Accessing Web Sources - Beginning Java Programming: The Object-Oriented Approach - page 373

<soap:Envelope xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd=" http://www.w3.org/2001/XMLSchema"
xmlns:soap=" http://schemas.xmlsoap.org/soap/envelope/" >
<soap:Body>
<GetQuoteResponse xmlns=" http://www.webserviceX.NET/">
<GetQuoteResult>string</GetQuoteResult>
</GetQuoteResponse>
</soap:Body>
</soap:Envelope>

So now you know you can expect a SOAP reply message with a GetQuoteResponse tag con-
taining one internal tag— GetQuoteResult— which you can parse in your program.

7.

Finally, note that the web service also provides a WSDL file, which you will see later on in a bit
more depth.

How It Works

Here's how it works:
1.

The http://www.webservicex.net website hosts a number of useful SOAP services, one of which
is the stock quote provider.

2.

Each SOAP service provides a number of “operations.” Think of these as “methods” you can call
on the service. In the case of the stock quote provider, only one operation is provided: GetQuote .

3. SOAP requests can be sent to invoke a service operation. To do so, a request message needs to

be constructed that will be sent to the service URI (the endpoint). That method must contain a
SOAPAction header with the operation you want to call and a message body containing the param-
eters you want to send to the operation handler. The WebserviceX.NET websites provides example
messages for each of its operations.

4.

If the request succeeds, you know you will receive a reply formatted to the specifications as shown
on the example page. You know you can expect a SOAP reply message with a GetQuoteResponse
tag containing one internal tag: GetQuoteResult . This tag contains a “string”—you can't be sure
yet how this string is formatted or what information it contains, so you'll need to take a closer look
at it once you receive SOAP replies in your program.

It's time to get started and see how you can access this service in Java. Create a class called
ClientWithoutWSDL to do so. From the example in the Try It Out, you know that you will need the
following to access the web service:

➤

The hostname of the service. In this case, this is www.webservicex.net .

➤

The “endpoint” to which you should send the request using HTTP. For the “Stock Quote”
web service, this is /stockquote.asmx . Together with the hostname, this forms the full end-
point URI: http://www.webservicex.net/stockquote.asmx .

➤

The name of the operation you want to invoke. In this case, this is GetQuote . The name of
the operation is also used to construct the SOAPAction header: http://www.webserviceX
.NET/GetQuote .