EGEE Introduction to Webservices Course Practicle
-------------------------------------------------

This practical will show you how to write a client for a pre-defined
webservice, in this case the Barns and Noble book query service.

Step 0)
Create a directory for you to work in. Call it bnquote, and make it in
your user directory.

Step 1) WSDL

Get the WSDL from http://www.xmethods.com/
or, if that doesn't work there is a local copy here:
/opt/webservices_course/BNQuoteService.wsdl

Step 2) Generate the glue components

First, create a file called config.xml, and add the following lines to it:

<configuration xmlns="http://java.sun.com/xml/ns/jax-rpc/ri/config">
	<wsdl location="BNQuoteService.wsdl"
		packageName="bnquote" />
</configuration>

This is the configuration file for the wscompile utility that will generate
all of the glue code. The file tells wscompile which WSDL file to use, and
what package name we would like the glue code placed in.

Next, we run the wscompile utility itself:

wscompile -gen:client -keep -d . config.xml

This gets wscompile to generate the client code (-gen:client), keep the
generated source code so we can examine it later (-keep), work in the current
directory (-d .), using the configuration described in config.xml.

This will create a bnquote directory, which will contain a number of .class
and .java files that allow us to talk to the webservice.

Step 3) Write the client

Create a new file called bnclient.java in ~/bnquote/

First, we must import the various RPC libraries and glue code that we have
just generated:

// Standard libraries
import javax.xml.rpc.Service;
import javax.xml.rpc.Stub;

// Our glue code
import bnquote.BNQuoteService_Impl;
import bnquote.BNQuotePortType;

Next, we create our client class and give it two methods:

public class bnclient {

	public static float getPrice(String url, String isbn) throws Exception
	{

	}

	public static void main(String[] args)
	{

	}
}

Now, we'll write the getPrice function so that it calls a remote function
via webservices. Add the following to the getPrice function:

	BNQuoteService_Impl service = new BNQuoteService_Impl();
	BNQuotePortType port = service.getBNQuotePort();

The BNQuoteService_Impl class can be seen as the "class" of the webservice,
and BNQuotePortType can be seen as an "instance" of that class.
Now we call the remote "getPrice" method, as defined in our WSDL, and return
it to our caller:

	float value = port.getPrice(isbn);
	return (value);

And that is all that our getPrice client method needs. Now, we'll write some
code in our "main" method so that it calls our getPrice method:

	try{
		float price = getprice("http://services.xmethods.net:80/soap/servlet/rpcrouter", "0596003994");
		System.out.println(price);
	}
	catch (Exception e) {e.printStackTrace();}

That should now be all of the code that is required. Compile the code with:

javac bnclient.java


Step 4) Run the Client

Try the client out with:

java bnclient

If the client seems to hang, it could be because the remote service is down
 (welcome to the world of webservices! ;-)