1. 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

2. 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

3. 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

4. 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)

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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)

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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.eduwww.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

18. 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

19. 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.comhttp://www.yahoo.com http is the protocol www.yahoo.com is the domain name www.yahoo.com

20. 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 each Web page, image, sound clip etc.)

21. 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)

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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)

29. 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

30. 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

31. 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

32. 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

33. 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)

34. 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

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

36. 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

37. 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

38. 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)

39. 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

40. 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

41. 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

42. 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

43. 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