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Spring Integration: A Lightweight Integration Approach

09.20.2013
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Today’s application expects access of all business in enterprise environment regardless of application technologies, which require, seamless integration with desperate systems.
This integration can be achieved through wiring of desperate systems using Middleware technologies.

Integration platform enables environment for applications to share information with each other to make architecture high interoperable.

Spring Integration provides a mediation framework to build lightweight integration solution using routing and mediation, regardless of protocols. The Spring Integration is lightweight routing and mediation framework and doesn’t need heavy weight ESB container to deploy.
Spring Integration uses Message object to communicate, route and pass the data, which is nothing, but a wrapper on Java object consists of payload and header. Payload consist data which could be any type such as File, String, stream etc. and header consist generic information on message such as id, timestamp etc.

Message communicates to producer via channel, which decoupled source from destination and post the message to any protocols such as JMS, HTTP, Ldap, file etc.
Producers send Messages to a channel, and consumers receive Messages from a channel

Spring Integration_Simple
Simple Integration Application

Below example show how producer send an employee object to channel and publisher receive message from channel.
Download Source code: Download the full code download link.

Spring Dependency Maven configuration

For starting simple integration example we just need to add the core spring integration and spring context dependency to maven pom.xml. Moreover we also need Junit and spring test to enable unit testing

<properties>
<spring.framework.version>3.2.3.RELEASE</spring.framework.version>
<spring.integration.version>2.2.4.RELEASE</spring.integration.version>
<junit.version>4.11</junit.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.framework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.integration</groupId>
<artifactId>spring-integration-core</artifactId>
<version>${spring.integration.version}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.framework.version}</version>
<scope>test</scope>
</dependency>
</dependencies>

Spring Configuration

We have to configure channel and gateway in spring configuration to send and receive message

SpringIntegTest-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/integration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration-2.2.xsd">
<!--
sendRequest
receiveRequest
-->
<annotation-config/>
<context:component-scan base-package="org.springsample.integration"/>
<gateway id="request" service-interface="org.springsample.integration.SentRequest"/>
<channel id="sendRequest"/>
<outbound-channel-adapter channel="sendRequest" ref="receiveResponse" method="processMessage" />
</beans:beans>

Here we created request gateway to send the message to channel and outbound adapter to receive message from the sendRequest channel.
Gateway of Spring Integration is entry points to send messages, which specify using Java Interface. Spring Integration automatically define proxy implementation at runtime
Request and Receive
Below we create the SentRequest and ReceiveResponse class to send and receive message as follows
SentRequest.java

package org.springsample.integration;
import org.springframework.integration.annotation.Gateway;
public interface SentRequest {
@Gateway(requestChannel="sendRequest")
public void process(Employee emp);
}

@Gateway annotation will indicate entry point to send message

package org.springsample.integration;
import org.springframework.integration.Message;
import org.springframework.integration.annotation.MessageEndpoint;
@MessageEndpoint
public class ReceiveResponse {
public void processMessage(Message<Employee> message) {
Employee employee = message.getPayload();
System.out.println("Message Received \n Name :"+employee.getName()+"/n Phone : "+employee.getPhone()+"/n Address :"+employee.getAddress());
}
}

@MessageEndpoint will indicate that it will receive message from channel via adapter.
Not but not leas below is Employee POJO

package org.springsample.integration;
public class Employee {
private String name;
private String title;
private String address;
private String phone;
public Employee(String name, String phone, String address) {this.name=name;this.phone=phone; this.address=address;
//……..Getter amd Setter
}
}

Testing

We can test this using spring test framework as below

package org.springbyexample.integration;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class SpringIntegTest {
@Autowired
private SentRequest request = null;
@Test
public void testIntegration() {
Employee emp = new Employee("John", "12345678", "Sunny Street Mac RG1");
request.process(emp);
}
}

Make sure you keep spring config file name SpringIntegTest-context in org/springbyexample/integration and should be in your class path
While running SpringIntegTest, it will display console message as follows


Message Received
Name :John/n Phone : 12345678/n Address :Sunny Street Mac RG1

Download Source code: download link.

Summary

Spring Integration is open source simple integration that enhances loose coupling and make application integration easy and simpler. It will integrate, route and mediate the message across the channel and gateway in configurable way.
This article helps to understand about Spring Integration and will aid you to develop a simple integration application.

Resources

http://static.springsource.org/spring-integration/reference/html/overview.html

Published at DZone with permission of Nitin Kumar, author and DZone MVB. (source)

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