Introduction to Building XML Web Services with ASMX
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The Web Service standards define how to build application functionality that is made available to remote machines using generally available Internet protocols. The Web part defines how application functionality is accessed. The services relate to the idea of providing reusable application functionality without having to download or install application code. Using Web Services, Service Oriented Applications (SOA) capitalize on this set of principles as the way to build and deploy a set of distributed services. Any interaction with the set of services is governed by a set of exposed schema, contract and policies. SOA then extends these basic concepts to define services as autonomous, independently deployed and a version managed entity within an application.
The end result is that Web Services become the general framework for building service endpoints that communicate over HTTP. This enables a design pattern that allows companies to move from the traditional tightly coupled applications to a loosely coupled service oriented model. In this new paradigm larger systems are composed of smaller ones that provide the building blocks to dynamically assemble and deliver cooperative enterprise services. Fundamentally, architecture designed this way allows any application including mobile applications to easily assemble and leverage back end services from existing components.
Like SOA, Web Services are an abstract concept based on a growing set of industry driven standards. One of the ways the .NET Framework implements theses is the System.Web.Services namespace within a Web Service end point (.asmx page) that is executed by the ASP.NET runtime. Another way is to use the Windows Communication Foundation (WCF) within the .NET Framework 3.0. In this article we will explore how these integrated concepts are used to build ASMX Web Services with Visual Studio 2005 and the .NET Framework.