Webservice client using dynamic proxy

In one of my previous posts, i explained how to create a WebService and access it from a simple client. If you look at the client code which accesses the webservice, you will find that the client is using the stubs that were created at deploy time. Such clients which use "static stubs" for accessing webservices are known as "Static Stub Clients". In such approach, the clients will have to have the stubs in their classpath.

Another approach of accessing the webservices is through Dynamic Proxies where the proxies are generated at runtime. I will be showing a simple client which uses dynamic proxies to access an webservice. I wont be explaining the steps to deploy the webservice (which i have already done in my other post). This example assumes that the webservice is already deployed on the server.

The client code will be accessing the HelloWorld service and invoking the sayHelloTo method on that service (Refer my other post to see how the service has been deployed onto the server)

Here's the code for the client:

package org.myapp.service.client;

import java.net.MalformedURLException;
import java.net.URL;

import javax.xml.namespace.QName;
import javax.xml.rpc.Service;
import javax.xml.rpc.ServiceException;
import javax.xml.rpc.ServiceFactory;

import org.myapp.service.HelloWorldService;

/**
 * Simple webservice client which uses dynamic proxy
 *
 * @author Jaikiran Pai
 */
public class DynamicProxyClient {

    public static void main(String args[]) {

        try {
            
            // ServiceFactory instance
            ServiceFactory serviceFactory = ServiceFactory.newInstance();
            System.out.println("Got the service factory");
            String wsdlURLString = "http://localhost:8080/axis/services/HelloWorld?wsdl";
            URL wsdlURL = new URL(wsdlURLString);
            String serviceName = "HelloWorldServiceService";
            String nameSpaceURI = "http://jaikiran.com";
            String portName = "HelloWorld";
            // get hold of the service by passing the URL of the wsdl and the
            // service name
            Service service = serviceFactory.createService(wsdlURL, new QName(
                    nameSpaceURI, serviceName));
            System.out.println("Got the service: " + service);
            // create the service proxy
            HelloWorldService serviceProxy = (HelloWorldService) service
                    .getPort(new QName(nameSpaceURI, portName),
                            HelloWorldService.class);
            System.out.println("Got the service proxy: " + serviceProxy);
            System.out.println("Invoking method on service proxy........");
            System.out.println(serviceProxy.sayHelloTo("Dynamic user"));

        } catch (ServiceException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

1) Our first step would be to create a ServiceFactory instance, using which we can get access to a deployed service.

ServiceFactory serviceFactory = ServiceFactory.newInstance();

2) Once the ServiceFactory has been created, we will be getting hold of the service which is deployed on the server. To do this, we require
a) The url of the wsdl of the deployed service. In this example it will be http://localhost:8080/axis/services/HelloWorld?wsdl

b) The namespace uri. In this example it will be http://jaikiran.com (You can get this uri from the wsdl file)

c) The name of the service which you want to access. In this example it will be HelloWorldServiceService

String wsdlURLString = "http://localhost:8080/axis/services/HelloWorld?wsdl";
URL wsdlURL = new URL(wsdlURLString);
String serviceName = "HelloWorldServiceService";
String nameSpaceURI = "http://jaikiran.com";

// get hold of the service by passing the URL of the wsdl and the
// service name
Service service = serviceFactory.createService(wsdlURL, new QName(
                    nameSpaceURI, serviceName));
                    

3) At this point you have got access to the service. But in order to invoke an method on the service, you will have to create a proxy (dynamic proxy) from this service. The Service class, has an API getPort, which creates the proxy. In order to create the proxy, we will have to pass the portName of the service (again, this can be obtained in the wsdl file), the namespace uri and the class type of the service. In this example the service interface is org.myapp.service.HelloWorldService, so we will be passing this as the class as follows:

String portName = "HelloWorld";
// create the service proxy
HelloWorldService serviceProxy = (HelloWorldService) service
                    .getPort(new QName(nameSpaceURI, portName),
                     org.myapp.service.HelloWorldService.class);

4) At this point we have got the service proxy which is of type org.myapp.service.HelloWorldService. We can now invoke our sayHelloTo method on this proxy:

System.out.println(serviceProxy.sayHelloTo("Dynamic user"));

Simple, isnt it? You have successfully invoked the webservice through a standalone client using dynamic proxy.