HTTP - Request

About

An HTTP request is a message sent from a client to a server.

It's the first part of a fetch, the second being the response.

Structure

A request message has:

a first line called the request line that includes:
- the method that the server should execute for the client.
- the request URI which may have one of the the following values:
  - the URI that defines where the request should be send.
  - the absolute path. The host is then used to recreate the URI
  - or * for a options request.
- and the http version
headers
and an optional body

method url httpVersion
headerName: headerValue
...
headerNameN: headerValueM
Optional Body
...

Example with a get request

GET https://datacadamia.com/web/http/method HTTP/1.1
Host: datacadamia.com
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.150 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: https://datacadamia.com/web/http/method
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9,nl;q=0.8,fr;q=0.7
Cookie: Session=2he81i5j7tvd5

List non-exhaustive of headers put on the request

What is the HTTP Host Header and how it is used? - the destination network location

Host: datacadamia.com

HTTP Connection management - the control of the TCP conenction

Connection: keep-alive

pragma (cache configuration)

Pragma: no-cache

Cache-control (cache configuration)

Cache-Control: no-cache

HTTP - User Agent Header

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.150 Safari/537.36

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9

The referer identifies the URL of the page where the request originated.

Referer: https://datacadamia.com/web/http/method

Cookie: name=value; _name=value1

Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9,nl;q=0.8,fr;q=0.7

Security Type

Same / Cross Origin

When the origin of the resource that created the request:

is not the same than the request origin, the request is called a cross-origin request
is the same than the request origin, the request is called a same-origin request