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Introduction to Computing

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Introduction to Computing ­ CS101
VU
LESSON 3
Today's Goal is to ...
Become familiar with the World Wide Web
Become familiar with the Web's structure and how the Web works
Learn about its genesis, its evolution, and its future
About its impact on computing, society, commerce
3.1
Browser
A browser is an application program that provides a way to look at and interact with all the information
on the World Wide Web. The word "browser" seems to have originated prior to the Web as a generic
term for user interfaces that let you browse (navigate through and read) text files online. By the time the
first Web browser with a graphical user interface was generally available (Mosaic, in 1993), the term
seemed to apply to Web content, too. Technically, a Web browser is a client program that uses the
Hypertext Transfer Protocol (HTTP) to make requests of Web servers throughout the Internet on behalf
of the browser user.
3.2 URL
URL (Uniform Resource Locator, previously Universal Resource Locator) - pronounced YU-AHR-EHL
or, in some quarters, UHRL - is the address of a file (resource) accessible on the Internet. The type of
file or resource depends on the Internet application protocol. Using the World Wide Web's protocol, the
Hypertext Transfer Protocol (HTTP), the resource can be an HTML page (like the one you're reading),
an image file, or any other file supported by HTTP. The URL contains the name of the protocol required
to access the resource, a domain name that identifies a specific computer on the Internet, and a
pathname (hierarchical description of a file location) on the computer.
On the Web (which uses the Hypertext Transfer Protocol), an example of a URL is:
http://www.ietf.org/rfc/rfc2396.txt
Which describes a Web page to be accessed with an HTTP (Web browser) application that is located on
a computer named www.ietf.org. The pathname for the specific file in that computer is /rfc/rfc2396.txt.
An HTTP URL can be for any Web page, not just a home page, or any individual file.
Examples:
http://dawn.com
http://www.vu.edu.pk
http://www.smeda.org.pk
3.3 What is a Web site?
A Web site is a related collection of World Wide Web (WWW) files that includes a beginning file
called a home page. A company or an individual tells you how to get to their Web site by giving you the
address of their home page. From the home page, you can get to all the other pages on their site. For
example, the Web site for IBM has the home page address of http://www.ibm.com. IBM's home page
address leads to thousands of pages but a web site can also be just of few pages.
http://www.vu.edu.pk/
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Introduction to Computing ­ CS101
VU
3.4 What is Home Page of a web site?
1) For a Web user, the home page is the first Web page that is displayed after starting a Web browser
like Netscape's Navigator or Microsoft's Internet Explorer. The browser is usually preset so that the
home page is the first page of the browser manufacturer. However, you can set it to open to any Web
site. For example, you can specify that "http://www.yahoo.com" or "http://whatis.com" be your home
page. You can also specify that there be no home page (a blank space will be displayed) in which case
you choose the first page from your bookmark list or enter a Web address.
2) For a Web site developer, a home page is the first page presented when a user selects a site or
presence on the World Wide Web. The usual address for a Web site is the home page address, although
you can enter the address (Uniform Resource Locator) of any page and have that page sent to you.
3.5 Who invented the Web & Why?
"CERN is a meeting place for physicists from all over the world, who collaborate on complex physics,
engineering and information handling projects. Thus, the need for the WWW system arose "from the
geographical dispersion of large collaborations, and the fast turnover of fellows, students, and visiting
scientists," who had to get "up to speed on projects and leave a lasting contribution before leaving."
CERN possessed both the financial and computing resources necessary to start the project. In the
original proposal, Berners-Lee outlined two phases of the project:
First, CERN would "make use of existing software and hardware as well as implementing simple
browsers for the user's workstations, based on an analysis of the requirements for information access
needs by experiments."
Second, they would "extend the application area by also allowing the users to add new material."
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Introduction to Computing ­ CS101
VU
Berners-Lee expected each phase to take three months "with the full manpower complement": he was
asking for four software engineers and a programmer. The proposal talked about "a simple scheme to
incorporate several different servers of machine-stored information already available at CERN."
Set off in 1989, the WWW quickly gained great popularity among Internet users. For instance, at 11:22
am of April 12, 1995, the WWW server at the SEAS of the University of Pennsylvania "responded to
128 requests in one minute. Between 10:00 and 11:00
3.6 Future of the Web: Semantic Web
The Semantic Web is an idea of World Wide Web inventor Tim Berners-Lee that the Web as a whole
can be made more intelligent and perhaps even intuitive about how to serve a user's needs. Berners-Lee
observes that although search engines index much of the Web's content, they have little ability to select
the pages that a user really wants or needs. He foresees a number of ways in which developers and
authors, singly or in collaborations, can use self-descriptions and other techniques so that context-
understanding programs can selectively find what users want.
3.7 Useful Web page
Web page for our "Understanding Computers" text book
http://www.hbcollege.com/infosys/parker2000
What have we learnt today?
What is the World Wide Web?
How does it work?
About its expected evolution into the Semantic Web
The impact of the Web on computing, society, and commerce
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Table of Contents:
  1. INTRODUCTION
  2. EVOLUTION OF COMPUTING
  3. World Wide Web, Web’s structure, genesis, its evolution
  4. Types of Computers, Components, Parts of Computers
  5. List of Parts of Computers
  6. Develop your Personal Web Page: HTML
  7. Microprocessor, Bus interface unit, Data & instruction cache memory, ALU
  8. Number systems, binary numbers, NOT, AND, OR and XOR logic operations
  9. structure of HTML tags, types of lists in web development
  10. COMPUTER SOFTWARE: Operating Systems, Device Drivers, Trialware
  11. Operating System: functions, components, types of operating systems
  12. Forms on Web pages, Components of Forms, building interactive Forms
  13. APPLICATION SOFTWARE: Scientific, engineering, graphics, Business, Productivity, Entertainment, Educational Software
  14. WORD PROCESSING: Common functions of word processors, desktop publishing
  15. Interactivity to Forms, JavaScript, server-side scripts
  16. ALGORITHMS
  17. ALGORITHMS: Pseudo code, Flowcharts
  18. JavaScript and client-side scripting, objects in JavaScript
  19. Low, High-Level, interpreted, compiled, structured & object-oriented programming languages
  20. Software Design and Development Methodologies
  21. DATA TYPES & OPERATORS
  22. SPREADSHEETS
  23. FLOW CONTROL & LOOPS
  24. DESIGN HEURISTICS. Rule of thumb learned through trial & error
  25. WEB DESIGN FOR USABILITY
  26. ARRAYS
  27. COMPUTER NETWORKS: types of networks, networking topologies and protocols
  28. THE INTERNET
  29. Variables: Local and Global Variables
  30. Internet Services: FTP, Telnet, Web, eMail, Instant messaging, VoIP
  31. DEVELOPING PRESENTATIONS: Effective Multimedia Presentations
  32. Event Handlers
  33. GRAPHICS & ANIMATION
  34. INTELLIGENT SYSTEMS: techniques for designing Artificial Intelligent Systems
  35. Mathematical Functions in JavaScript
  36. DATA MANAGEMENT
  37. DATABASE SOFTWARE: Data Security, Data Integrity, Integrity, Accessibility, DBMS
  38. String Manipulations:
  39. CYBER CRIME
  40. Social Implications of Computing
  41. IMAGES & ANIMATION
  42. THE COMPUTING PROFESSION
  43. THE FUTURE OF COMPUTING
  44. PROGRAMMING METHODOLOGY
  45. REVIEW & WRAP-UP of Introduction to Computing