Web Services are individual units of programming logic that exist on a web server. They can be integrated into all sorts of applications. It can convert our application into a Web Application, which can publish its content (function or message) to the rest of the world.
Web Services are built on a foundation of open standards. These standards allow web services to be created with .NET but consumed on other platforms or vice versa.
The root standard for all the individual web service standards is XML. Because XML is text-based, web service invocations can pass over normal HTTP channels. So, web services are governed by cross platform standards as well as easier to use.
Application programmers tend to treat a web service as a set of methods that can be called over the internet. XML gurus treat web services as a way to exchange XML messages.
Web Service Client: An application that uses a web service is called a Web Service Client.
Message: The information exchanged between the client application and the web service is called a message. Messages include the calls made by a client application to a Web Method and the data returned by the Web Method to the client.
When should Web Services be used?
Web Services should be used when our application needs to cross platform boundaries. Web Services are a perfect choice if we need to provide data to a Java Client running on a UNIX computer.
Web Services should also be used when our application needs to cross trust boundaries, which is crossed when our system incorporates applications from more than one company or organization. Web Services work well if we need to provide some information from a database to an application written by other developers.
When should Web Services not be used?
Web Services should not be used if we aren’t crossing platform or trust boundaries. Web Services are generally a poor way to share functionality between different types of applications in the same company.