Invoking a public web service programmatically using WSO2 WSAS

A Web service is defined as "a software system designed to support interoperable interaction over a network." Web services are referred to as Web APIs that can be accessed over a network and executed on a remote system hosting the requested services.
There are many publicly available web services which can be invoked remotely using client applications. www.webservicex.net is such a site that hosts different types of public web services.
I'm going to demonstrate how such web service is invoked programmaticaly using WSO2 Web services application server (WSO2 WSAS)

WSo2 Web services application server provides set of tools to interact with web services. You can download the latest version from here.

I'll use a public instance of WSO2 WSAS to generate client side code (stub). You will also try out WSAS public instance before downloading the server.

Step 1

First, we may access webservicex to identify a suitable web service which can be invoked remotely.
You may see 'Top Web Services' at the left menu of the home page. Click on 'Stock Quote'
You will get a page with stock quote service details.

Make a note of the followings;
Endpoint http://www.webservicex.net/stockquote.asmx
WSDL Location http://www.webservicex.net/stockquote.asmx?wsdl

Step 2

WSO2 provides a set of shared instances of WSO2 Web services application server at http://wso2.org/tools. You can easily try out several features of web services application server with these instances.

Go to WSAS 2.2 shared instances page and select 'shared WSO2 WSAS Instance 1'. You will be directed to the home page of WSAS management console. Select WSDL2Code from the left navigation menu.
You will see the following page.



Enter 'http://www.webservicex.net/stockquote.asmx?wsdl' as the uri of WSDL. We need to generate a client to invoke the stock quote service. Therefore, you don't want to configure server side settings. Simply click on 'generate' leaving the other fields blank.

Within a few seconds, you will be prompted to save a zip file in your file system. Save it in your machine.

Step 3

Go to the directory where you saved the generated zip file. You will see src directory, pom.xml and build.xml file inside the zip file. src directory contains the StockQuoteStub and StockQuoteCallbackHandler classes which can be considered as proxies used in our client.

Now open a command window and go to the extracted directory where the above pom.xml exists.
Assuming you are using Eclipse as IDE, enter mvn eclipse:eclipse to generate the complete project structure which can be imported in to your IDE. (If Intellij IDEA is used, then use mvn idea:idea)

Depending on your network connection and the contents available in your maven2 repository, the above command takes some time to download the necessary jars to your m2 repo.

If everything is successful, you will see 'BUILD SUCCESSFUL' message.

Step 4

Open eclipse IDE. Select File-->Import.
Select 'Existing projects in to workspace'. In the 'Import Projects' window, browse for the root directory of the above location (where you extracted the generated zip file)
Select the project and click next

The complete project structure will be created with the generated artifacts. You may need to define M2_REPO classpath variable if you have not done it previously.

Step 5

Now use the generated stubs to create a java client under the above project to consume Stock Quote service.

public class StockQuoteClient {

public static void main(String[] args)throws AxisFault {
StockQuoteStub stub = new StockQuoteStub("http://www.webservicex.net/stockquote.asmx");
StockQuoteStub.GetQuote req = new StockQuoteStub.GetQuote();
req.setSymbol("IBM");
try {
StockQuoteStub.GetQuoteResponse response = stub.GetQuote(req);
System.out.println(response.getGetQuoteResult());
} catch (RemoteException e) {
e.printStackTrace();
}

}

}

Run the application. You will get the stock quote for IBM.