreProvider the SSL store provider
-	 */
-	void setSslStoreProvider(SslStoreProvider sslStoreProvider);
-
 	/**
 	 * Sets the configuration that will be applied to the container's JSP servlet.
 	 * @param jsp the JSP servlet configuration
 	 */
 	void setJsp(Jsp jsp);
 
-	/**
-	 * Sets the compression configuration that will be applied to the container's default
-	 * connector.
-	 * @param compression the compression configuration
-	 */
-	void setCompression(Compression compression);
-
-	/**
-	 * Sets the server header value.
-	 * @param serverHeader the server header value
-	 */
-	void setServerHeader(String serverHeader);
-
 	/**
 	 * Sets the Locale to Charset mappings.
 	 * @param localeCharsetMappings the Locale to Charset mappings

spring-boot/src/main/java/org/springframework/boot/context/embedded/ConfigurableEmbeddedWebServer.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+import java.net.InetAddress;
+import java.util.Set;
+
+import org.springframework.boot.web.servlet.ErrorPage;
+import org.springframework.boot.web.servlet.ErrorPageRegistry;
+
+/**
+ * Interface that regroups common customizations to
+ * embedded server factories such as {@link EmbeddedServletContainerFactory}
+ * and {@link ReactiveWebServerFactory}.
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+public interface ConfigurableEmbeddedWebServer extends ErrorPageRegistry {
+
+	/**
+	 * Sets the port that the embedded servlet container should listen on. If not
+	 * specified port '8080' will be used. Use port -1 to disable auto-start (i.e start
+	 * the web application context but not have it listen to any port).
+	 * @param port the port to set
+	 */
+	void setPort(int port);
+
+	/**
+	 * Sets the specific network address that the server should bind to.
+	 * @param address the address to set (defaults to {@code null})
+	 */
+	void setAddress(InetAddress address);
+
+	/**
+	 * Sets the error pages that will be used when handling exceptions.
+	 * @param errorPages the error pages
+	 */
+	void setErrorPages(Set<? extends ErrorPage> errorPages);
+
+	/**
+	 * Sets the SSL configuration that will be applied to the container's default
+	 * connector.
+	 * @param ssl the SSL configuration
+	 */
+	void setSsl(Ssl ssl);
+
+	/**
+	 * Sets a provider that will be used to obtain SSL stores.
+	 * @param sslStoreProvider the SSL store provider
+	 */
+	void setSslStoreProvider(SslStoreProvider sslStoreProvider);
+
+	/**
+	 * Sets the compression configuration that will be applied to the container's default
+	 * connector.
+	 * @param compression the compression configuration
+	 */
+	void setCompression(Compression compression);
+
+	/**
+	 * Sets the server header value.
+	 * @param serverHeader the server header value
+	 */
+	void setServerHeader(String serverHeader);
+
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/ConfigurableReactiveWebServer.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+/**
+ * Interface that represents customizations to a {@link ReactiveWebServerFactory}.
+ *
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+public interface ConfigurableReactiveWebServer extends ConfigurableEmbeddedWebServer {
+
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/ReactiveWebServerCustomizer.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+/**
+ * Strategy interface for customizing auto-configured embedded reactive servers. Any
+ * beans of this type will get a callback with the server factory before the server
+ * itself is started, so you can set the port, address, error pages etc.
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+@FunctionalInterface
+public interface ReactiveWebServerCustomizer {
+
+	/**
+	 * Customize the specified {@link ConfigurableReactiveWebServer}.
+	 * @param server the server to customize
+	 */
+	void customize(ConfigurableReactiveWebServer server);
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/ReactiveWebServerCustomizerBeanPostProcessor.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+
+/**
+ * {@link BeanPostProcessor} that applies all {@link ReactiveWebServerCustomizer}s
+ * from the bean factory to {@link ConfigurableReactiveWebServer} beans.
+ *
+ *
+ * @author Brian Clozel
+ */
+public class ReactiveWebServerCustomizerBeanPostProcessor
+		implements BeanPostProcessor, ApplicationContextAware {
+
+	private ApplicationContext applicationContext;
+
+	private List<ReactiveWebServerCustomizer> customizers;
+
+	@Override
+	public void setApplicationContext(ApplicationContext applicationContext)
+			throws BeansException {
+		this.applicationContext = applicationContext;
+	}
+
+	@Override
+	public Object postProcessBeforeInitialization(Object bean, String beanName)
+			throws BeansException {
+		if (bean instanceof ConfigurableReactiveWebServer) {
+			postProcessBeforeInitialization((ConfigurableReactiveWebServer) bean);
+		}
+		return bean;
+	}
+
+	@Override
+	public Object postProcessAfterInitialization(Object bean, String beanName)
+			throws BeansException {
+		return bean;
+	}
+
+	private void postProcessBeforeInitialization(
+			ConfigurableReactiveWebServer bean) {
+		for (ReactiveWebServerCustomizer customizer : getCustomizers()) {
+			customizer.customize(bean);
+		}
+	}
+
+	private Collection<ReactiveWebServerCustomizer> getCustomizers() {
+		if (this.customizers == null) {
+			// Look up does not include the parent context
+			this.customizers = new ArrayList<ReactiveWebServerCustomizer>(
+					this.applicationContext
+							.getBeansOfType(ReactiveWebServerCustomizer.class,
+									false, false)
+							.values());
+			Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
+			this.customizers = Collections.unmodifiableList(this.customizers);
+		}
+		return this.customizers;
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/context/embedded/ReactiveWebServerFactory.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+import java.util.Map;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.http.server.reactive.HttpHandler;
+
+/**
+ * Factory interface that can be used to create reactive {@link EmbeddedWebServer}s.
+ *
+ * @author Brian Clozel
+ * @since 2.0.0
+ * @see EmbeddedWebServer
+ */
+public interface ReactiveWebServerFactory {
+
+	/**
+	 * Gets a new fully configured but paused {@link EmbeddedWebServer} instance.
+	 * Clients should not be able to connect to the returned server until
+	 * {@link EmbeddedWebServer#start()} is called (which happens when the
+	 * {@link ApplicationContext} has been fully refreshed).
+	 * @param httpHandler the HTTP handler in charge of processing requests
+	 * @return a fully configured and started {@link EmbeddedWebServer}
+	 * @see EmbeddedWebServer#stop()
+	 */
+	EmbeddedWebServer getReactiveHttpServer(HttpHandler httpHandler);
+
+	/**
+	 * Register a map of {@link HttpHandler}s, each to a specific context path.
+	 *
+	 * @param handlerMap a map of context paths and the associated {@code HttpHandler}
+	 * @return a fully configured and started {@link EmbeddedWebServer}
+	 * @see EmbeddedWebServer#stop()
+	 */
+	EmbeddedWebServer getReactiveHttpServer(Map<String, HttpHandler> handlerMap);
+}

spring-boot/src/test/java/org/springframework/boot/context/embedded/AbstractReactiveWebServerFactoryTests.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2012-2017 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 org.springframework.boot.context.embedded;
+
+import org.junit.After;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.rules.TemporaryFolder;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import org.springframework.boot.testutil.InternalOutputCapture;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.server.reactive.HttpHandler;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.http.server.reactive.ServerHttpResponse;
+import org.springframework.util.SocketUtils;
+import org.springframework.web.reactive.function.BodyInserters;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.WebClient;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Base for testing classes that extends {@link AbstractReactiveWebServerFactory}.
+ *
+ * @author Brian Clozel
+ */
+public abstract class AbstractReactiveWebServerFactoryTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Rule
+	public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+	@Rule
+	public InternalOutputCapture output = new InternalOutputCapture();
+
+	protected EmbeddedWebServer webServer;
+
+
+	@After
+	public void tearDown() {
+		if (this.webServer != null) {
+			try {
+				this.webServer.stop();
+			}
+			catch (Exception ex) {
+				// Ignore
+			}
+		}
+	}
+
+	protected abstract AbstractReactiveWebServerFactory getFactory();
+
+	@Test
+	public void startStopServer() {
+		this.webServer = getFactory().getReactiveHttpServer(new EchoHandler());
+		this.webServer.start();
+		Mono<String> result = getWebClient()
+				.post().uri("/test")
+				.contentType(MediaType.TEXT_PLAIN)
+				.exchange(BodyInserters.fromObject("Hello World"))
+				.then(response -> response.bodyToMono(String.class));
+		assertThat(result.block()).isEqualTo("Hello World");
+
+		this.webServer.stop();
+		Mono<ClientResponse> response = getWebClient()
+				.post().uri("/test")
+				.contentType(MediaType.TEXT_PLAIN)
+				.exchange(BodyInserters.fromObject("Hello World"));
+		StepVerifier.create(response)
+				.expectError()
+				.verify();
+	}
+
+	@Test
+	public void specificPort() throws Exception {
+		AbstractReactiveWebServerFactory factory = getFactory();
+		int specificPort = SocketUtils.findAvailableTcpPort(41000);
+		factory.setPort(specificPort);
+		this.webServer = factory.getReactiveHttpServer(new EchoHandler());
+		this.webServer.start();
+
+		Mono<String> result = WebClient.create("http://localhost:" + specificPort)
+				.post().uri("/test")
+				.contentType(MediaType.TEXT_PLAIN)
+				.exchange(BodyInserters.fromObject("Hello World"))
+				.then(response -> response.bodyToMono(String.class));
+
+		assertThat(result.block()).isEqualTo("Hello World");
+		assertThat(this.webServer.getPort()).isEqualTo(specificPort);
+	}
+
+	protected WebClient getWebClient() {
+		return WebClient.create("http://localhost:" + this.webServer.getPort());
+	}
+
+	protected static class EchoHandler implements HttpHandler {
+		@Override
+		public Mono<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
+			response.setStatusCode(HttpStatus.OK);
+			return response.writeWith(request.getBody());
+		}
+	}
+}