RPC (Remote Procedure Call)

RPC- Remote Procedure Call
 The term itself defines calling remote methods through client program.
In this post added both server and client in the same package.
Normally we have to write server classes which having business functionality
and client will only will access that methods.

Step 1: Start Eclipse
Step 2: Create new dynamic project(name it as you like Ex: rpc-test
Step 3: Create a server class(Ex:Calculator)under src folder
Step 4: Write methods as of your requirement

Ex:

package com.siva;

public class Calculator 
{
public int add(int i1, int i2) {
return i1 + i2;
}
public int substract(int i1, int i2) {
return i1 - i2;
}
public int multiply(int i1, int i2) {
return i1 * i2;
}
}

Step 5: We have to write configuration of xmlrpcservlet in web.xml
Step 6: Open web.xml, which is under WEB-INF/

XmlRpcServlet
org.apache.xmlrpc.webserver.XmlRpcServlet

enabledForExtensionstrue
Sets, whether the servlet supports vendor extensions for XML-RPC.




XmlRpcServlet
xmlrpc

Step 7: Need to declare server class location in the properties file name called-
XmlRpcServlet.properties under package - org.apache.xmlrpc.webserver
Step 8: XmlRpcServlet.properties file details as mentioned below

Calculator=com.siva.Calculator

The bold Calculator is being used in clent class to access the Calculator methods.

Step 9: Write the Client class

package com.siva;

import java.net.URL;
import org.apache.xmlrpc.client.XmlRpcClient;
import org.apache.xmlrpc.client.XmlRpcClientConfigImpl;

public class SimpleClient {

public SimpleClient() {

try {
System.out.println("Try to call calculator methods via XML-RPC...");
XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();

//server ip addess or machine name/project name/servlet url pattern
config.setServerURL(new URL("http://127.0.0.1:8080/rpc-test/xmlrpc"));

XmlRpcClient client = new XmlRpcClient();
client.setConfig(config);

Object[] params = new Object[] { new Integer(2), new Integer(3) };
Integer result = (Integer) client.execute("Calculator.substract", params);

System.out.println("The returned values is: " + result);

} catch (Exception e) {
e.printStackTrace();
}
}

public static void main(String[] args) {
new SimpleClient();
}

}

in the above client class to call the RPC methods, first we have to provide the server ip addrss, url pattern name
While calling the method name which being used for to access the business logic.

Step 10: required jars

commons-logging-1.1.jar
ws-commons-util-1.0.2.jar
xmlrpc-client-3.1.3.jar
xmlrpc-common-3.1.3.jar
xmlrpc-server-3.1.3.jar
Step 11 : Required Tomcat server or any webserver to run the application

Step 12 : Start the server after adding project to the server and run the client application,
Run As Java Application, you will see the result.
If you want to call another methods , change the method name from Clicent class and stop start the
server.

I hope this post will help to get basic knowledge about RPC.