ASP.NET and Web Services

The ASP.NET framework simplifies development of web services. All the low-level work, such as packaging and unpackaging data in XML format and utilizing HTTP protocol to transport the web messages between distributed components, are done by the framework. This allows the developers to focus on the application logic.

The .NET Framework uses asmx as the default file extension for web services, as opposed to aspx for Web Forms and ascx for web controls.

The WebService Directive

All asmx files start with the @WebService directive that instructs ASP.NET on how to compile the code, as well as the main class name. The WebService directive has the following attributes:


Specifies the language in which the code was written. This instructs the ASP.NET framework to use the appropriate compiler to build your web service. Use vb for Visual Basic and c# for C#. As other languages emerge, obviously you can specify other languages.


Specifies the main class, which exposes web methods. The ASP.NET framework instantiates this class in order to serve the web methods to the clients.


Specifies the source file for your code, which allows for complete code/ASP separation.

You can easily create a simple web service similar to the following asmx file:

<%@ WebService Language="VB" Class="MyClass" %>
Public Class MyClass
  Public Function <WebMethod(  )> Add(a as integer, b as integer) as 
    Return a + b
  End function
End class

If you prefer to separate your ...

Get .Net Framework Essentials now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.