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Web Development Interview Handbook

HTTP: Request Messages

Explore the structure and components of HTTP request messages in this lesson. Understand key HTTP methods such as GET, POST, PUT, DELETE, and how headers like Host, User-Agent, and Accept-language influence web requests. This lesson helps you grasp essential concepts for web communication and API interactions.

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Introduction

There are two types of HTTP messages, as discussed previously:

  • HTTP request messages
  • HTTP response messages

We’ll study request messages in this lesson.

HTTP request messages

Let’s look at request messages first. Here is an example of a typical HTTP request message:

Javascript (babel-node)
GET /path/to/file/index.html HTTP/1.1
Host: www.educative.io
Connection: close
User-agent: Mozilla/5.0
Accept-language: fr
Accept: text/html

It should be noted that:

  • HTTP messages are in plain ASCII text.
  • Each line of the message ends with two control characters: a carriage return and a line feed: \r\n.
    • The last line of the message also ends with a carriage return and a line feed!
  • This particular message has six lines, but HTTP messages can have one to as many lines as needed.
  • The first line is called the request line, while the rest are called header lines.

The anatomy of an HTTP request line

An HTTP request line is followed by an HTTP header. We’ll look at the request line first. The request line consists of three parts:

  • Method
  • URL
  • Version
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