HTTP BEHAVIORS
What is HTTP (Hypertext Transfer Protocol)?
The Hypertext Transfer Protocol is an application protocol for distributed, collaborative, hypermedia information systems that allows users to communicate data on the World Wide Web.
What is the purpose of HTTP?
HTTP was invented alongside HTML to create the first interactive, text-based web browser: the original World Wide Web. Today, the protocol remains one of the primary means of using the Internet.
Founder and Evolution of HTTP
The original HTTP proposal by Tim Berners-Lee was designed with simplicity in mind as to help with the adoption of his other nascent idea: the World Wide Web(www).
HTTP/0.9 was a wonderfully simple, if limited, protocol. It had a single method (GET), there were no headers, and it was designed to only fetch HTML.
Over the next few years, use of HTTP grew. By 1995 there were over 18,000 servers handling HTTP traffic on port 80 across the world. The protocol had evolved well past its 0.9 roots, and in 1996 RFC 19453 codified HTTP/1.0.
Over the next few years, the work on turning HTTP into an official IETF Internet standard proceeded in parallel with the documentation effort around HTTP/1.0 and happened over a period of roughly four years: between 1995 and 1999. In fact, the first official HTTP/1.1 standard is defined in RFC 2068, which was officially released in January 1997, roughly six months after the publication of HTTP/1.0. Then, two and a half years later, in June of 1999, a number of improvements and updates were incorporated into the standard and were released as RFC 2616.
In early 2012, the HTTP working group (the IETF group responsible for the HTTP specifications) was re chartered to work on the next version of HTTP.
It is expected that HTTP/2.0 will:
Substantially and measurably improve end-user perceived latency in most cases, over HTTP/1.1 using TCP.
Address the “head of line blocking” problem in HTTP.
Not require multiple connections to a server to enable parallelism, thus improving its use of TCP, especially regarding congestion control.
Retain the semantics of HTTP/1.1, leveraging existing documentation (see above), including (but not limited to) HTTP methods, status codes, URIs, and header fields.
Clearly define how HTTP/2.0 interacts with HTTP/1.x, especially in intermediaries (both 2->1 and 1->2).
Clearly identify any new extensibility points and policy for their appropriate use.
A call for proposals was sent out and it was decided to use SDPY as a starting point for HTTP/2.0. Finally, on May 14, 2015, RFC 7540 was published and HTTP/2 was official.
How HTTP works
HTTP is an application layer protocol built on top of TCP that uses a client-server communication model. HTTP clients and servers communicate through request-and-response messages. The three main HTTP message types are GET, POST, and HEAD.
HTTP GET:
messages sent to a server contain only a URL. Zero or more optional data parameters may be appended to the end of the URL. The server processes the optional data portion of the URL, if present, and returns the result (a web page or element of a web page) to the browser.
HTTP POST :
messages place any optional data parameters in the body of the request message rather than adding them to the end of the URL.
HTTP HEAD :
requests work the same as GET requests. Instead of replying with the full contents of the URL, the server sends back only the header information (contained inside the HTML section).
The browser initiates communication with an HTTP server by initiating a TCP connection to the server. Web browsing sessions use server port 80 by default, although other ports such as 8080 are sometimes used instead.
After a session is established, you trigger the sending and receiving of HTTP messages by visiting the web page.
HTTP is what’s called a stateless system. What this means is that unlike other file transfer protocols such as FTP, the HTTP connection is dropped after the request has been completed. So, after your web browser sends the request and the server responds with the page, the connection is closed.