Transcript The Internet and the WWW

The Internet and
World Wide Web
The Internet
What are some services
found on the Internet?
(1)
(4)
(3)
(2)
(5)
(6)
 e-mail (1)
 chat (4)
 Web (2)
 message board (5)
 file transfer (3)  instant messaging (6)
History of the Internet
How did the Internet originate?
ARPANET
Goal:
To allow
scientists at
different
locations to share
information
Networking project
by Pentagon’s
Advanced Research
Projects Agency
(ARPA)
Goal:
To function if
part of network
were disabled
Became
functional
September
1969
During the
Cold War there
was concern
about
connectivity in
the event of a
nuclear attack
History of the Internet
 Early 1960’s
 Packet-switching envisioned (Baran and Davies)
 Divide a message into a smaller pieces called
packets.
 Each packet contains where they came from
and the address of where they are going.
 Each packet is sent to its destination
separately.
 Provided the foundation for what became the
Internet.
History of the Internet
 ARPANET (Advanced Research Projects Agency
NETwork)
 Funded by ARPA.
 Pooled computer scientists and resources from
several universities.
 In 1969, linked 4 nodes at UCLA, UC Santa
Barbara, SRI (Stanford Research Institute) and
Univ. of Utah.
 By mid-1970’s, linked several military sites and
about 20 universities.
History of the Internet
 NSF (National Science Foundation)
 In 1980, started CSnet.
 Provided a resource sharing network for
computer science research at all universities.
 Used TCP/IP protocol – the government gave it
away – it is in the public domain – no charge for
its use – UNIX based.
History of the Internet
 In 1989, majority of ARPANET switched to
NSF’s backbone.
 Became what is known as the Internet.
 Early 1995, the Internet became known as
the “Information Superhighway.”
History of the Internet
How has the Internet grown?
Today
More than 100 million host nodes
1984
More than 1,000 host nodes
1969
Four host nodes
History of the Internet
Who provides the Internet’s structure today?
Networks from
corporations,
commercial
firms, and other
companies
Telephone
companies
Satellite
companies
Cable
companies
Government
History of the Internet
Who controls the Internet?
 Nobody; it is public, cooperative, and an independent
network
 Several organizations set standards
World Wide Web Consortium
(W3C)
• Oversees research, sets
standards and guidelines
• Tim Berners-Lee, director
Internet2 (I2)
• Internet-related research
and development project
• Develops and tests
advanced Internet
technologies
How the Internet Works
What are ways to access the Internet?
1 Regional
ISP
2 National
ISP
3 OSP
(Ex. AOL)
4 Wireless
Internet
Service
Provider
2
1
local
call
long-distance
call
local
call
3
local
call
toll-free
call
4
local
call
How the Internet Works
How can you connect to the Internet?
Very high-speed connection
T-1, Fiber Optic
Digital subscriber line (DSL) and cable modem
Dial-up access
How the Internet Works
What are three parts of an Internet connection?
Client
(Your computer)
Backbone
(Communication
Lines)
Server
(Host computers)
How the Internet Works
1: RHow
equest
datadata
fromtravel
the the Internet using a telephone line connection?
might
a server on Internet.
2: Modem converts digital
signals to analog signals.
3: Data travels through
Regional
ISP
Step 3
Step 5
Step 1
telephone lines to a
local ISP.
4: Data passes
through routers.
Step 2
Step 4
National
ISP
5: Regional ISP uses
leased lines to send
data to a national ISP.
Local ISP
6: National ISP routes
data across the
country.
7: National ISP passes
data to local ISP.
8: Server sends
data back to you.
Step 6
Internet
backbone
Step 8
Step 7
National ISP
How the Internet Works

Internet owes its original critical mass to the wide distribution of
computers running the UNIX operating system.
 With the thousands of computers running the UNIX operating
system, and freely distributed TCP/IP software suite:
 Original access to the Internet had UNIX “feel.”
 Exact addresses were needed to access information.
 Addresses were strings of numbers
 Address for www.yahoo.com = 204.71.200.68
 You can find the Web server IP address by pinging the
site at the DOS command prompt.
 UNIX gurus “ran the net.” They loved the degree of
exclusivity due to the difficulty of use.
 This difficulty changed with development of “Gopher”
and later the WWW.
How the Internet Works
What is an Internet protocol (IP) address?
 Number that uniquely identifies each computer or device
connected to Internet
IP address
199.95.72.10
first part
identifies
network
last part
identifies
specific
computer
How the Internet Works

Networks using the TCP/IP protocol route messages
based on the IP address of the destination.
 Format of an IP address is a 32-bit numeric address
written as four numbers separated by periods.
 Each number can be zero to 255. For example,
1.160.10.240 could be an IP address.
 An isolated network, you can assign IP addresses at
random as long as each one is unique.
 Connecting a private network to the Internet requires
using registered IP addresses (called Internet
addresses) to avoid duplicates.
 The four numbers in an IP address are used in
different ways to identify a particular network and a
host on that network.
How the Internet Works

The InterNIC Registration Service assigns Internet addresses from the
following three classes:
 Class A - supports 16 million hosts on each of 127 networks
 Beginning bit pattern 0
 Class B - supports 65,000 hosts on each of 16,000 networks
 Beginning bit pattern 10 (10000000 10011100 00001110 00000111) translates
to 128.156.14.7
 Class C - supports 254 hosts on each of 2 million networks
 Beginning bit pattern 110

The current standard is the 32 bit IPv4 IP addressing system.

The number of unassigned Internet addresses is running out, so a
new classless scheme called CIDR (Classless Inter-Domain Routing)
is gradually replacing the system based on classes A, B, and C and is
tied to adoption of IPv6, short for Internet Protocol next generation.

IPv6 solves IPv4 address limitation by extending addressing from 32
to 128 bits.
How the Internet Works

You can test your connection to a site (server
computer) by using the ping command at the DOS
prompt followed by the URL of the site.

For example, you can ping Yahoo as follows:
C:\>ping www.yahoo.com

The result will indicate if there is a connection, how
long it took to reach the site round trip and what is
the IP address of the site server.
How the Internet Works
How the Internet Works
How the Internet Works

TRACEROUTE: a program primarily designed as a network debugging and
analysis tool and is a part of most operating systems. In Microsoft’s
Windows 9x, it’s name has been altered to TRACERT.

The purpose of this tool was to allow the tracing of the packets over the
Internet or any network using TCP/IP protocol. Observing how the program
functions helps to shed light on how packet switching works.

TRACERT uses a special number called the TTL (Time To Live) number
contained in a place at the beginning of each packet sent over the network.
The number is originally set to 255 and each time the packet is received by
a router along the way to its destination the number is decremented, usually
by 1. If the TTL reaches 0 before the packet reaches its destination and
error message is sent back to the original sender. The TTL number prevents
packets from circulating forever on the network.

You can use TRACERT, at the DOS prompt, to trace the route from your
computer to the Yahoo site server as follows:
C:\>TRACERT www.yahoo.com
How the Internet Works
How the Internet Works

You can find the IP address of your computer by going to:
 Start – Run then in the Open box type winipcfg and press Enter.
 The results will be similar to the box below for 98, Me, 2000:
Windows XP looks different
How the Internet Works

How IP addresses are normally assigned by an ISP
 Most IP addresses are assigned randomly and
automatically through a DHCP server.
 DHCP is short for Dynamic Host Configuration
Protocol, a protocol for assigning dynamic IP
addresses to devices on a network.
 With dynamic addressing, a device can have a
different IP address every time it connects to the
network.
 Dynamic addressing simplifies network
administration because the software keeps track of
IP addresses rather than requiring an administrator
to manage the task.
How the Internet Works
What is a domain name?
 Text version of IP address
IP address
Domain name
199.95.72.10
scsite.com
How the Internet Works
Domain Name System (or Service), an Internet service
that translates domain names into IP addresses.
 Because domain names are alphabetic, they're
easier to remember.
 The Internet is really based on IP addresses.
 Every time you use a domain name, therefore, a DNS
service must translate the name into the
corresponding IP address.
 For example, the domain name www.example.com
might translate to 198.105.232.4.
The World Wide Web
What is a URL? (Uniform Resource Locator)
 Unique address for Web page located on Web server
protocol
domain name
path
http://www.nationalgeographic.com/travel/index.html
The World Wide Web

A Uniform Resource Locator (URL) has 3 parts:

1) Type of connection (specifies protocol used at that
location):
Name
HTTP
FTP
SMTP
FILE
Gopher
WAIS
Telnet

Definition
HyperText Transport
Protocol
File Transfer Protocol
Email Protocol
Local file access
Name of Internet
access system
Wide area info. Service
Telephone Networking
Description
Mode through which WWW uses the Internet.
Used for transferring files between computers.
Used to send/create an email link.
Used to view HTML files.
Transfer type used by Gopher systems.
Tool for searching information databases.
Service for logging on to remote computers.
The majority of Web sites use http protocol, but you may see
some of the others while surfing the Web.
The World Wide Web
 2) The Internet address of the computer you are
trying to access:
 (Locates the specific computer on the Internet.)
Type of connection Top-level Domain
Path or Directory
http://www.eds.com/home/eds_home.html
Domain
Domain name: Identifies the
Internet address
Top-level Domain: Identifies
the type of organization
File name
Com
edu
gov
mil
net
org
Commercial site
Educational Institution
Government organization
Military organization
Networking organization
Nonprofit organization
The World Wide Web

ICANN (Internet Corporation for Assigned Names and Numbers), a
nonprofit group governing domain names, was created by the late Jon
Postel in the fall of 1998 in response to a policy statement issued by the
US Department of Commerce.




ICANN oversees the domain-name registration system's transition from
government hands to private hands and to coordinate the its
decentralization and integration into a global community.
The board of directors of ICANN has approved seven new top suffixes. The
new domain names are the first major additions since the system was
developed in the 1980s.
The new domain name suffixes will compete with the seven existing
domain name types, which include .net, .com, .org, .gov, .mil, and .edu.
The new suffixes appeared in use around mid-2001. It is similar to adding
area codes to the national phone system to accommodate growth.
The new suffixes can be grouped into three categories:




General purpose -- .biz, .info
Personal -- .name
Restricted use by community -- .aero, .coop, museum, and .pro.
Additionally, countries have two digit designations, such as, de Germany, fr
France, sg Singapore, ws Samoa and so on.
The World Wide Web

Domain name registration:

How can I determine whether the name I want is available?



Most domain name registering companies have a place for you to
enter the domain name you want and then search to see if it is
available. Thousands are registered each day.
Some domain name registration services are:

www.networksolutions.com

And many others.
www.domainmart.com
Who is InterNIC?


InterNIC is the only organization that maintains the database of
information related to a domain name under .com, .net, .org, and
.edu. Registrations, renewals, and modifications to any of the
information on the Whois database have to be processed through
them.
Under the current agreement with the U.S. Government, InterNIC,
Inc., as the InterNIC, provides domain name registration services in
.com, .net, .org, and .edu.
The World Wide Web

The usual cost to register a domain name is $35 per year.

Many registration companies have specials for less and also
offer Web page hosting and design services packages.

Some Web sites offer free hosting:


Yahoo and Geocities for example
Most ISPs offer some amount of free Web space (typically 6 to
10MB, but some up to 50MB) with your subscription to their
services. However, they may not allow the use of a domain
name, such as, www.something.com, etc.
The World Wide Web
 3) The path and name of the file:
 Identifies the location of the file and the name of the file
to be displayed on your screen.
 If the path (folder or subdirectory) or name of file have
been changed:

An error message will appear on your screen!

This error typically occurs when a page has been
moved, renamed, or deleted.

A way around this may be to gradually
shorten the URL until a valid Web page
appears.



http://www.example.com/website/document.html
http://www.example.com/website/
http://www.example.com/
The World Wide Web
What is the World Wide Web (WWW) ?
 A worldwide collection of electronic documents
 Also called the Web
 Each document is called a Web page
 Can contain text, graphics, sound, video, and links to other Web
pages
 A Web site is a collection of related Web pages
The World Wide Web

Internet needed improvements in user-friendliness. Three early
creations satisfied the need:




Gopher
Veronica
Archie
Gopher (University of Minnesota):




Land of the “Golden gophers.”
Introduced first improvement to accessing the Internet.
Menu-driven system gave access to databases of
information.
There were once over 5,000 gopher servers. Still used for
text based information.
The World Wide Web
Gopher menu for accessing the Internet
Internet Gopher Information Client v2.1.3
Home Gopher server: gopher.tc.umn.edu
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Information About Gopher/
Computer Information/
Discussion Groups/
Fun & Games/
Internet file server (ftp) sites/
Libraries/
News/
Other Gopher and Information Servers/
Phone books/
Search Gopher Titles at the University of Minnesota <?>
Search lots of places at the university of Minnesota <?>
University of Minnesota Campus Information/
Press ? For Help, q to Quit, u to go up a menu
The World Wide Web

World Wide Web (WWW or The Web)


A computer communications system that allows multimedia
information to be accessed and transmitted via the Internet. It is
an application that runs on the Internet.
The Web follows the Hypertext Transfer Protocol (HTTP).

Developed in 1989 by Tim Berners-Lee, a physicist at the
European high-energy physics laboratory in Switzerland.

Remember a protocol is a set of rules implemented in a
program.

Allows an individual computer to participate with other
computers through the Internet.

Converts text, visual and audio information into packets to
traverse the Internet.

Much better than the text only basis of Gopher.

Multimedia communication is more effective, easier to
understand by more people and conveys more information.
The World Wide Web
What is a Web browser?

Program
that allows
you to view
Web pages
• Netscape
• Internet
Explorer
• Opera
The browser reads
the HTML code and
builds the Web
page.
The World Wide Web

HTML - HyperText Markup Language, the authoring language used to
create documents on the World Wide Web.


HTML defines the structure and layout of a Web document by using a
variety of tags and attributes.
The correct structure for an HTML document starts with
<HTML>
<HEAD>
<TITLE>(enter here what document is about)</TITLE>
</HEAD>
<BODY>
and ends with
</BODY>
</HTML>.




All the information you'd like to include in your Web page fits in between
the <BODY> and </BODY> tags.
There are hundreds of other tags used to format and layout the
information in a Web page.
Tags are also used to specify hypertext links.
There are many HTML and Web authoring sites on the Internet, just do a
search.
The World Wide Web
An example of HTML
code and the page it
produces.
Next
p. 2.9
The World Wide Web
How do handheld computers and cellular telephones
access the Web?
 Must be Web-
enabled
 Uses a
microbrowser
that displays
Web pages that
contain mostly
text
Microbrowser for a
Web-enabled
cellular telephone
Microbrowser for a Webenabled handheld computer
The World Wide Web
What is a hyperlink?
 Text or graphic that
displays a related
Web page
 Also called a link
The World Wide Web
How can you identify a hyperlink (link) on a Web
page?
Mouse pointer
changes to a small
hand when you point
to a link
 Click the link to
display the associated
Web page
 Link can be a word,
mouse pointer changes to
phrase, or image
small hand

The World Wide Web
What is a search engine?
 Program used to find Web pages pertaining to a
specific topic
Search text
Spider
Word or phrase
entered in search
engine’s text box
Program used by
search engines to find
Web pages that
contain search text
Also called a
keyword
Also called a crawler
or bot
The World Wide Web
What are some
widely used
search engines?
The World Wide Web
What is a directory?
 Search tool
with
organized set
of topics and
subtopics
 Lets you find
information
by clicking
links rather
than entering
keywords
organized topics
from which you
select
The World Wide Web
What are graphic file formats?
The World Wide Web
What is a thumbnail?
 Small version of a
larger graphical
image
 Usually click
thumbnail on Web
page to display
full-sized image
full-sized
image
Web Publishing
How do you deploy a Web site?
Locate Web
server to store
your site
Upload, or
copy, site to
Web server
Other Internet Services
What is FTP?
 File Transfer
Protocol

Internet
standard that
allows you to
upload and
download files
with other
computers on
Internet
file
downlo
dialog
box
Other Internet Services
What is a newsgroup?
 Online area where users conduct written discussions
about particular subject
 User sends message to newsgroup
 Other users in newsgroup read and reply to message
Usenet
Entire collection of
Internet newsgroups
News server
Computer that stores
and distributes
newsgroup messages
Other Internet Services
What is a message board?
 Type of discussion group that does not require
newsreader
Also called a
discussion board
link to message about
financial issues
Other Internet Services
What is a chat?
 Real-time
conversation
that takes place
on a computer
 Chat room is
location on
server that
permits users
to discuss
topics of
interest
Other Internet Services
What is instant messaging (IM)?
 A real-time Internet
communications
service
Marianne’s message
immediately displays on
Jeff’s computer screen
because she is online
message sent from Marianne to
Jeff
Jeff’s response to Marianne
The Internet and World Wide Web
THE END