HTTP Revised:

In this, it describes the HTTP protocol in more details. In particular, it does define the structure of the request and response streams.

Hypertext Transfer Protocol (HTTP):

  • In any communication protocol, the client must transmit a request and the server should transmit some meaningful response.
  • In HTTP, request is some resource that is specified by the URL. If the URL is specified by some static document, then the response includes the text of that document.
  • You can think of the request and response as envelopes around the URL (plus form data)and the response text.
  • The figure given below does show the client server architecture:

 

Design View Components: Client Server Architecture

 

HTTP Methods:

An HTTP request can be made using a variety of methods. The table given below lists the HTTP methods and their descriptions.

HTTP Method Description
OPTIONS Request for the communication options available on the request/response chain
GET Request to retrieve an information identified by the request URI
HEAD Identical to the GET except that it does not return a message body, only a  headers
POST Request for the server to accept the entity enclosed In the body of the HTTP response
PUT Request for the server to store the entity enclosed In the body of the HTTP response
DELETE Request for the server to delete the resource identified by the Request URI
TRACE Request for the server to invoke an application layer loop back of the request message
CONNECT Reserved for use with a proxy that can switch to being a tunnel

 

HTTP GET Method:

  • The most common HTTP method is the GET request. The GET method is used whenever an user clicks a hyperlink in the HTML page currently being viewed.
  • A GET method is also used when the user enters a URL into the Location field (for Netscape Navigator and Firefox) or the Address field (for Microsoft Internet Explorer).
  • While processing a web page, the browser also issues GET requests for images, applets, style sheet files, and other linked media.

HTTP Request:

  • The request stream acts as an envelope to the URL and message body of the HTTP client request.
  • The first line of the request stream is called the request line. It includes the HTTP method (usually either GET or POST), followed by a space character, followed by a requested URL (usually a path to the static file), followed by the space, and finally followed by the HTTP version number.
  • The request header includes the header name (for example User agent), followed by a colon character (and space), and followed by the value of the header.
  • The list of headers ends witha blank line. After the blank line, there is an optional message body.
  • The figure given below shows an example HTTP request stream.

 

Designing view component : HTTP Request Stream Example

 

HTTP Request Stream Example

HTTP Request Headers:

The table given below illustrates some of the HTTP headers that the browser can place in the request. The headers could then be used to determine how the server processes the request.

Some HTTP Request Headers:

Header Use
Accept The MIME types the client can receive
Host The internet host and port number of the resource being requested
Referrer The address from which the request URI was obtained
User Agent The information about the client originating the request

 

HTTP Response:

  • The response stream acts as an envelope to the message body of the HTTP server response. The first line of the response stream is called the status line.
  • The status line includes the HTTP version number, followed by the space, followed by numeric status code of the response, followed by the space, and finally followed by the short text message represented by the status code.
  • The status line is followed by any number of response header lines.The response headers conform to the same structure as request headers.
  • The figure given below shows an example HTTP response stream.

 

Design view component : HTTP Response Stream Example

 

HTTP Response Stream Example

HTTP Response Headers:

The table given below illustrates some of the HTTP headers that the server can place in the response. The headers could then be used to determine how the browser processes the response.

Some HTTP Response Headers:

Header Use
Content-Type A MIME type (such as text/html), which classifies the type of the data in the response
Content-Length The length (in bytes) of the payload of the response
Server An informationalstring about the server that responded to this HTTP request
Cache Control A directive for the web browser (or proxies) to indicate whether the content of the response should be cached.

 

In this way, you can use HTTP request and response headers.

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Written by Sourabh Bhunje

Sourabh Bhunje, B.E. IT from Pune University. Currently Working at Techliebe. Professional Skills: Programming - Software & Mobile, Web & Graphic Design, Localization, Content Writing, Sub-Titling etc. http://techliebe.com/about-us

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