HTTP Messages - HTTP

What are the Messages of HTTP?

HTTP is primarily based at the purchaser-server architecture model and a stateless request/reaction protocol that operates with the aid of exchanging messages across a reliable TCP/IP connection.

An HTTP "client" is an application (net browser or another client) that establishes a connection to a server for the reason of sending one or extra HTTP request messages. An HTTP "server" is a software ( usually a web server like Apache net Server or internet statistics services IIS, etc. ) that accepts connections with a purpose to serve HTTP requests by using sending HTTP reaction messages.

HTTP makes use of the Uniform aid Identifier (URI) to become aware of a given useful resource and to set up a connection. Once the connection is hooked up, HTTP messages are handed in a layout similar to that used by the internet mail [RFC5322] and the multipurpose internet Mail Extensions (MIME) [RFC2045]. Those messages encompass requests from patron to server and responses from server to patron that allows you to have the subsequent format:

HTTP requests and HTTP responses use a generic message format of RFC 822 for transferring the required data. This generic message format consists of the following four items.

  • A Start-line
  • Zero or more header fields followed by CRLF
  • An empty line (i.e., a line with nothing preceding the CRLF)
  • Indicating the end of the header fields
  • Optionally a message-body

In the following sections, we will explain each of the entities used in an HTTP message.

Message Start-Line

A start-line will have the following generic syntax:

We can speak Request-Line and status-Line at the same time as discussing HTTP Request and HTTP response messages respectively. For now, let's examine the examples of place to begin in case of request and response:

Header Fields

HTTP header fields offer required records approximately the request or reaction, or approximately the object sent in the message frame. There are four sorts of HTTP message headers:


These header fields have standard applicability for each request and reaction messages.


These header fields have applicability simplest for request messages.


These header fields have applicability most effective for response messages.


These header fields outline Meta records about the entity-body or, if nobody is gift, approximately the resource identified by means of the request.

All of the above cited headers observe the identical universal layout and each of the header field includes a call followed by means of a colon (:) and the field fee as follows:

Following are the examples of various header fields:

Message Body

The message frame element is optionally available for an HTTP message however if its miles to be had, then it is used to hold the entity-frame associated with the request or reaction. If entity frame is associated, then typically content material-kind and content-duration headers lines specify the nature of the body associated.

A message frame is the only which incorporates the actual HTTP request records (including form facts and uploaded, and so forth.) and HTTP response statistics from the server (including files, snap shots, and so on.). Proven underneath is the easy content of a message frame:

Next two chapters will make use of above explained concepts to prepare HTTP Requests and HTTP Responses.

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