2.5 HTTP  

2.5.1 Introduction to HTTP 

The Hypertext Transfer Protocol (HTTP) defines how client and server applications 

communicate in order to transfer hypertext documents and other resources located on the 

Internet although it is not specifically limited to the TCP/IP protocol stack. The protocol is 

independent of the type of resources transferred so data may be text, sound, images, query 

results from a database or even an application to be executed on the client machine.  

The Hypertext Transfer Protocol (HTTP) is an application level protocol for distributed, 

collaborative, hypermedia information systems. It is a generic, stateless, protocol which can 

be used for many tasks beyond its use for hypertext, such as name servers and distributed 

object management systems, through extension of its request methods, error codes and 

headers. A feature of HTTP is the typing and negotiation of data representation, allowing 

systems to be built independently of the data being transferred [15]. 

The format of a typical HTTP request response is as follows 

1. A client opens a connection with a server.  

2. The client sends a request to the server. This request consists of a request method, URI, 

and protocol version, followed by a MIME like message containing request modifiers, 

client information, and possible entity body content over a connection with a server. 

3. The server returns to the client a status line, header information, and possibly some entity 

metainformation and an entity body. 

4. The server closes the connection.  

HTTP is a stateless protocol in that it does not maintain any connection information between 

transactions although HTTP/1.1 does support persistent connections so a connection does 

not have to open each time to the fetch each URL and in doing so reduces the load on the 

server. This means that if a hypertext page has embedded references to other resources, the 

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