Chapter 1. Introduction to REST

When we look around the Web today, we can see a whole new breed of web applications compared to those available a few years back. It is a whole new Web, and some even call it as Web 2.0. What makes Web 2.0 possible? Web services are one of the key technologies that make the Web as powerful as we can see it is today.

Web services allow heterogeneous systems to communicate with each other using messages. Because the systems could be heterogeneous, the need for interoperability arises. Hence XML is often used to format the messages. Because XML is in text format, almost all systems can understand the messages and work with each other. Messages are used when it comes to communicating between applications that run on different machines. As an example, in a chat application, the text typed in by the users are wrapped in messages, along with the data that would explain where the message should go and how that should be interpreted and passed between the server applications.