Spring Tutorials

Exposing services using RMI

Using Spring’s support for RMI, you can transparently expose your services through the RMI infrastructure. After having this set up, you basically have a configuration similar to remote EJBs, except for the fact that there is no standard support for security context propagation or remote transaction propagation.

Spring provides an easy way to run RMI application by the help of following classes:

1. org.springframework.remoting.rmi.RmiProxyFactoryBean
2. org.springframework.remoting.rmi.RmiServiceExporter classes.

RmiServiceExporter: This is the exportation service for the rmi object. This service can be accessed via plain RMI or RmiProxyFactoryBean.

RmiProxyFactoryBean: This is the factory bean for Rmi Proxies. It exposes the proxied service that can be used as a bean reference.

1. Spring 3.0
2. Eclipse IDE
3. Tomcat Server

There are some following step to make an Application using RMI with Spring as , The following example show how to write a simple Java SpringRMI application using RMI. To start with it, let us have working Eclipse IDE in place and follow the following steps to developed a Java Application:

Step1: Create a Java Project with a name SpringRMIntegration and create a package com.r4r under the src folder in the created project.

Step2: Create a interface Square.java under the com.r4r package that containing one sq(square) metod.

package com.r4r;
public interface Square {
	int sq(int number);
}

Step3: Create a Java Class SquareIml.java .This class provides the implementation of Square interface.

package com.r4r;
public class SquareImpl implements Square {
	@Override
	public int sq(int number) {
	return number*number;
}

Step4: Following are the list of JAR files required for this application, build configuration path and add the External Jars as given below.

1. Spring Core jar files
2. Spring Remoting jar files
3. Spring AOP jar files

Step5: Create a xml file applicationContext.xml. In this xml file we define the bean for SquareImpl class and RmiServiceExporter class.We need to provide values for the following properties of RmiServiceExporter class.

1. service
2. serviceInterface
3. serviceName
4. replaceExistingBinding
5. registryPort

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">

<bean id="squareBean" class="com.r4r.SquareImpl"></bean>
<bean class="org.springframework.remoting.rmi.RmiServiceExporter">

<property name="service" ref="squareBean"></property>
<property name="serviceInterface" value="com.r4r.Square"></property>
<property name="serviceName" value="SquareService"></property>
<property name="replaceExistingBinding" value="true"></property>
<property name="registryPort" value="1080"></property>
</bean>

</beans>

Step6: Create another xml file client-beans.xml. In this xml file, we define bean for RmiProxyFactoryBean. now we need to define two properties of this class.

1. serviceUrl
2. serviceInterface

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">

<bean id="squareBean" 
class="org.springframework.remoting.rmi.RmiProxyFactoryBean">
<property name="serviceUrl" 
value="rmi://localhost:1080/SquareService"></property>
<property name="serviceInterface" value="com.r4r.Square"></property>
</bean>

</beans>

Step7: Create a Java Class RMI.java.It is simply getting the instance of ApplicationContext.

package com.r4r;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class RMI{
public static void main(String[] args){
ApplicationContext context = 
new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println("Waiting for requests from client");
} }

Step8: Create a Java Class Client.java.It is simply getting the instance of Square and call the method.

package com.r4r;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Client {
public static void main(String[] args) {
ApplicationContext context =
new ClassPathXmlApplicationContext("client-beans.xml");
Square square = (Square)context.getBean("squareBean");
System.out.println(square.sq(10));
} }

Step9: Run this Application. First Run the RMI.java

Now Run Client.java.