16 June 2012

SHORT INTRODUCTION ABOUT HTTP

ANSWER:-
HTTP stands for hypertext transfer protocol.
SHORT HISTORY:-
The term HyperText was coined by Ted Nelson who in turn was inspired by Vannevar Bush's microfilm-based "memex". Tim Berners-Lee first proposed the "WorldWideWeb" project — now known as the World Wide Web.
Berners-Lee and his team are credited with inventing the original HTTP along with HTML and the associated technology for a web server and a text-based web browser.The first version of the protocol had only one method, namely GET, which would request a page from a server.The response from the server was always an HTML page.

REQUEST METHODS OR PROCESSING METHODS:-
HTTP defines nine methods indicating the desired action to be performed on the identified resource. What this resource represents, whether pre-existing data or data that is generated dynamically, depends on the implementation of the server. Often, the resource corresponds to a file or the output of an executable residing on the server.

HEAD:-
    Asks for the response identical to the one that would correspond to a GET request, but without the response body. This is useful for retrieving meta-information written in response headers, without having to transport the entire content.

GET:-
    Requests a representation of the specified resource. Requests using GET should only retrieve data and should have no other effect.The W3C has published guidance principles on this distinction, saying, "Web application design should be informed by the above principles, but also by the relevant limitations."

POST:-
    Submits data to be processed to the identified resource. The data is included in the body of the request. This may result in the creation of a new resource or the updates of existing resources or both.

PUT:-
    Uploads a representation of the specified resource.

DELETE:-
    Deletes the specified resource.

TRACE:-
    Echoes back the received request, so that a client can see what changes or additions have been made by intermediate servers.

OPTIONS:-
    Returns the HTTP methods that the server supports for specified URL. This can be used to check the functionality of a web server by requesting '*' instead of a specific resource.

CONNECT:-
    Converts the request connection to a transparent TCP/IP tunnel, usually to facilitate SSL-encrypted communication (HTTPS) through an unencrypted HTTP proxy.

PATCH:-
    Is used to apply partial modifications to a resource.

HTTP servers are required to implement at least the GET and HEAD methods and, whenever possible, also the OPTIONS method.


SAFE MODE:-
Some methods are defined as safe, which means they are intended only for information retrieval and should not change the state of the server. In other words, they should not have side effects, beyond relatively harmless effects.

IDEMPOTENT METHODS:-

Methods PUT and DELETE are defined to be idempotent, meaning that multiple identical requests should have the same effect as a single request Methods GET, HEAD, OPTIONS and TRACE, being prescribed as safe, should also be idempotent, as HTTP is a stateless protocol.

STATUS OR ERROR CODES:-
REFER STATUS OR ERROR CODE PAGE.

NOTE:- this short introduction is taken from Wikipedia and just short introduction if you are interested in knowing this in deep click here.

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