Hyper Text Transfer Protocol (http)

Hyper Text Transfer Protocol or more commonly known as HTTP is the protocol used by the World Wide Web. HTTP defines how messages are formatted, transmitted and how web servers and browsers respond to various commands. For example, when you type a URL into a browser, you're actually sending a command to the web server instructing it to find and return the requested web page. Known as a stateless protocol, each command is executed independently with no knowledge of the prior command. Due to HTTP being a stateless protocol, web sites can't respond intelligently to user commands on input. The use of new technologies such as Active X, Java, Java Script, and cookies help HTTP overcome this command issue. HTTP is a TCP/IP based communication protocol; which is used to deliver virtually all files and other data called resources. A browser works as an HTTP client because it sends requests to an HTTP server which is called a web server. The standard port for a HTTP is 80, but it can be changed to other ports such as 8080. There are three important things about HTTP that a person should remember: HTTP is connectionless due to after a request is made, the client disconnects from the server and waits for a response. The server must re-establish connection after it processes the request. HTTP is media independent, any type of data can be sent by HTTP as long as both the client and server know how to handle the data content. HTTP is stateless. This is a result of HTTP being connectionless where the server and client are aware of each other only during a request, then forgetting each other. The HTTP message structure format is designed as listed:

Initial Line: Request line which has three parts separated by spaces.

Response Line: The response line called the status line also has three parts separated by spaces. Header Lines: provide information about the request or response. The Message Body: this is a body of data sent after the header lines. The set of common methods for HTTP are listed as:

The GET method means retrieve whatever information is identified by the request URL. The HEAD method is just like a GET request. But it only asks the server to return the response in headers only. The POST method is used to send data to the server to be processed in some way like a CGI script. A POST request is different from a GET request in the following ways:

A block of data is sent