NOTE: To change the image on this slide, select the picture and delete it. Then click the Pictures icon in the placeholder to insert your own image. WEB TECHNOLOGY WEEK 1 Web Essentials Dr Sha

World wide web  The World Wide Web (WWW) is a system of interlinked hypertext documents accessed via the Internet.systemhypertextInternet  The World Wide Web (WWW) can be viewed as a huge distributed system consisting of millions of clients and servers for accessing linked documents. Servers maintain collections of documents, while clients provide users an easy-to-use interface for presenting and accessing those documents

HTTP Request The general form of the HTTP request is 1.HTTP method Domain part of the URLHTTP version 2.Header fields 3.Blank line 4.Message body HTTP request methods GET, HEAD, POST, PUT, DELETE. Example: GET /storefont.htmlHTTP/1.1

HTTP Response Messages The general form of the HTTP response is 1.Status line 2.Response Header field 3.Blank line 4.Response body Example: HTTP/ OK

Web servers Web servers are programs that provide documents to requesting browsers. Servers are slave programs that act only when the requests are made to them by browsers running on other computers on the internet. Example: Apache, IIS.

Web browsers Documents provided by servers on the web are requested by browsers which are programs running on the clients. Example: Internet Explorer, Google Chrome, Mozilla Firefox.

The internet The internet is the collection of computers and other devices connected by equipment that allows them to communicate with each other. The web is collection of software and protocols that has been installed on the internet.

Basic protocols In order for computers to communicate with one another, they must agree on a set of rules for who says what, when they say it, and what format they say it. This set of rules is a protocol. Example: HTTP, FTP, SMTP, TCP/IP.