The Internet and the World Wide Web (WWW)

The Internet and the world wide web fuelled the growth of e-commerce

In this section of the course we will investigate the origin and structure of the Internet

What Is the Internet? The Internet is a large system of inter-connected

networks that span the globe 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 as well as downloading software

The Internet allows businesses to market and sell products and services

What Is the World Wide Web (WWW)? The world wide web (WWW) is a subset of

the computers on the Internet that connect in a certain way, making their content accessible to each other

The WWW includes an easy to use standard interface facilitating ease of use

Origins of the Internet 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)

Origins of the Internet (II) In 1969 the advanced research agency

(ARPA) used this network model to connect four computers

This network was called ARPANET During the 1970s and 80s the academic

community contributed to this network In the late 1980s this network became the

internet

Uses of the Internet In 1972 e-mail was created and used by the

military and research communities In 1979 the user’s news network (Usenet) was

created allowing users to post and read articles (newsgroups)

In 1989 the national science foundation (who funded the internet) allowed two commerce mail services, MCI mail and CompuServe

In 1990s people worldwide began using the Internet for many purposes including commerce

Internet Growth 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 added

The World Wide Web (WWW) The world wide web (or web) is software

that runs on machines connected to the Internet

The network traffic generated by the web is greater than e-mail, file transfers and other data traffic

The web is based on two concepts Hypertext and graphical user interface

Hypertext (II) In the 1960s, Ted Nelson described a

similar system He incorporated a page linking system called

hypertext In 1989, Tim Berners-Lee developed the

code for a hypertext server A hypertext server is a computer that stores

files written in hypertext markup language (HTML) and allow other computers to read it

HTML 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)

Graphical Interfaces for Hypertext Web browsers

Allow users to read HTML documents and navigate through them

Present an HTML document in a graphical user interface (GUI)

In 1993 the web browser Mosiac was developed, later Netscape Navigator and Internet Explorer were developed

Packet-switched Networks A LAN (local area network) is a network

of computers in close proximity A WAN (wide area network) network of

computers are connected over greater distances

Early WANs used leased lines Single path between caller and receiver

This is known as circuit switching

Internet Protocols (I) 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

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

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

IP Addresses IP addresses are assigned by:

American Registry for Internet Numbers (ARIN) North America, South America, the Caribbean and sub-

Saharan Africa

Reséaux IP Européens (RIPE) Europe, Middle East and the rest of Africa

Asia-Pacific Network Information Centre (APNIC) Asia-Pacific area

Domain Names (I) 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

Domain Names (II) 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

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

Hypertext Transfer Protocol The hypertext transfer protocol (HTTP)

was developed by Tim Berners-Lee in 1991

Client Web Server

Request sent to Web server

Response sent with files (one for eachWeb page, image, sound clip etc.)

Electronic Mail Protocols (I) Client server model used 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)

Electronic Mail Protocols (II) 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

Electronic Mail Protocols (III) 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

Electronic Mail Protocols (IV) 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

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

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

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

Internet Connection Options ISPs provide several ways to connect to the

Internet 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)

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

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

Broadband Connections (I) 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

Broadband Connections (II) 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

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)

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

(56Kbps) 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

Wireless Connections Satellite Bluetooth Wireless Ethernet (Wi-Fi) Fixed-Point Wireless Cellular Telephone Networks

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

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

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)

Wireless Ethernet (Wi-Fi) (802.11b) Most common

wireless on LANs Bandwidth 11Mbps at

300 feet A computer with a

Wi-Fi network can communicate with a wireless access point (WAP) to become a part of the network

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

Fixed Point Wireless Uses a system of

repeaters (transmitter-receiver 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

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

Cellular Telephone Networks (I) 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 resources

individuals might want to access (and pay for) using wireless devices