Web Services At A Glance

A Web Service is a way or method of communication between two electronic devices over a network. 
Web services are Web applications that are based on open standard ( XML, SOAP, HTTP etc.) . And they interact with other web applications .

We can also say that a Web service  is a software function which is provided at a network address over the Web with the service always on as in the concept of utility computing.

 The W3C defines a Web service  as:-
"A software system designed to support interoperable machine-to-machine interaction over a network.[1]
A web service is any piece of software that makes itself available over the internet and uses a standardized XML messaging system."

Web services are built on top of open standards such as TCP/IP, HTTP, Java, HTML, and XML.
Web services are XML-based information exchange systems(programs) and they use the Internet for direct application-to-application interaction.

Rules for communication are defined in a file called WSDL (Web Services Description Language), which has the extension .wsdl.

Any web service has following characterstics:

  • It is available over the Internet or private (intranet) networks
  • It uses a standardized XML messaging system
  • Is not tied to any one operating system or programming language

There are two major classes of Web services:

  • REST-compliant Web services
  • Arbitrary Web services

  • REST-compliant Web services -  in which the primary purpose of the service is to manipulate XML representations of Web resources .
  • Arbitrary Web services expose an arbitrary set of operations.