Download Electronic Commerce

Electronic Commerce
COMP3210
Session 2: Internetworking and the
WWW
Dr. Paul Walcott
Dr. Paul Walcott - Department of Computer Science, Mathematics and Physics, University of the West Indies,
Cave Hill Campus, Barbados, W.I.; email [email protected]; © 2005
Session Objectives

After completing this session you will
be able to:




Describe the Internet and discuss its
history
Describe the World Wide Web (WWW)
and write a simple HTML document
Describe different types of computer
networks
Discuss different methods of connecting
to the Internet
2
The Internet



What is the
Internet?
The history of the
Internet
The growth of the
Internet
3
What is the Internet1


The Internet is a large system of interconnected networks that span the
globe
Internet-ready computers and personal
digital assistants (palm and pocket
PCs) can access this network2
4
What is the Internet Cont’d

The Federal Networking Council (FNC)
defines the Internet more formally as
the global information system that3:

is logically linked together by a globally
unique address space based on the
Internet Protocol (IP) or its subsequent
extensions/follow-ons
5
What is the Internet Cont’d


is able to support communications using
the Transmission Control
Protocol/Internet Protocol (TCP/IP) suite
or its subsequent extensions/follow-ons,
and/or other IP-compatible protocols; and
provides, uses or makes accessible,
either publicly or privately, high level
services layered on the communications
and related infrastructure described
herein
6
What is the Internet Cont’d

The Internet allows:






communication by e-mail
the reading of on-line newspapers, academic
journals and books
the joining of discussion groups,
participation in simulations and games
downloading of software, electronic books and
music
businesses to market and sell products and
services (e-commerce)
7
The History of the Internet1


In the early 1960s the US department of
defense began investigating ways of
creating networks of computers that
coordinate and control nuclear weapons
This network was to withstand attack, so
that even if part of it was down it will
continue to function


This network was to have no central control
These new networks required multiple
channels to send information (leased lines
inadequate)
8
The History of the Internet Cont’d




In 1969 the advanced research agency
(ARPA) used this network model to connect
four computers
This network was called ARPANET
During the 1970s and 1980s the academic
community contributed to this network
In the late 1980s this network became the
Internet
9
Internet Growth1



In 1969 ARPANET (the Internet)
connected 4 computers
In 1990 the Internet connected
300,000
In 1995 the intranet was privatised


The structure was based on four network
access points (NAPs) operated by
different telecom companies in the US
As the Intranet grew, more NAPs were
10
Internet Growth Cont’d

The NAPs began selling Internet access
rights to large customers





Internet service provides (ISPs) sold on the
service to small businesses and individuals
Growth in Internet hosts rose from under 10
million in 1995 to over 180 million in 2004
Millions of people now use the Internet
Billions of dollars are exchanged from the
sales of products and services
Estimated number of Web sites is 40 million
and billions of web pages
11
The World Wide Web




www.ransen.com/Repligator/Spider.htm
What is the World
Wide Web?
What is hypertext?
Hypertext markup
language (HTML)
example
What types of Web
sites exist?
12
What is the World Wide Web

The World Wide Web (WWW) was an
Internet-based hypertext project that
allowed global information sharing2


It is software that runs on machines
connected to the WWW
The WWW is based on two concepts1:


Hypertext and
a graphical user interface (a Web
browser)
13
HyperText Markup Language



HTML is a language that includes a set
of tags attached to text
These tags describe the relationship
between text elements
A hypertext link (or hyperlink) points to
another location in the same or
another HTML document (that might
be stored on the same or another
computer)
14
HTML Example
<html>
<!-- An HTML document typically contains a head and a body -->
<head>
<title>Hypertext Markup Language (HTML) Example</title>
</head>
<!-- This is the body part of the document -->
<body bgcolor="#0000AA">
<font color="#FFFFFF">
<h1><u>Hypertext Markup Language</u></h1>
Hypertext Markup Language (HTML) allows users to:
<ol>
<li>format and display text
<li>display images
<li>and so much more …
</ol>
<img src="HTMLexample.jpg">
<a href="#top">Go to top of page</a>
</font>
</body>
</html>
15
Graphical Interface for Hypertext



A Web browser is a graphical user interface
used to read and navigate through files
written in HTML
In 1993 the first graphical web browser was
developed; called Mosiac
Popular web browsers include:



Internet Explorer
Netscape
Firefox
16
Hypertext Servers (Web Servers)1

There are several Web servers available
today, however the most popular are (April
2004 survey)4:



Apache HTTP Server (69.01%)
Microsoft Internet Information Server (IIS)
(23.26%)
Sun Java System Web Server (JSWS) (former
names are Sun One, iPlanet Enterprise Server
and Netscape Enterprise Server) (0.86%)
17
Apache (“A Patchy” Server)





Developed in 1994 by Rob McCool
The original core system has many patches
applied to it, and thus its name
Apache has dominated the Web since 1996
Available free
Runs on operating systems including
FreeBSD-UNIX, HP-UX, Linux, Microsoft
Windows, SCO-UNIX and Solaris
18
Microsoft Internet Information
Server (IIS)




Comes bundled with Microsoft Windows
Server operating system
IIS used on many corporate intranets
(Microsoft standard product)
Originally written to run on Windows NT and
Windows 2000; runs on Windows 2003
Server and Windows XP
Supports ASP, ActiveX Data objects and
SQL queries
19
Sun Java System Web Server




This is a descendant of the original
NCSA server
Cost US$1500-per-CPU licensing fee
Runs on HP-UX, Solaris and Windows
Is ODBC compatible (i.e. full access to
ODBC databases)
20
Web Site Types

There are numerous different types of Web
sites including:


Development sites: are used by companies to
evaluate web site designs. The initial investment
in these sites are small since they use existing
hardware (i.e. no special hardware is
purchased)
Intranets: these are corporate networks that
hold documents such as internal memos,
corporate handbooks, expense account
worksheets, budgets and newsletters
21
Web Site Types Cont’d


Extranets: which allow external entities, e.g.
suppliers and strategic partners to access a
subset of the information on the Intranet
Transaction-processing: These sites operate
24 hours a day, seven days a week and require
fast, reliable hardware and e-commerce
software

Web sites hosting B2B and B2C activities must have
spare capacity to support an increase in customer
volume.
22
Web Site Types Cont’d

Content-delivery: sites must be
available seven days a week, 24 hours a
day and require fast and precise search
engines to help visitors locate information
quickly

These sites deliver content such as news,
histories and other digital information.
23
Networking



What is a computer
network?
What are some of the
types of networks?
Characteristics of
networks




http://www-structure.llnl.gov/Xray/comp/network.gif


Network topology
Network protocols
Network architecture
Routers
Domain Names
Intranets, Extranets and
24
VPNs
What is a Network5

A network is a group of two or more
computer systems linked together
25
Types of Networks6

There are several types of computer
networks:

Local-area network (LANs)


Computers that are geographically close to
each other (in the same building)
Wide-area network (WANs)


Computers are farther apart than LANs;
typically connected by telephone lines or
radio waves
Provides a single path between caller and
receiver (circuit switching)
26
Types of Networks Cont’d

Campus-area network (CANs)


Metropolitan-area network (MANs)


These computers are within a limited
geographic area, e.g. a campus
These networks are designed for towns and
cities
Home-area network (HANs)

A network created in a person’s home
27
Types of Networks Cont’d


Both LANs and WANs are examples of
packet-switched networks
In packet-switched networks:



Messages are broken down into small pieces
called packets and are labeled electronically
with their origin, sequence and destination
addresses
Each packet may take a different path
The destination computer puts the packets back
together in the correct order
28
Characteristics of Networks5,6

A network is characterised by its:

Topology


Architecture


The geometric arrangement of the computer system
This refers to the two major type of networks, peer-topeer or client/server
Protocol

The set of rules and signals used to communicate (e.g.
Ethernet or IBM’s Token Ring)
29
Network Topologies6

Common network
topologies include:




Star topology
Ring topology
Bus topology
Other topologies
include the:


Mesh topology
Tree topology
http://www.webopedia.com/TERM/s/star_network.html
30
Network Topologies Cont’d

Network topologies are considered
either logical or physical



The physical lay out of the network is its
physical topology
The way signals are routed through a
network is the logical topology
Just because a network has a
particular physical topology does not
mean that its logical topology must be
the same
31
Network Topologies Cont’d

For example:


Twisted-pair Ethernet has a logical bus
topology on a physical star topology
layout
IBM’s token ring has a logical ring
topology on a physical star topology
32
Star Topology

In a Star network all nodes are
connected through a central hub


A node is a computer or device, e.g. a
printer; each node has a unique address
called the Data Link Control (DLC)
address or the Media Access Control
(MAC) address
The main advantage of the star
network is that a malfunctioning node
does not affect the rest of the network
33
Star Topology Cont’d

The main disadvantage of the star
network is that:



It requires more cabling than other
topologies (e.g. the ring network), and
If the hub goes down, the network no
longer functions
Standard twisted-pair Ethernet uses
the star topology
34
Ring Topology





Each node in a ring network is connected to two
other nodes to form a closed loop
Messages pass around the ring and each node
reads the message addressed to it
One advantage of a ring network is that it can span
larger distances than other networks (e.g. bus)
because each node regenerates the signal
One disadvantage is that malfunctioning nodes can
make other nodes inaccessible
IBM’s token ring uses a logical ring topology
35
Bus Topology





The nodes in a bus topology are connected to a
central cable call a bus or backbone
The bus has two end points
One advantage of the bus network is that if one
node goes down the network still functions
One disadvantage of the bus network is it can not
travel as long a distance as say a ring network due
to the diminishing signal strength
Ethernet 10Base-2 and 10Base-5 uses the bus
topology
36
Mesh Topology

In the mesh
topology many
redundant
connections exist
between nodes; in
a true mesh, each
node is connected
to every other node
http://www.webopedia.com/quick_ref/topologies.asp
37
Tree Topology

The tree topology
is a hybrid where
groups of starconfigured
networks are
connected to a
linear bus
backbone
http://www.webopedia.com/quick_ref/topologies.asp
38
Architecture6

The two main types
of architecture are


Peer-to-Peer
Client/Server
http://www.rebri.org.nz/images/builder-big.jpg
39
Peer-To-Peer (P2P) Networks


In a P2P network each node has
equivalent capabilities and
responsibilities
These networks are simpler than
Client/Server but do not offer the same
performance under heavy loads
40
Client/Server Networks




A network architecture where each node is
either a client or server
Client computers run applications, but rely
on servers for resources such as files and
printing capabilities
Servers are powerful computers that
manage files, printers or network traffic
This architecture is sometimes called the
two-tier architecture
41
Protocols


Protocols are agreed
formats for transmitting
data between devices6
The protocol
determines:




The error checking
required
Data compression
method used
The way the end of a
message is signaled T
The way the device
indicates that it has
received the message
42
Protocols Cont’d

A protocol is a collection of rules for:

Formatting, ordering and error checking
data that is sent across a network


e.g. The protocol might indicate when a
sending device has completed sending data
The ARPANET network used the
network control protocol (NCP)

It was based on an open architecture
which later became the Internet
43
Protocols Cont’d

Four key rules used by ARPANET were:




Independent networks (e.g. A LAN or WAN)
should not require internal changes in order to
be connected to the network
Packets that do not arrive at their destination
must be resent from their source network
Router computers act only as receiving and
forwarding devices; They do not retain
information about the packets they handle
No global control of the network exist
44
Internet Protocols

There are many protocols used by the
Internet and the WWW, including




TCP/IP
HTTP
FTP
Electronic mail protocols


IMAP
POP
45
TCP/IP

The Internet uses two main protocols
(developed by Vicent Cerf and Robert Kahn)

Transmission control protocol (TCP)



Controls disassembly of message into packets at the
origin
Reassembles at the destination
Internet protocol (IP)

Specifies the addressing details for each packet

Each packet is labeled with its origin and destination
46
Internet Protocol version 4
(IPv4)

Uses a 32 bit number to identify each
computer


Called the IP address (4 billion
addresses)
IP addresses uses the dotted decimal
notation, e.g. 0.0.0.0 or 255.255.255.255
47
Internet Protocol version 6
(IPv6)


Set to replace version 4
Changes the format of the packets


Removes unused fields
Uses 128 bit number (2^128
addresses)

Eight groups of 16 bits


e.g.
CD18:0000:0000:AF23:0000:FF9E:61B2:884
D
To simplify zeroes may be removed
48

CD18:::AF23::FF9E:61B2:884D
Internet Addresses
Internet addresses are represented in several ways,
but all the formats are translated to a 32-bit number
called an IP address; a function of Internet Protocol (IP)
The increased demand for IP addresses will soon
make 32-bit addresses too small, and they will be
replaced with 128-bit addresses (IP v6.0) in the near future.
How does increasing the number of bits in the address help
with increasing demand?
49
Dotted Quads
•
IP numbers appear as a series of up to 4 separate
numbers delineated by a period.
•
Examples:
students.depaul.edu: 140.192.1.100
condor.depaul.edu: 140.192.1.6
facweb.cs.depaul.edu: 140.192.33.6
•
Each of the four numbers can range from 0 to 255, so
the possible IP addresses range from
0.0.0.0 to 255.255.255.255
50
Elements of Internet Addressing
51
Domain Names
• Since IP numbers can be difficult for humans to
remember, domain names are associated with
each IP address.
• Examples:
students.depaul.edu: 140.192.1.100
facweb.cs.depaul.edu: 140.192.33.6
• A domain name server is responsible for the mapping
between domain names and IP addresses.
• Domain names and IP addresses are registered
separately. Registering domain name doesn’t imply
getting an IP address. IP address is from hosting
service.
52
Uniform Resource Locator
• People on the Web use a naming convention called the
uniform resource locator (URL).
• A URL consists of at least two and as many as
four parts.
• A simple two part URL contains the protocol
used to access the resource followed by the
location of the resource.
Example: http://www.cs.depaul.edu/
• A more complex URL may have a file name
and a path where the file can be found.
53
A URL deconstructed
http://www.daschmelzer.com/ect250/hw/h1/h1.htm
hypertext
transfer
protocol
domain
path that indicates
the location of the
document in the
host’s file system
document
name
This is considered a fully specified URL
54
Anatomy of an eMail Address
dschmelzer @ cti . depaul . edu
Handle
Host/Server
Domain
Domain
Type
Others:
• students
• hawk
• condor
55
Shortened URL




Simply by typing www.cs.depaul.edu into
browser allows http to locate specific file
Web servers are set to “default” to specific
file names when full URL (or filename) not
given.
index.htm (.html, .asp, .jsp, etc) and
default.htm (etc……) are examples.
Name the template file in HW1: index.htm
56
Domain types

.com


U.S. government agencies

U.S. military
Network computers
.org

Nonprofit organizations
and foundations
Museums
.name


Cooperatives
.museum


Air transport industry
.coop


information providers
.aero

.net



business firms
.info

.mil



.gov


Educational institutions
.biz

.edu


Commercial organizations
or businesses

Individuals
.pro

Professionals
57
Hypertext Transfer Protocol (HTTP)7



The hypertext transfer protocol (HTTP) was
developed by Tim Berners-Lee in 1991
HTTP was designed to transfer pages
between machines
The client (or Web browser) makes a
request for a given page and the Server is
responsible for finding it and returning it to
the client
58
Hypertext Transfer Protocol (HTTP)


The browser connects and requests a page from
the server
The server reads the page from the file system,
sends it to the client and terminated the connection
Request sent to Web server
Web Server
Client
Response sent with files (one for each
Web page, image, sound clip etc.)
59
File Transfer Protocol (FTP)2

FTP is a protocol that allows a user to:





list files at a remote site
Transfer files between local and remote computers
Using FTP you can not run applications on a remote
site
Also you can only look at the names of the files on
the remote computer; rather than being able to read
them
FTP is still used today; e.g. to transfer large files
between computers, or to upload Web sites
60
Electronic Mail Protocols


Electronic mail uses the client/server
model
The organisation has an email server
devoted to handling email


Stores and forwards email messages
Individuals uses email client software
to read and send email (e.g. Microsoft
Outlook, or Netscape Messenger)
61
Electronic Mail Protocols
Cont’d

Simple Mail Transfer Protocol (SMTP)


Specifies format of mail messages
Post Office Protocol (POP)

tells the email server to:



Send mail to the user’s computer and delete
it from the server
Send mail to the user’s computer and do not
delete it from the server
Ask whether new mail has arrived
62
Electronic Mail Protocols
Cont’d

Interactive Mail Access Protocol
(IMAP)

Newer than POP, provides similar
functions with additional features



e.g. can send specific messages to the client
rather than all the messages
A user can view email message headers and
the sender’s name before downloading the
entire message
Allows users to delete and search
mailboxes held on the email server
63
Electronic Mail Protocols
Cont’d

The disadvantages of POP


You can only access messages from one
PC
The disadvantage of IMAP

Since email is stored on the email server,
there is a need for more and more
expensive (high speed) storage space
64
Terminal Emulation




Telnet is a terminal emulation program for
TCP/IP networks
The telnet program runs on a local machine
and allows connection to a remote machine
Commands entered through the telnet
program will be executed on the Server; this
gives the user the ability to control the
Server
To log into the Server a valid username and
password is required
65
Routers




Computers that decide how best to forward
on a packet to its destination is called a
routing computer
The Internet uses routers to isolate each
LAN or WAN
Each WAN or LAN can use their own
protocol for packet traffic within the LAN or
WAN
The actual programs which contains the
routing rules are called routing algorithms
66
Routers Cont’d

These programs apply their routing
algorithms to information they have
stored in routing tables



This information includes lists of
connections that lead to particular groups
of other routers
Which connections to use first
Rules for handling instances of heavy
packet traffic and network congestion
67
Routers Cont’d


When a company connects to the Internet it
must connect at least one router to routers
owned by other companies that make up the
Internet
The Internet backbone are a set of routers
that handle packet traffic along the Internet’s
main connecting points


These are very large computers that can handle
more than 50 million packets per second
A router connected to the Internet always has
more than one path to direct packets
68
Domain Names


To make Internet addresses easier to
remember an alternative, domain names,
was provided which used words
Domain names

May have two or more groups separated by a
period, e.g. www.cavehill.uwi.edu




Edu – an education institution
Cavehill and uwi – the computer’s name
www – part of the world wide web
Not all computers follow this convention, e.g
games.yahoo.com
69
Domain Names Cont’d

The rightmost part of the domain name is called the
top-level domain (or TLD), e.g. .edu, or .com


also Country domains e.g. .bb
In 2000 seven new general TLDs were added:






.aero – air transport industry
.biz – businesses
.coop – cooperatives
.museum – museums
.name – individuals
.pro - professionals
70
Uniform Resource Locator

The combination of the domain name
and the protocol name is called the
uniform resource locator (URL)

E.g. http://www.yahoo.com


http is the protocol
www.yahoo.com is the domain name
71
Intranets and Extranets


An Intranet is an interconnected network
(internet) that does not extend beyond the
organisation that created it
An extranet is an intranet that has extended
to include specific entities outside of the
organisation, e.g. business partners,
customers or suppliers

Extranets can replace faxes, telephones, email
and overnight carriers, at a lower cost
72
Intranets





Low cost distribution of internal corporate
information
Based on client server model
Intranets use Web browsers, internet-based
protocols including TCP/IP, FTP, Telnet, HTML and
HTTP
Distributing paper is often more expensive
Intranets can also be used to provide software
updates and patches, which update users
computers automatically – using scripts
73
Extranet



Networks that connect companies with
suppliers, business partners and authorised
users
Each user has access to the databases,
files and other information stored on
computers connected to the extranet
Fedex changed from an Intranet to Extranet
for package tracking on their Web site
74
Public and Private Networks


A public network is any network available to the
public, e.g. Internet
A private network is a private (e.g leased) line
between two computers




Leased line is a permanent connection between two
points
line is always active (unlike telephone connection)
The advantage is security (only the two parties can
connect to the network)
The disadvantage is the cost due to the scaling problem:
to connect 5 pairs, 5 lines are required
75
Virtual Private Networks


A VPN is an extranet that uses public
networks and their protocols to send
sensitive information using IP
tunneling
IP tunneling creates a private
passageway through the public
Internet that provides secure
transmissions
76
Virtual Private Networks
Cont’d





VPN software encrypts the package content and
places it into another packet (encapsulation)
The outer packet is called an IP wrapper
The receiving computer decrypts it using the (VPN
software)
The connection is ‘virtual’ since it is only temporary,
it is created when information needs to be
transmitted
A VPN is an extranet, but not every extranet is a
VPN
77
Connecting to the Internet1

What are some of
the ways of
connecting to the
Internet?
http://www.co.delaware.ny.us/links.htm
78
Internet Connection Options

Internet service providers (ISPs) provide
several ways to connect to the Internet,
including:





Voice grade telephone lines
Broadband connections
Leased lines
Wireless
The major distinguishing factor is bandwidth
(the amount of data that can be transferred
per unit of time)
79
Bandwidth and Connections


Symmetric connection: provides the same
bandwidth in both directions
Asymmetric connections: provide different
bandwidths for either direction


Upstream bandwidth (upload bandwidth): the
amount of information that can travel from the
user to the Internet in a given amount of time
Downstream bandwidth (download or downlink
bandwidth): the amount of information that can
be transferred from the Internet to the user in an
amount of time
80
Voice-grade Telephone Connections

Most common way to connect to ISP


Modem (analog) connected to telephone lines
POTS (plain old telephone service)


28 to 56Kbps
Digital subscriber line (DSL) protocol


Does not use a modem
Uses a piece of network equipment similar to a
network switch

Integrated services digital network (ISDN) first used
DSL protocol suite in 1984

More expensive, but offers bandwidth of 128Kbps –
256Kbps
81
Broadband Connections
Cont’d


Connections that operate at speeds higher
than 200Kbps are considered broadband
One of the latest is asymmetric digital
subscriber line (ADSL)


Bandwidths from 100-640Kbps upstream and
from 1.5 to 9 Mbps downstream
For businesses a high-speed DSL (HDSL) is
available

768Kbps of symmetric bandwidth
82
Broadband Connections
Cont’d

Cable modems (connected to the
same broadband coaxial cable that
serves a television)

Upstream bandwidth of 300Kbps to 1
Mbps and downstream bandwidth of
10Mbps
83
DSL v Cable



DSL is a private line with no competing
traffic
Cable connections bandwidth change with
the user load (number of subscribers using
the service)
Problems

Web users in rural areas often do not have cable
access and have limited telephone access (low
cost voice-grade lines, rather than data-grade
lines) thus bandwidth is limited (<14Kbps)
84
Leased-Line Connections


Large firms with a large amounts of Internet traffic
can lease lines from telecommunication carriers
Various technologies are used; classified by the
amount of telephone lines they include:




DS0 (digital signal zero) carries one digital signal
(64Kbps)
T1 (or DS1) carries 24 DS0 lines (1.544Mbps)
Fractional T1 (128Kbps and upwards)
T3 (or DS3) carries 30 T1 lines (44.736Mbps)

Connections more expensive than POTS, ISDN and DSL
85
Wireless Connections





Satellite
Bluetooth
Wireless Ethernet (Wi-Fi)
Fixed-Point Wireless
Cellular Telephone Networks
86
Satellite

Satellite microwave
transmissions




Customer placed
receiving dish in
yard
Download
bandwidth of
around 500 kbps
Maximum upload
bandwidth of
150kbps
Self installation
makes cost lower
87
http://www.ccpo.odu.edu/~arnoldo/ocean405/satellite.gif
Bluetooth




One of the first
wireless protocols
Operates reliably over
35 feet and can be
part of up to 10
networks of eight
devices each
(personal area
networks, or PANs)
Bandwidth of 722kbps
Good for wireless
printing
http://www.bakercountyhealth.org/services/dental/blue-tooth.jpg
88
Bluetooth Advantages


Bluetooth technology consumes very
little power
Bluetooth devices can discover each
other and exchange information
automatically (e.g. a user can print to a
printer on a network without logging
on)
89
Wireless Ethernet (Wi-Fi) (802.11b)



Most common wireless
on LANs
Bandwidth 11Mbps at
300 feet
A computer with a WiFi network can
communicate with a
wireless access point
(WAP) to become a
part of the network
90
http://www.homenethelp.com/web/diagram/images/shareing-soft-wireless.gif
Wireless Ethernet Advantages


Wi-Fi devices can roam, i.e. shift from
one WAP to another without user
intervention
Increasingly WAPs are becoming
available in public places, e.g. airports
91
Wireless Ethernet
Developments

In 2002 an improved version of Wi-Fi, called
802.11a was introduced




The 802.11a protocol is capable of transmitting
at speeds up to 54Mbps
802.11a is not compatible with 802.11b
Later in 2002, the 802.11g protocol was
introduced which is compatible with 802.11b
devices and has speeds of 54Mbps
In 2004-2005, 802.11n expected (320Mbps)
92
Fixed Point Wireless


Uses a system of
repeaters (transmitterreceiver devices) to
forward a radio signal
from the ISP to
customers
Users’ antennas are
connected to a device
that converts radio
signals to Wi-Fi
packets which are sent
to their computers
http://www.erinc.com/apps_wireless/images/fixed_wireless2.gif
93
Cellular Telephone Networks



In 2003, about 500
million mobile (cell)
phones worldwide
Originally slow data
communication (10
kbps – 384kbps)
Third generation
cell phones

Up to 2 Mbps
http://www.mtco.com/graphics/cellularpic.jpg
94
Cellular Telephone Networks Cont’d



Cell phones send and receive messages
using the short message service (SMS)
protocol
Some cell phones include Web browser
which provide web access, email, short
message service
Companies also sell Internet access through
their cellular networks


Fixed fee plus charge for amount of data
transferred
Business potential of mobile commerce

Companies are identifying the kinds of
95
References
[1] Schneider, Gary, P., “Electronic Commerce: The second wave”, Thomson Course
Technology, Fifth Annual Edition, 2004
[2] Zhao, Jensen J., “Web design and development for e-business”, Prentice Hall,
2003
[3] Federal Networking Council, “FNC Resolution: Definition of the Internet”, 1995.
Online document available at http://www.itrd.gov/fnc/Internet_res.html
[4] NetCraft, “April 2004 Web Server Survey”, 2004. Online document available at
http://news.netcraft.com/archives/2004/04/01/april_2004_web_server_survey.ht
ml
[5] Furdyk, Michael, “Ultimate Guide to Networking: Part One”, 1999. Online
document available at
http://www.hardwarecentral.com/hardwarecentral/print/158/
[6] Webopedia, “Network”, 2004. Online document available at
http://networking.webopedia.com/TERM/N/network.html
[7] Berlin, Dan, et al., “CGI Programming Unleased”, Sams.net Publishing, 1996, pp.
101-102
96