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Chapter 2: Technology Infrastructure: The Internet and the World Wide Web.

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Presentation on theme: "Chapter 2: Technology Infrastructure: The Internet and the World Wide Web."— Presentation transcript:

1 Chapter 2: Technology Infrastructure: The Internet and the World Wide Web

2 2 Objectives In this chapter, you will learn about: The origin, growth, and current structure of the Internet How packet-switched networks are combined to form the Internet How Internet protocols and Internet addressing work The history and use of markup languages on the Web, including SGML, HTML, and XML How HTML tags and links work on the World Wide Web The differences among internets, intranets, and extranets Options for connecting to the Internet, including cost and bandwidth factors Internet2 and the Semantic Web

3 3 The Internet and the World Wide Web Computer network –Any technology that allows people to connect computers to each other The Internet –A large system of interconnected computer networks spanning the globe World Wide Web –A subset of computers on the Internet

4 4 History of the Internet Wikipedia Internet HistoryInternet History Early 1960s –U.S. Department of Defense funded research to explore creating a worldwide network In 1969 –Defense Department researchers connected four computers into a network called ARPANET Throughout the 1970s and 1980s –Academic researchers connected to ARPANET and contributed to its technological developments

5 5 New Uses for the Internet 1972 – was born Mailing list – address that forwards any message received to any user who has subscribed to the list Usenet –Started by a group of students and programmers at Duke University and the University of North Carolina

6 6 Growth of the Internet In 1991, the NSF: –Eased restrictions on commercial Internet activity –Began implementing plans to privatize the Internet Network access points (NAPs) –Basis of the new structure of the Internet Network access providers –Sell Internet access rights directly to larger customers and indirectly to smaller firms and individuals through ISPs

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8 8 Emergence of the World Wide Web The Web –Software that runs on computers connected to the Internet Vannevar Bush speculated that engineers would eventually build a memory extension device (the Memex)Memex In the 1960s, Ted Nelson described a similar system called hypertext

9 9 Emergence of the World Wide Web Tim Berners-Lee developed code for a hypertext server programTim Berners-Lee Hypertext server: –Stores files written in the hypertext markup language –Lets other computers connect to it and read files Hypertext Markup Language (HTML) –Includes a set of codes (or tags) attached to text

10 10 Packet-Switched Networks Local area network (LAN) –Network of computers located close together Wide area networks (WANs) –Networks of computers connected over greater distances Circuit –Combination of telephone lines and closed switches that connect them to each other

11 11 Packet-Switched Networks (continued) Circuit switching –Centrally controlled, single-connection model Packets –Files and messages on a packet- switched network are broken down into small pieces, called packets –Travel from computer to computer along the interconnected networks until they reach their destinations

12 12 Routing Packets Routing computers –Computers that decide how best to forward packets Routing algorithms –Rules contained in programs on router computers that determine the best path on which to send packets –Programs apply their routing algorithms to information they have stored in routing tables

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14 14 Internet Protocols Protocol –Collection of rules for formatting, ordering, and error- checking data sent across a network Rules for message handling include: –Independent networks should not require any internal changes to be connected to the network –Packets that do not arrive at their destinations must be retransmitted from their source network –Router computers act as receive-and-forward devices –No global control exists over the network

15 15 TCP/IP TCP –Controls disassembly of a message or a file into packets before transmission over the Internet –Controls reassembly of packets into their original formats when they reach their destinations IP –Specifies addressing details for each packet

16 16 IP Addressing Internet Protocol version 4 (IPv4) –Uses a 32-bit number to identify computers connected to the Internet Base 2 (binary) number system –Used by computers to perform internal calculations Subnetting –Use of reserved private IP addresses within LANs and WANs to provide additional address space

17 17 IP Addressing (continued) Private IP addresses –Series of IP numbers not permitted on packets that travel on the Internet Network Address Translation (NAT) device –Used in subnetting to convert private IP addresses into normal IP addresses Internet Protocol version 6 (IPv6) –Protocol that will replace IPv4 –Uses a 128-bit number for addresses

18 18 Domain Names A domain name is a set of words assigned to a specific IP address Top-level domain (or TLD) –Rightmost part of a domain name Internet Corporation for Assigned Names and Numbers (ICANN) –Responsible for managing domain names and coordinating them with IP address registrars

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20 20 Web Page Request and Delivery Protocols Web client computers –Run software called Web client software or Web browser software Web server computers –Run software called Web server software The web uses a thin-client/server architecture –Combination of client computers running Web client software and server computers running Web server software

21 21 Web Page Request and Delivery Protocols Hypertext Transfer Protocol (HTTP) –Set of rules for delivering Web page files over the Internet Uniform Resource Locator (URL) –Combination of the protocol name and domain name –Allows a user to locate a resource (the Web page) on another computer (the Web server)

22 22 Electronic Mail Protocols Electronic mail ( ) –Must be formatted according to a common set of rules server –Computer devoted to handling client software –Used to read and send –Examples include Microsoft Outlook and Netscape Messenger

23 23 Electronic Mail Protocols Simple Mail Transfer Protocol (SMTP) –Specifies the format of a mail message Post Office Protocol (POP) –POP messages can tell the server to: Send mail to a users computer and delete it from the server Send mail to a users computer and not delete it Simply ask whether new mail has arrived –POP provides support for Multipurpose Internet Mail Extensions (MIME)

24 24 Markup Languages and the Web Text markup language –Specifies a set of tags that are inserted into text Standard Generalized Markup Language (SGML) –Older and more complex text markup language than HTML –A meta language World Wide Web Consortium (W3C) –Not-for-profit group that maintains standards for the Web

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26 26 Standard Generalized Markup Language Offers a system of marking up documents that is independent of any software application Nonproprietary and platform independent Offers user-defined tags Costly to set up and maintain

27 27 Hypertext Markup Language (HTML) Prevalent markup language used to create documents on the Web today HTML tags are interpreted by a Web browser and are used by it to format the display of the text HTML links can be structured as: –Linear hyperlink structures –Hierarchical hyperlink structures

28 28 Hypertext Markup Language (HTML)) The most common scripting languages include JavaScript, JScript, Perl, and VBScript Cascading Style Sheets (CSS) are sets of instructions that give Web developers more control over the format of displayed pages –Style sheet is: Usually stored in a separate file Referenced using the HTML style tag

29 29 Extensible Markup Language (XML) XML uses paired start and stop tags It includes data management capabilities that HTML cannot provide Differences between XML and HTML: –XML is not a markup language with defined tags –XML tags do not specify how text appears on a Web page

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31 31 Intranets and Extranets Intranet –Interconnected network that does not extend beyond the organization that created it Extranet –Intranet extended to include entities outside the boundaries of an organization –Connects companies with suppliers, business partners, or other authorized users

32 32 Public and Private Networks Public network –Any computer network or telecommunications network available to the public Private network –A private, leased-line connection between two companies that physically connects their intranets Leased line –Permanent telephone connection between two points

33 33 Virtual Private Network (VPN) VPN –An extranet that uses public networks and their protocols IP tunneling –Effectively creates a private passageway through the public Internet Encapsulation –Process used by VPN software

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35 35 Internet Connection Options Bandwidth –Amount of data that can travel through a communication line per unit of time Net bandwidth –Actual speed that information travels Symmetric connections –Provide the same bandwidth in both directions Asymmetric connections –Provide different bandwidths for each direction

36 36 Voice-Grade Telephone Connections POTS, or plain old telephone service –Uses existing telephone lines and an analog modem –Provides bandwidth between 28 and 56 Kbps Digital Subscriber Line (DSL) –Connection methods that do not use a modem Integrated Services Digital Network (ISDN) –Bandwidths between 128 Kbps and 256 Kbps

37 37 Broadband Connections Broadband connections operate at speeds of greater than 200 Kbps Asymmetric digital subscriber line (ADSL) –Transmission bandwidth is from 100 to 640 Kbps upstream and from 1.5 to 9 Mbps downstream Cable modems –Provide transmission speeds between 300 Kbps and 1 Mbps DSL –Private line with no competing traffic

38 38 Leased-Line Connections DS0 (digital signal zero) –Telephone line designed to carry one digital signal T1 line (also called a DS1) –Carries 24 DS0 lines and operates at Mbps Fractional T1 –Provides service speeds of 128 Kbps and upward in 128-Kbps increments T3 service (also called DS3) –Offers Mbps

39 39 Wireless Connections Bluetooth –Designed for personal use over short distances –Low-bandwidth technology, with speeds of up to 722 Kbps –Networks are called personal area networks (PANs) or piconets –Consumes very little power –Devices can discover each other and exchange information automatically

40 40 Wireless Ethernet (Wi-Fi) Wireless Ethernet (Wi-Fi or b) is the most common wireless connection technology for use on LANs Wireless access point (WAP) –Device that transmits network packets between Wi-Fi-equipped computers and other devices Has a potential bandwidth of 11 Mbps and a range of about 300 feet Devices are capable of roaming

41 41 Wireless Ethernet (Wi-Fi) (continued) a protocol –Capable of transmitting data at speeds up to 54 Mbps g protocol –Has 54 Mbps speed of a –Compatible with b devices n –Expected to offer speeds up to 320 Mbps

42 42 Fixed-Point Wireless One version of fixed-point wireless uses a system of repeaters to forward a radio signal from an ISP to customers Repeaters –Transmitter-receiver devices (transceivers) Mesh routing –Directly transmits Wi-Fi packets through hundreds, or even thousands, of short-range transceivers

43 43 Cellular Telephone Networks Third-generation (3G) cell phones –Combine the latest technologies available today Short message service (SMS) –Protocol used to send and receive short text messages Mobile commerce (m-commerce) –Describes the kinds of resources people might want to access using wireless devices

44 44 Internet2 and the Semantic Web Internet2 –Experimental test bed for new networking technologies –Includes bandwidths of 10 Gbps and more on parts of its network –Used by universities to conduct large collaborative research projects

45 45 Internet2 and the Semantic Web (continued) Semantic Web –Project by Tim Berners-Lee –If successful, it would result in words on Web pages being tagged (using XML) with their meanings Resource description framework (RDF) –Set of standards for XML syntax Ontology –Set of standards that defines relationships among RDF standards and specific XML tags

46 46 Summary TCP/IP –Protocol suite used to create and transport information packets across the Internet POP, SMTP, and IMAP –Protocols that help manage Languages derived from SGML –Hypertext Markup Language (HTML) –Extensible Markup Language (XML)

47 47 Summary (continued) Intranets –Private internal networks Extranet –Used when companies want to collaborate with suppliers, partners, or customers Internet2 –Experimental network built by a consortium of research universities and businesses


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