8. Using XML-RPC with Java

Hannes Wallnöfer has provided an excellent implementation of XML-RPC for Java.

To install it, download the distribution, unzip it, and add the *.jar files to your CLASSPATH. On a Unix system, you can do this by typing:

bash$ unzip xmlrpc-java.zip
bash$ cd xmlrpc-java/lib
bash$ CLASSPATH=`pwd`/openxml-1.2.jar:`pwd`/xmlrpc.jar:$CLASSPATH

8.1. A Java Client

Save the following program in a file named JavaClient.java.

import java.util.Vector;
import java.util.Hashtable;
import helma.xmlrpc.*;
public class JavaClient {
    // The location of our server.
    private final static String server_url =
        "http://xmlrpc-c.sourceforge.net/api/sample.php";
    public static void main (String [] args) {
        try {
            // Create an object to represent our server.
            XmlRpcClient server = new XmlRpcClient(server_url);
            // Build our parameter list.
            Vector params = new Vector();
            params.addElement(new Integer(5));
            params.addElement(new Integer(3));
            // Call the server, and get our result.
            Hashtable result =
                (Hashtable) server.execute("sample.sumAndDifference", params);
            int sum = ((Integer) result.get("sum")).intValue();
            int difference = ((Integer) result.get("difference")).intValue();
            // Print out our result.
            System.out.println("Sum: " + Integer.toString(sum) +
                               ", Difference: " +
                               Integer.toString(difference));
        } catch (XmlRpcException exception) {
            System.err.println("JavaClient: XML-RPC Fault #" +
                               Integer.toString(exception.code) + ": " +
                               exception.toString());
        } catch (Exception exception) {
            System.err.println("JavaClient: " + exception.toString());
        }
    }
}

8.2. A Stand-Alone Java Server

Save the following program in a file named JavaServer.java.

import java.util.Hashtable;
import helma.xmlrpc.*;
public class JavaServer {
    public JavaServer () {
        // Our handler is a regular Java object. It can have a
        // constructor and member variables in the ordinary fashion.
        // Public methods will be exposed to XML-RPC clients.
    }
    public Hashtable sumAndDifference (int x, int y) {
        Hashtable result = new Hashtable();
        result.put("sum", new Integer(x + y));
        result.put("difference", new Integer(x - y));
        return result;
    }
    public static void main (String [] args) {
        try {
            // Invoke me as <http://localhost:8080/RPC2>.
            WebServer server = new WebServer(8080);
            server.addHandler("sample", new JavaServer());
        } catch (Exception exception) {
            System.err.println("JavaServer: " + exception.toString());
        }
    }
}