What is a web service

Web services make software functionality available over the Internet so that programs like PHP, ASP, JSP, JavaBeans, the COM object, and all our other favorite widgets can make a request to a program running on another server (a web service) and use that program’s response in a website, WAP service, or other application.

So when I need to get some programming task done, and am too busy (or not crazy enough) to attempt it myself, I can make use of a web service by calling it over the Internet. By passing parameter data with the request, I can expect to receive a response containing the result generated by the web service.

Anyone who has used Hotmail recently has had a brush with web services: the passport authentication system is one of the web services in Microsoft’s .NET initiative, and is available without charge for the moment, so developers can use passport authentication within their own sites.

The principles behind web services are stunningly simple, and are nothing new in the world of distributed computing and the Internet:

the web service provider defines a format for requests for its service and the response the service will generate
a computer makes a request for the web services across the network
the web service performs some action, and sends the response back
This action might be retrieving a stock quote, finding the best price for a particular product on the net, saving a new meeting to a calendar, translating a passage of text to another language, or validating a credit card number.