Web Service Using Apache XML-RPC: Server And Client-Side

This article demonstrates how to use Apache XML-RPC in Java command-line applications. We will create programs both for the XML-RPC server and client. NOTE: This post is old and may not work with JDK 9 and beyond.

Software Environment

Windows 7 Professional SP1
Eclipse – Kepler Release
Java 1.7 (1.7.0_67 – Windows x86)
Apache Commons Codec 1.7
- Download from http://archive.apache.org/dist/commons/codec/. Choose file name with *current* substring.
- Used by the XML-RPC client
Apache Commons HttpClient 3.0
- Download from http://archive.apache.org/dist/httpcomponents/commons-httpclient/3.0/binary/
- Used by the XML-RPC client
Apache XML-RPC 3.1.3
- Download from https://archive.apache.org/dist/ws/xmlrpc/binaries/
Apache Tomcat 7.0.56
- We’ll reference and use only the servlet-api.jar file from Tomcat.
- Used by the XML-RPC server only

Create an XML-RPC Project in Eclipse

XML-RPC is the precursor of SOAP. Before writing the codes, you need to create a Java project in Eclipse. Then, download the files and manually put them in a folder (in this case, the “lib” folder) within the project. Lastly, reference all these jar files.

The Apache XML-RPC Web Service: Server-Side

When creating a server, we need three (3) things:

Our service class.
It is a POJO whose methods can be invoked by remote clients, of course, via XML-RPC and through the XML-RPC server.
XmlRpcServlet.properties
This is where we register our service class so that the XML-RPC server can route RPC calls to the appropriate object and method. If we have worked on Servlets, the file is like our web.xml for this command-line application.IMPORTANT: This file needs to be in org.apache.xmlrpc. Webserver package. Create this package in our project and move or save the .properties file there.
A reference to servlet-api.jar
The ServletWebServer class uses this.

The XML-RPC server codes are written as follows:

import org.apache.xmlrpc.webserver.ServletWebServer;
import org.apache.xmlrpc.webserver.XmlRpcServlet;

public class XmlRpcServer {
    public static void main(String[] args) throws Exception {
        XmlRpcServlet servlet = new XmlRpcServlet();
        ServletWebServer webServer = new ServletWebServer(servlet, 1000);
        webServer.start();
        System.out.println("XML-RPC Server running...");
    }
}

import org.apache.xmlrpc.webserver.ServletWebServer;

import org.apache.xmlrpc.webserver.XmlRpcServlet;

public class XmlRpcServer {

public static void main(String[] args) throws Exception {

XmlRpcServlet servlet = new XmlRpcServlet();

ServletWebServer webServer = new ServletWebServer(servlet, 1000);

webServer.start();

System.out.println("XML-RPC Server running...");

}

Modify XmlRpcServlet.properties

Next, register our service class on this file. Note that we need a fully qualified name of the class. In this article, my CalculartorWebService class resides in the default package.

Calculator=CalculatorWebService

1	Calculator=CalculatorWebService

The Apache XML-RPC Web Service Client

We can run both the server and client applications in Eclipse.

package org.apache.xmlrpc.webserver;
import java.net.URL;

import org.apache.xmlrpc.client.XmlRpcClient;
import org.apache.xmlrpc.client.XmlRpcClientConfigImpl;
import org.apache.xmlrpc.client.XmlRpcCommonsTransportFactory;

public class MyXmlRpcClient {
    public static void main(String[] args) throws Exception {
        XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();
        config.setServerURL(new URL("http://localhost:1000"));
        XmlRpcClient client = new XmlRpcClient();
        client.setTransportFactory(new XmlRpcCommonsTransportFactory(client));
        client.setConfig(config);
        Object[] params = new Object[]{new Integer(2), new Integer(3)};
        Integer result = (Integer) client.e xecute("Calculator.add", params);
        System.out.println(result);
    }   
}