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The exodus from Visual Studio 6.0 to .NET has begun for most
developers. But with this new coding model comes decoupled services in the form
of Web services.

However, if you still have to maintain and develop using
standard ASP, you’ll have to develop systems that interact with .NET Web
services. With the Microsoft SOAP Toolkit 3.0, this interaction is simple to
implement.

Creating an ASP.NET Web service

It’s simple to create an ASP.NET Web service within the
Visual Studio .NET IDE. If you don’t have Visual Studio .NET, you can also use
the free ASP.NET Web Matrix IDE available at the ASP.NET
site.

Create an ASP.NET Web service project called Hello. This will also become your
project’s namespace. Within this project, add a Web service called HelloWorldService.
At this point, the IDE usually adds a sample method called HelloWorld, which returns the
string “Hello World”.

After you complete these tasks, your code should look
similar to Listing A.

Test your code by navigating to your Web service page. Invoke the HelloWorld method of your Web
service. If you get the “Hello World” string return value, you can
proceed to the next step: creating an ASP.NET Web service consumer.

Consuming an ASP.NET Web service

The Microsoft
SOAP Toolkit 3.0 provides the mechanisms for consuming a SOAP Web service.
The MSSOAP.SoapClient object consumes the Web service
functionality in an object-oriented style.

When you initialize the client using the WSDL for the Web
service and the service name, the SoapClient object
absorbs the available service methods. For example, your Web service has a
method called HelloWorld.
When you initialize the SoapClient object, the HelloWorld
service method is now a method of the SoapClient
object. You can see this in Listing B.

You initialize the SoapClient
object with the mssoapinit
method, which takes two parameters: the path to the WSDL file and the name of
the Web service. One of the benefits of ASP.NET Web services is that you simply
point to the .asmx file of your Web service appended
with “?WSDL”. This returns the WSDL of the service.
And, to use the service method HelloWorld, you need to call the HelloWorld method of the SoapClient object. This simple ASP page will prepare an
HTML page with the text “Hello World”.

Cost of creating and consuming an ASP.NET Web service

It’s essentially free to consume ASP.NET Web services when
you use the free .NET Framework download, the free Microsoft SOAP Toolkit
download, and the free ASP.NET Web Matrix. You can build standard ASP pages
using a simple text editor. The only thing that you would need to pay for is
the operating system that supports IIS 5.0 or above. This is available in
Microsoft Windows 2000, Microsoft Windows XP Professional, or Microsoft Windows
2003.

Now you should be able to expand upon my simple examples and
create your own .NET Web service consumers using standard ASP.