HTTP By Mychal Hess, Dee Chow, and Riley Barnes

History HTTP  Tim Berners-Lee he implemented the HTTP protocol in 1990 at the European Center for High- Energy Physics in Geneva, Switzerland.  He invented a new protocol for the computers to speak as they exchanged hypermedia documents. This allows the communication between http clients with http servers.  The HTTP protocol uses the concept of reference provided by the Universal Resource Identifier (URI) as a location (URL) or name (URN), for indicating the resource on which a method is to be applied.

HTTP  HTTP stands at the very core of the World Wide Web. According to the HTTP 1.0 specification, HTTP is an application-level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems.  It is stateless: After the server has responded to the client's request, the connection between client and server is dropped and forgotten.

What Does it Look Like? Request Line Response Line Allows communication of HTTP Client with HTTP Server through a browser

How It Works  Client initiates process  Sender process consists of three stages: Request Line Header Information Stage Body of Request Stage

Request Stage  Client sends out request to receiver  Request stage contains three parts First part is called the method Three main methods of request:  Get method: Receive information from server  Head method: Ask for information about server or particular file  Post method: Allows data to be sent from sender to receiver

Request Stage  Second part of request stage sends out Uniform Resource Locator (URL) to server  This includes name of server  Followed by name of file  Followed by the parameter information ProtocolServer NameFile Name Parameter Info Third Part sends out HTTP version that the server needs to reply with

Header Info and Body  The second stage header information is sent  The sender gives its user agent, i.e. what browser it’s using (Internet explorer, Mozilla, etc.)  Gives its preference for document types, such as pictures in JPEG, GIF, or PJPEG Format  Lastly, internet cookies are exchanged during this stage in the process  Third and final stage contains the body of the request

Response Line  Version of HTTP  Code which indicates success of request  200= Successful  400= Bad Request  403= Access Denied  404= File not found  402= Payment Required  Text indicating meaning of code

Response Line (Cont.)  Response Headers  Version of HTTP  Content Type: HTML, Mp3, JPEG  Bytes

Response Line (Cont.)  Body eg: Map Starts Over Stateless Protocol

Cookies  Cookies are short pieces of data used by web servers to help identify web users.  Cookies are embedded in the HTML information flowing back and forth between the user's computer and the servers.  Cookies make use of user-specific information transmitted by the Web server onto the user's computer so that the information might be available for later access by itself or other servers.

Process of Cookie  Two-stage process  First the cookie is stored in the user's computer.  Second stage the cookie is automatically transferred from the user's machine to a Web server.

Dangers of Cookies  In most cases, not only does the storage of personal information into a cookie go unnoticed, so does access to it. Web servers automatically gain access to relevant cookies whenever the user establishes a connection to them  Some people may find this invasive to their privacy, but usually the use of this information is harmless