INT-3991: Add IntegrationGraphController

JIRA: https://jira.spring.io/browse/INT-3991

* Add `IntegrationGraphController` `@RestController` over `IntegrationGraphServer` bean
* Add `@EnableIntegrationGraphController` and `<int-http:graph-controller>` to register
`IntegrationGraphController` if the `DispatcherServlet` is in classpath.
* Also register the `IntegrationGraphServer` bean from the same place, if that isn't presented in the application context yet.
* Allow to configure the "root" `path` for the `IntegrationGraphController` as a placeholder value via
`spring.integration.graph.controller.request.mapping.path` property
* Add tests for both `@EnableIntegrationGraphController` and `<int-http:graph-controller>` cases based on the `MockMvc`

spring-integration-http/src/test/java/org/springframework/integration/http/management/IntegrationGraphControllerParserTests-context.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans
+		xmlns="http://www.springframework.org/schema/integration/http"
+		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		xmlns:beans="http://www.springframework.org/schema/beans"
+		xmlns:mvc="http://www.springframework.org/schema/mvc"
+		xsi:schemaLocation="http://www.springframework.org/schema/integration/http
+		http://www.springframework.org/schema/integration/http/spring-integration-http.xsd
+		http://www.springframework.org/schema/beans
+		http://www.springframework.org/schema/beans/spring-beans.xsd
+		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
+
+	<mvc:annotation-driven/>
+
+	<graph-controller path="/foo"/>
+
+</beans:beans>

spring-integration-http/src/test/java/org/springframework/integration/http/management/IntegrationGraphControllerTests.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2016 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.integration.http.management;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.handler;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.hamcrest.Matchers;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.http.config.EnableIntegrationGraphController;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.servlet.HandlerAdapter;
+import org.springframework.web.servlet.HandlerExecutionChain;
+import org.springframework.web.servlet.HandlerMapping;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
+
+/**
+ * @author Artem Bilan
+ * @since 4.3
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration
+@WebAppConfiguration
+public class IntegrationGraphControllerTests {
+
+	@Autowired
+	private WebApplicationContext wac;
+
+	private MockMvc mockMvc;
+
+	@Before
+	public void setup() {
+		this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
+	}
+
+	@Test
+	public void testIntegrationGraphGet() throws Exception {
+		this.mockMvc.perform(get("/testIntegration")
+				.accept(MediaType.parseMediaType("application/json;charset=UTF-8")))
+				.andExpect(status().isOk())
+				.andExpect(content().contentType("application/json;charset=UTF-8"))
+				.andExpect(handler().handlerType(IntegrationGraphController.class))
+				.andExpect(handler().methodName("getGraph"))
+				.andExpect(jsonPath("$.nodes..name")
+						.value(Matchers.containsInAnyOrder("nullChannel", "errorChannel",
+								"_org.springframework.integration.errorLogger")))
+				.andExpect(jsonPath("$.links").exists());
+	}
+
+	@Test
+	public void testIntegrationGraphControllerParser() throws Exception {
+		ConfigurableApplicationContext context = new ClassPathXmlApplicationContext(
+				"IntegrationGraphControllerParserTests-context.xml", getClass());
+
+
+
+		HandlerMapping handlerMapping =
+				context.getBean(RequestMappingHandlerMapping.class.getName(), HandlerMapping.class);
+
+		HandlerAdapter handlerAdapter = context.getBean(RequestMappingHandlerAdapter.class);
+
+		MockHttpServletRequest request = new MockHttpServletRequest();
+		request.setMethod("GET");
+		request.setRequestURI("/foo");
+		MockHttpServletResponse response = new MockHttpServletResponse();
+
+		HandlerExecutionChain executionChain = handlerMapping.getHandler(request);
+		assertNotNull(executionChain);
+
+		Object handler = executionChain.getHandler();
+
+		handlerAdapter.handle(request, response, handler);
+		assertEquals(HttpStatus.OK.value(), response.getStatus());
+		assertThat(response.getContentAsString(), containsString("\"name\":\"nullChannel\","));
+		assertThat(response.getContentAsString(), not(containsString("\"name\":\"myChannel\",")));
+
+		context.getBeanFactory().registerSingleton("myChannel", new DirectChannel());
+
+		request = new MockHttpServletRequest();
+		request.setMethod("GET");
+		request.setRequestURI("/foo/refresh");
+		response = new MockHttpServletResponse();
+
+		executionChain = handlerMapping.getHandler(request);
+		assertNotNull(executionChain);
+
+		handler = executionChain.getHandler();
+
+		handlerAdapter.handle(request, response, handler);
+		assertEquals(HttpStatus.OK.value(), response.getStatus());
+		assertThat(response.getContentAsString(), containsString("\"name\":\"myChannel\","));
+
+		context.close();
+	}
+
+	@Configuration
+	@EnableWebMvc
+	@EnableIntegration
+	@EnableIntegrationGraphController(path = "/testIntegration")
+	public static class ContextConfiguration {
+
+	}
+
+}

spring-integration-http/src/test/resources/log4j.properties

@@ -0,0 +1,9 @@
+log4j.rootCategory=WARN, stdout
+
+log4j.appender.stdout=org.apache.log4j.ConsoleAppender
+log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
+log4j.appender.stdout.layout.ConversionPattern=%d{HH:mm:ss.SSS} %-5p [%t][%c] %m%n
+
+#log4j.category.org.springframework=DEBUG
+log4j.category.org.springframework.integration=WARN
+log4j.category.org.springframework.integration.http=WARN