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.

struts example

Struts example

Below post shows how to build simple application with struts.

open eclipse -> project -> create dynamic Webproject->

provide name as - struts_sample [As you like]

select Dynamic web module version as 2.5

Then click on Finish button.

-> open the web.xml , which available inside WEB-INF folder

copy the below code and paste in side web.xml .

      
             action 
              org.apache.struts.action.ActionServlet     
               
                   config                   /WEB-INF/struts-config.xml              
              1
  
     
		       action   
		       *.do
    

-> Create xml and name it as struts-config.xml inside WEB-INF.
->open the struts-config.xml and paste the below code inside the struts-config.xml

-> Now it's time to start our work like creating jsp files, form classes, action classes and need to add required jars.

-> first we will write jsp page. Here i am writting 4 jsp pages
1. login.jsp
2. welcome.jsp
3. adduser.jsp
4. success.jsp

-> create one folder inside WebContent with name jsp [WebContent/jsp/login.jsp] -- this is for login details which will have user name and password along with validation.
paste the below code inside login.jsp

	<%@taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%><%@taglib
	uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean"%>







	
Login
	
		
	
	

-> create welcome.jsp [WebContent/jsp/welcome.jsp] -- this is for after successful login details .
paste the below code inside welcome.jsp

	
	<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
	pageEncoding="ISO-8859-1"%>






	<%        String message = (String)request.getAttribute("message");    %>
	
		Welcome User :
		<%= message %>
You have successfully logged in.

-> create adduser.jsp [WebContent/jsp/adduser.jsp] -- this contains user details along with required validation.
paste the below code inside adduser.jsp

	<%@taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%><%@taglib
	uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean"%>







	
	
		
	

-> create success.jsp [WebContent/jsp/success.jsp] -- this page will display after successful user details.
paste the below code inside success.jsp

	<%@taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%><%@taglib
	uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean"%>






	
success
	successfully Added.

-> We need to create java classes.
-> create a package -> com.siva.form
-> com.siva.action

->create LoginForm.java inside com.siva.form package and paste the below code.

package com.siva.form;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;

/**
 * 
 * @author sivaraju
 *
 */
public class LoginForm extends ActionForm {
	/**
	 * 
	 */
	private static final long serialVersionUID = -1743531020254647308L;
	private String userName;
	private String password;

	public ActionErrors validate(ActionMapping mapping,
			HttpServletRequest request) {
		ActionErrors actionErrors = new ActionErrors();
		if (userName == null || userName.trim().equals("")) {
			actionErrors.add("userName", new ActionMessage("error.username"));
		}
		try {
			if (password == null || password.trim().equals("")) {
				actionErrors.add("password",
						new ActionMessage("error.password"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return actionErrors;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
}

->create UserForm.java inside com.siva.form and paste below code

  package com.siva.form;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;

/**
 * 
 * @author sivaraju
 *
 */
public class UserForm extends ActionForm {
	/**
	 * 
	 */
	private static final long serialVersionUID = -2087861874662967982L;
	private String userName;
	private String sex;
	private int age;

	public ActionErrors validate(ActionMapping mapping,
			HttpServletRequest request) {
		ActionErrors actionErrors = new ActionErrors();
		try {
				if (userName == null || userName.trim().equals("")) {
					actionErrors.add("userName", new ActionMessage("error.username"));
				}
				if (sex == null || sex.trim().equals("")) {
					actionErrors.add("sex",new ActionMessage("error.sex"));
				}
				if (age <=0 ) {
					actionErrors.add("age",new ActionMessage("error.age"));
				}
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		return actionErrors;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	
}

-> create LoginAction.java inside com.siva.action pakage and paste the below code

  package com.siva.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import com.siva.form.LoginForm;

public class LoginAction extends Action {
	private static final String FAILURE = "failure";
	private static final String SUCCESS = "success";

	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		String target = null;
		LoginForm loginForm = (LoginForm) form;
		if (loginForm.getUserName().equals("admin")
				&& loginForm.getPassword().equals("admin123")) {
			target = SUCCESS;
			request.setAttribute("message", loginForm.getUserName());
		} else {
			target = FAILURE;
		}
		return mapping.findForward(target);
	}
}

-> create AddUserAction.java inside com.siva.action package and paste below code.

package com.siva.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import com.siva.form.UserForm;
/**
 * 
 * @author sivaraju
 *
 */
public class AddUserAction extends Action {
	private static final String SUCCESS = "success";

	/**
	 * 
	 */
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		UserForm userForm = (UserForm) form;
		System.out.println("username["+userForm.getUserName()+"]");
		System.out.println("Age["+userForm.getAge()+"]");
		System.out.println("Sex["+userForm.getSex()+"]");
		//If this details need to store in db. Then need to get the db details from data source object. Store as per requirement.
		return mapping.findForward(SUCCESS);
	}
	
	
}

->create MessageResource.properties file inside src/resource [src/resource/MessageResource.properties] and paste the below code

label.username = User Name
label.password = Password
label.welcome = Welcome 
error.username =Username is required.
error.password = Password is required.


label.age = Age
label.sex = Sex

label.adduser = Add User


error.age = Age is required field
error.sex=Sex is required field 

-> Add the below jars inside lib folder.(Among below jar's few of the jar's may not be required]

    bcprov-jdk14-121.jar
    commons-digester-2.1.jar
    commons-fileupload-1.1.1.jar
    commons-io-1.2.jar
    commons-lang-2.4.jar
    org-apache-commons-logging.jar
    org.apache.commons.beanutils.jar
    servlet-api.jar
    struts.jar
	
	

-> Right click on the project-> Run As-> Run On Server-> [select the server which ever server you want to run the application]. Tomcat is prefered. -> http://localhost:8080/struts_sample/login.jsp [ after submitting it will redirect to welcome.jsp]- username - admin / password - admin123 -> http://localhost:8080/struts_sample/jsp/adduser.jsp [after submitting it will redirec tto success.jsp]. In this way stuts application will work.