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protocols:http [2026/06/26 15:18] – [HTTP Request Message] v1ctorprotocols:http [2026/07/01 14:08] (current) – [Intro] v1ctor
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 ====== HTTP ====== ====== HTTP ======
  
-==== Intro ====+===== Intro =====
  
 HTTP can run in two modes: HTTP can run in two modes:
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 Both have a start line, headers, an empty line and optional body. Both have a start line, headers, an empty line and optional body.
-==== HTTP Request Message ====+ 
 +**Version** - the application doesn't usually care which protocol version is being used. The web-server translates the protocol details into standard request before passing it to the application. 
 + 
 +The version is **negotiated** during TLS handshake. The browser advertises the application protocols it supports using TLS extension called ALPN. 
 + 
 +There is no TLS handshake for HTTP, so the browser simply starts with **HTTP/1.1**.  
 + 
 +**HTTP/3**\\ 
 +HTTP/3 runs on top of the QUIC (Quick UDP). The main idea that we eliminate two handshaks that were needed in HTTPs (TCP + TLS). 
 + 
 +In QUIC TLS handshake is absorbed into the initial setup handshake. HTTP/3 does not run TLS "on top" of QUIC. Instead, **TLS 1.3** is built into the QUIC protocol itself. 
 + 
 +QUIC mitigates HOL (Head of Line) problem by treating each stream within a single connection independently. If one particular frame is lost, QUIC will handle it separately without blocking the rest of the streams. 
 + 
 +===== HTTP Request Message =====
  
 First line in the Request Message is called a **request** line. The subsequent lines are called **headers** line. First line in the Request Message is called a **request** line. The subsequent lines are called **headers** line.
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 First line in Response Message is called a **status** line. Then we have six **header** lines and then **entity body**. First line in Response Message is called a **status** line. Then we have six **header** lines and then **entity body**.
 +
 +Status line has three fields:
 +  - Protocol version
 +  - Status code
 +  - Corresponding status message
 +
 +==== Cookie ====
 +
 +HTTP is a Stateless protocol. Cookie is the primary mechanism for maintaining state. Cookies allows a web server to know:
 +  * Whether you've visited before
 +  * Whether you're logged in
 +  * What's in your shopping cart
 +  * What language you selected
protocols/http.1782487084.txt.gz · Last modified: by v1ctor