Introduction to Web Technology: Understanding the Fundamentals of the World Wide Web, Lecture notes of Computer Science

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Introduction to

Web Technology

Unit 1

Introduction

WWW

• Affectionately called “The Web”
• It is a collection of information stored on the networked computers over the world.
• Individual document pages on the World Wide Web are called web pages and are accessed with a software application running on the user's computer, commonly called a web browser.
• Web pages may contain text, images, videos, and other multimedia components, as well as web navigation features consisting of hyperlinks.
• The WWW was proposed in 1991 by Tim Berners-Lee at CERN

Web Terminologies Client : Any computer on the network that requests services from another computer on the network. Server : Any computer that receives requests from client computers, processes and sends the output. Web Page : Any page that is hosted on the Internet. Web Site : Collection of interlinked web pages that is hosted on the Internet. Web Development : The process of creating, modifying web pages. Web Browser : A program that receives information from the web. E.g. IE, Chrome, Mozilla etc

Web Application- Client Side and Server side

• Web development is all about communication and data exchange.
• This communication takes place via two parties over the HTTP protocol.
• These parties are:
• Server : The Server is responsible for serving the web pages depending on the client/end-user requirement. It can be either static or dynamic.
• Client : A client is a party that requests pages from the server and displays them to the end-user. In general a client program is a web browser.

Fetching Pages over the Internet

• Architecturally, the Internet consists of a collection of layers, each one providing services for the one above it: - The Internet Layer gets packets to their destinations; The Transport Layer sends streams of data; - The Application Layer provides high-level services to applications such as Web browsers.

SSL

• Secure Socket Layer Protocols:
  • SSL record protocol
  • Handshake protocol
  • Change-cipher spec protocol
  • Alert protocol
• SSL Protocol Stack:

Uniform Resource Locators (URLs) Without a universal addressing mechanism, it would be impossible to navigate to a site, and page linking would not be feasible Uniform Resource Locators (URLs) are used to identify Web pages — basically a URL is a web address URLs have 3 components: A Prefix (usually http:// ) A Hostname: (such as www.cityu.edu.hk) A Path: (such as /scm/index.htm)