Learning Center
Plans & pricing Sign in
Sign Out



									Electronic Commerce

   Dr. Paul Walcott
   Part I
       The Internet and the World Wide Web (WWW)
   Part II
       Internet Protocols and addressing
       Packet-Switched Networks
   Part III
       Intranets and Extranets
       Internet Connection Options
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
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
   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
   This network was to withstand attack, so that
    even if part of it was down it will continue to
       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
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
   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
Internet Growth
   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 change hands from the sales of
    products and services
   Estimated number of Web sites is 40 million and
    billions of web pages
The World Wide Web (WWW)
   The world wide web (or web) is software
    that runs on machines connected to the
   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
   In 1945, Vannevar Bush wrote an article in
    Atlantic Monthly about a system, called
    Memex, that would store all a person’s
    books, records, letters and research results
    on microfilm
   Microfilm and indexes would then be used
    to quickly access this information
Hypertext (II)
   In the 1960s, Ted Nelson described a
    similar system
       He incorporated a page linking system called
   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 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
   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
   Early WANs used leased lines
       Single path between caller and receiver
           This is known as circuit switching
Packet-switched Networks (II)
   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
Routing Packets
   Computers that decide how best to forward
    on a packet to its destination is called a
    routing computer
   The actual programs which contains the
    rules are called routing algorithms
   These programs apply their routing
    algorithms to information they have stored
    in routing tables
Routing Packets (II)
       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
   The network devices that move packets
    from one part of a network to another are
    called routers
Routing Packets (III)
   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
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
Internet Protocols (II)
   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
   The Internet uses routers to isolate each
    LAN or WAN (mentioned earlier)
   Each WAN or LAN can use their own
    protocol for packet traffic within the LAN
    or WAN
   The router moves the packets onto the
    Internet in its standard format
   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
       Called the IP address (4 billion addresses)
       IP addresses uses the dotted decimal
        notation, e.g. or
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.
         To simplify zeroes may be removed
               CD18:::AF23::FF9E:61B2:884D
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.
           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
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 is the protocol
         is the domain name
   Hypertext Transfer Protocol
        The hypertext transfer protocol (HTTP)
         was developed by Tim Berners-Lee in

               Request sent to Web server

Client                                                Web Server

             Response sent with files (one for each
              Web 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
       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
   Low cost distribution of internal corporate
   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
   Networks that connect companies with
    suppliers, business partners and authorised
   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
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
       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
Virtual Private Networks (I)
   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
Virtual Private Networks (II)
   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
Internet Connection Options
   ISPs provide several ways to connect to the
       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
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
   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
       768Kbps of symmetric bandwidth
Broadband Connections (II)
   Cable modems (connected to the same
    broadband coaxial cable that serves a
       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
   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
   Various technologies are used; classified by the
    amount of telephone lines they include:
       DS0 (digital signal zero) carries one digital signal
       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 microwave
       Customer placed
        receiving dish in yard
       Download bandwidth
        of around 500 kbps
       Maximum upload
        bandwidth of 150kbps
       Self installation
        makes cost lower
   One of the first wireless
   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
Bluetooth Advantages
   Bluetooth technology consumes very little
   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)
   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
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)
Fixed Point Wireless
   Uses a system of
    repeaters (transmitter-
    receiver devices) to
    forward a radio signal
    from the ISP to
   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
       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
   A computer network is any technology
    that allows more than one computer to be
    connected together

To top