Chapter 2

2.0. A second look at HTTP

We have seen that REST uses HTTP for data communication as browsers do. Virtually everything we will be doing with REST will be through HTTP. It is therefore important we take a closer look at HTTP itself.

HTTP is one of the protocols for data communication on the internet. It enables data transmission in a request-response pattern. The client sends a request for a resource to the server. The server in turn replies with a response. When you type a web address in a browser (client), that is basically what happens - the browser sends a request for the webpage and the server sends a response with the page’s content.

An HTTP message (request or response) has the format:

• An initial line
• Zero or more header lines
• A blank line, and
• An optional message body

Let’s look at both message types.