Introduction to Computing

Following topics will be discussed during this session.

• Today's Goal
• World Wide Web
• Browser
• What is URL?
• How do I navigate the Web
• How many Web pages are there?
• What is a Web site?
• What is Web Search Engine?
• Internet ? Web
• What info is available on Web?
• Impact of Web on Computing
• Impact of Web on Society
• Impact of Web on Commerce
• Who invented the Web & Why?
• Key Weaknesses of Web
• The Future: The Semantic Web
• Summary
• Goals of next Lecture

Today's Goal

• Become familiar with one of the most popular activities on computers – the World Wide Web
• We want to Become familiar with the Web’s structure
• About how the Web works
• About its genesis, its evolution, and where it is going

What is World Wide Web?

· A huge resource of information

· Logically unified, but physically distributed

· Logically unified: Any one from any where can access the information using a very simple scheme consisting of links & URLs

· Physically distributed: The information is stored on Internet-connected computers that are spread all over the globe

Who is Allowed to access the Web?

• Any one and every one with a computer and a connection to the Internet
• No nationalistic, ideological, racial, or religious restrictions
• In Pakistan, Web is accessible from any city or town that has a phone available
  

The Web is unlike any previous human invention. Because it is a world-wide resource, important to all of the people in the world

How do I visit a Web page?

1. Turn your computer on
2. Connect to the internet through a modem or Local Area Network
3. Launch the browser (which in most cases, will be the Internet Explorer)

Type in the URL of the Web page that you want to visit

What is World Wide Web?

· A huge resource of information

· Logically unified, but physically distributed

· Logically unified: Any one from any where can access the information using a very simple scheme consisting of links & URLs

· Physically distributed: The information is stored on Internet-connected computers that are spread all over the globe

Who is Allowed to access the Web?

• Any one and every one with a computer and a connection to the Internet
• No nationalistic, ideological, racial, or religious restrictions
• In Pakistan, Web is accessible from any city or town that has a phone available
  

The Web is unlike any previous human invention. Because it is a world-wide resource, important to all of the people in the world

How do I visit a Web page?

1. Turn your computer on
2. Connect to the internet through a modem or Local Area Network
3. Launch the browser (which in most cases, will be the Internet Explorer)

Type in the URL of the Web page that you want to visit

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.

What is 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.google.com

How Do I navigate the Web?

You go from one Web page to another my clicking on a link.

For example, here is my Web page

• The underlined pieces of text in blue are called links
• Each link is a gateway to another Web page

All you have to do is click on the link to go to the page corresponding to that link

How many Web pages are there?

• In 1999 there were 800 million Web pages (15 terra (1012) bytes of text)
• In year 2002, the number is supposed to be 8 billion
• If you spend a minute reviewing each of these pages, it will take more than 15,000 years to go through them all.

What is secret behind the explosive growth of the Web?

• Anarchy – any page is allowed to link to any other
• There are no controls over who puts what on the Web

Everyone can put whatever they want to put on the Web – and they do!

DRAWBACKS:
- Inconsistent quality of pages
- Broken links

The most popular Web sites?

• AOL – Most popular ISP’s Web site

• Microsoft – Most popular software developer’s Web site
• Yahoo – Most popular multi-service Web site
• Amazon – most popular shop on the Web
• CNN – most popular news Web site

Google – most useful search engine

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.

What is a Web Search Engine?

· Search engines continuously scan the Web and compile a list of all the Web pages that they find

· The search engine with the largest such list (or index) is Google – with a list of over 2 billion Web pages and over 330 million images

· We use the search engine by typing a “search key word” or “query” on its Web page. It looks for those keyword in its index, and displays a list of Web pages that contain that keyword

I know I can read off the Web. Am I allowed to put my stuff on the Web?

• Yes. You just need to have a computer that is hooked up to the Internet.

· You do not require anyone’s permission to put your Web page(s) on the Web

· Your Web page will be available to all the millions of users that have access to the Internet the moment you place it on the Web

Internet & Web

• The “Internet” and the “Web” are not the same
• In fact, the “Web” is a service that runs over the “Internet”. In addition to the Web, there are many other services that run over the Interne.
• Internet is like the network of roads in a city, whereas Web is a service like the Bus Service that run over those roads. Just like other services can use the roads (e.g. wagons), so can other services on the Internet (e.g. ftp). We’ll have more to say about this later in the course

However, The following refer to the same thing:
World Wide Web, Web, WWW

Info is available on Web

• Information about almost every thing known to mankind and then some!

The info is in the form of:

– Text

– Graphics

– Animation

– Video

– Sound

Impact of Web on Computing

• Every one wants to use the Web
• That has spurred the demand for computers
• That, in turn, has reduced the cost of computing drastically
• The computers are becoming easier to use because the target users are becoming less and less sophisticated

In the olden times only techies used computers; now my 4-year old knows things about the machine that I never did

Impact of Web on Society

• User friendly communication has become much more affordable – the global village is shrinking

• Business persons can stay in touch with their businesses even without being there – for some, that has resulted in the destruction of their family life

Impact of Web on Commerce

• Huge impact
• The moment I take my business to the Web, it becomes possible for my customers to find out about me without me being physically present in their city

• Suddenly, I’m running a global business

Key Weaknesses of Web

• The Web (as it currently exists) was designed for human to read, not for computers to understand and manipulate meaningfully
• Computers have a great problem in dealing with the current text and graphics based Web

• Here is an example …

What’s the problem with this page?

• You (a human) see this page and immediately understand what my name is
• How would a computer know the same fact?
• For that, the computer needs some help

Some help in form of a statement:
-- Name=“Altaf Khan”
-- Occupation=“Teaching”
-- Employer=“Virtual University”
And so on

The Semantic Web

• What unique feature distinguishes the Web of today with the Semantic Web of tomorrow?
• Whereas, today’s Web’s content is designed for humans to read; the Semantic Web’s content will be designed for computers to understand meaningfully
• However, the Semantic Web is not a replacement but an extension of the present Web, in which information is given well defined meaning

Some progress is already being made for adding “Semantic Content” on to the Web, but a lot more will happen in next 5 (five) years.

To find further info about this exciting development read Tim Berner Lee and his co-worker’s paper: “The Semantic Web” that is available on the Web as:

http://www.sciam.com/2001/0501issue/0501berners-lee.html