Title: CS101 Introduction to Computing Lecture 3 The World Wide Web (Web Development Lecture 1)
1CS101 Introduction to ComputingLecture 3The
World Wide Web(Web Development Lecture 1)
2During the Last Lecture
- We learnt about some of the important milestones
on the journey that started from the Analytical
Engine and so far has taken us to the portable
computer-telephone of today - We also saw how computing transitioned from
mechanical to electro-mechanical to tube to
transistor technology and now is poised to take a
breathtaking twist towards quantum computing
3Todays Goal is to
- Become familiar with one of the most popular
activities on computers the World Wide Web - Become familiar with the Webs structure and how
the Web works - Learn about its genesis, its evolution, and its
future - About its impact on computing, society, commerce
4What is the World Wide Web?
- A huge resource of information
- Logically unified, but physically distributed
- Unified Anyone from any where can access the
information using a very simple scheme consisting
of hyperlinks URLs - Distributed The info is stored on
Internet-connected computers that are spread all
over the globe
5Who is allowed to access the Web?
- Anyone 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
6The Web is unlike any previous human
inventionBecause it is a world-wide resource,
important to all and shared by all of the people
in the worldEnough about who can access it.
Now let us focus upon how to access itAs some
of you may know, the Web is a collection of Web
pages accessing the Web means accessing one of
those Web pages
7How do I access/visit a Web page?
- Turn your computer on
- Connect to the Internet through a modem or
through your computer network - Launch the browser
- Type in the URL of the Web page that you want to
visit
8Browser
- The tool used for accessing the content of the
Web - Browser and the content of the Web have the same
relationship as the TV has with TV programs - 1993 - The 1st major browser Mosaic was
developed at the National Center for
Supercomputing Applications (NCSA) at the
University of Illinois, Urbana-Champaign - Initially handled text only, later
graphics-viewing capability was added - Most popular Internet Explorer, Netscape
Navigator
9What is a URL?
- Universal Resource Locator
- The unique address assigned to each unique page
on the Web - Examples
- http//dawn.com
- http//www.vu.edu.pk/altaf
- http//www.smeda.org.pk
10Are there any access charges?
- Most of the info on the Web is available for free
- There is some for-payment content on the Web,
which is generally paid with the help of a credit
card
11How do I navigate the Web?
- You go from one Web page to another my clicking
on a hyperlink - Ill explain it to you through the example of my
own Web page
12URL
links
13Hyperlinks
- The underlined pieces of text in blue are called
hyperlinks - Each hyperlink is a gateway to another Web page
- All you have to do is click on the hyperlink to
go to the page corresponding to that hyperlink
14How many Web pages are there?
- In 1999 there were 800 million Web pages (15
trillion (1012) text characters) - In the year 2002, the number is estimated 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
15Tum salamat raho hazar barasHer baras kay hon
din pachas hazar(140,000 normal years)
16What 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
17Some of the popular Web sites?
- AOL Most popular ISPs Web site
- Microsoft Most popular software developers 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
18What is a Web site?
- A collection of related documents available on
the Web - The first portion of the URLs in the Web pages of
a Web site is the same e.g. - http//www.vu.edu.pk/
- http//www.vu.edu.pk/altaf
- http//www.vu.edu.pk/cs101
- are the URLs of three distinct Web pages on a
single Web site
19What is a home page?
- The first, top-most page of a Web site, just like
the cover of a magazine - VUs home page is at http//www.vu.edu.pk
20What is a Search Engine?
- They continuously scan the Web and compile a list
of all the Web pages keywords found on those
pages - 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 keyword 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
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24I know I can read off the Web. Am I allowed to
put my stuff on the Web?
- Definitely. You just need to have a computer
that is hooked up to the Internet. - You do not require anyones 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
25Am I allowed to put my stuff on the Web? (cont.)
- Next week youll have the opportunity to do just
that - Youll learn how to develop your own Web page
- And how to make it available on the Web
26Internet ---- Web
?
27- 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 Internet - 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). Well
have more to say about this later in the course - However, The following refer to the same thing
- World Wide Web, Web, WWW
28What info is available on the Web?
- Information about almost every thing known to
mankind and then some! - The info is in the form of
- Text
- Graphics
- Animation
- Video
- Sound
29- Impact of the Web on
- Computing
- Society
- Commerce
30Impact of the Web on Computing(Cost)
- Every one wants to use the Web
- That has spurred the demand for computers
- That, in turn, has reduced the cost of computers,
software, and Internet access drastically
31Impact of the Web on Computing(Ease of use)
- 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 and probably, never will
32Impact of the 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
33Impact of the Web on Commerce
- Huge impact
- The moment I take my business to the Web, it
becomes possible for my customers even those
that I do not know about - to find out about me
without me being physically present in their city - Suddenly, Im running a global business
34Who invented the Web Why?
- Tim Berners Lee British physicist
- 1989 At the European Center for Nuclear Energy
Research (CERN) in Geneva - He just wanted a way by which scientists could
easily share documents over computer networks
35 The key weakness of the Web?
- The Web (as it currently exists) was designed for
humans to read, not for computers to understand
and manipulate meaningfully - Computers face great problems in dealing with the
current text- and graphics-based content of the
Web - Here is an example from my own Web page
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37Whats 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 in form of
a statement - NameAltaf Khan
- OccupationTeaching
- EmployerVirtual University
- And so on
38Precisely for this reason, the Web of the future
will be different from the Web of todayThe Web
of the future will be called the Semantic Web
39Future of the Web Semantic Web
- What unique feature distinguishes the Web of
today with the Semantic Web of tomorrow? - Whereas, todays Webs content is designed for
humans to read the Semantic Webs 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
40The Semantic Web
- Some progress is already being made for adding
Semantic Content on to the Web, but a lot more
will happen in the next 5 years - To find further info about this exciting
development read Tim Berners Lee and his
co-workers paper The Semantic Web that is
available on the Web as - http//www.sciam.com/2001/0501issue/0501berners-le
e.html
41Another useful Web page
- Web page for our Understanding Computers text
book - http//www.hbcollege.com/infosys/parker2000
42What 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
43Goal of the Next Lecture
- To become familiar with various types of
computers with respect to their applications and
scale - To become familiar with the basic components of a
computer