电子商务概论_PPT_ch0218202.pptx

《电子商务概论_PPT_ch0218202.pptx》由会员分享，可在线阅读，更多相关《电子商务概论_PPT_ch0218202.pptx（87页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、ELEVENTH EDITION ELECTRONIC COMMERCEGARY P.SCHNEIDERTechnology Infrastructure:The Internet and the World Wide WebChapter 2 Cengage Learning 2015Learning ObjectivesIn this chapter,you will learn:About the origin,growth,and current structure of the Internet How packet-switched networks are combined to

2、 form the Internet How Internet,e-mail,and Web protocols work About Internet addressing and how Web domain names are constructed Cengage Learning 2015 2 2Learning Objectives(contd.)About the history and use of markup languages on the Web How HTML tags and links work About technologies people and bus

3、inesses use to connect to the Internet About Internet2 and the Semantic Web Cengage Learning 2015 3 3Introduction A growing number of Internet users are using smartphone or tablet Smartphones are typically only the access method in developing countries History of Internet-capable mobile phones First

4、 introduced in late-1990s Slow,unreliable service,no keyboards 2001:Treo,Blackberry introduced 2009:All major phone manufacturers had products 2011-2013:Lower price phones targeted developing markets Cengage Learning 2015 4The Internet and the World Wide Web Computer network Technology allowing peop

5、le to connect computers Internet(capital“I)Interconnected global computer networks internet(small“i”)Group of interconnected computer networks Basic technology structure Supports networks,the Internet,and e-commerce Cengage Learning 2015 5 5The Internet and the World Wide Web(contd.)World Wide Web(W

6、eb)Subset of Internet computers Includes easy-to-use interfaces Cengage Learning 2015 6 6Origins of the Internet Early 1960s Defense Department nuclear attack concerns Powerful computers(large mainframes)Leased telephone company lines Single connection Single connection risk solution Communicate usi

7、ng multiple channels(packets)1969 Advanced Research Projects Agency(ARPA)Packet network connected four computers ARPANET:earliest network(became the Internet)Academic research use(1970s and 1980s)Cengage Learning 2015 7New Uses for the Internet Defense Department network:the original goal To control

8、 weapons systems;transfer research files 1970s:other uses E-mail(1972)Networking technology Remote file transfer and computer access Mailing lists 1979:Usenet(Users News Network)Read and post articles Newsgroups(topic areas)Cengage Learning 2015 8New Uses for the Internet(contd.)Limited Internet use

9、 Research and academic communities 1979 1989 Network applications improved and tested Defense Departments networking software Gained wider academic and research institution use Common communications network benefit recognized Security problems recognized 1980s:personal computer use explosion Academi

10、c and research networks merged Cengage Learning 2015 9Commercial Use of the Internet National Science Foundation(NSF)Provided funding Prohibited commercial network traffic Businesses turned to commercial e-mail providers Larger firms built networks(leased telephone lines)1989:NSF permitted two comme

11、rcial e-mail services(MCI Mail and CompuServe)Commercial enterprises could send e-mail Research,education communities sent e-mail directly to MCI Mail and CompuServe Cengage Learning 2015 10Growth of the Internet 1991 Further easing of commercial Internet activity restrictions 1995:privatization of

12、the Internet Operations turned over to privately owned companies Internet based on four network access points(NAPs)Network access providers Sell Internet access rights directly to larger customers Use Internet service providers(ISPs)Sell to smaller firms and individuals Cengage Learning 2015 11Growt

13、h of the Internet(contd.)Internet hosts:directly connected computers Internet growth One of the most significant technological and social accomplishments of last millennium Nearly every country involved Used by millions of people Billions of dollars change hands yearly Cengage Learning 2015 12 Cenga

14、ge Learning 2015 13FIGURE 2-1 Growth of the Internet Cengage Learning 2015The Internet of Things Devices can be connected to the Internet Controlled remotely Examples:sensors,switches,optical scanners The Internet of things Term used for these connected devices Estimated size is nine billion Project

15、ed to reach 35 billion by 2020 Cengage Learning 2015 14Packet-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 connecting them

16、 to each other Circuit switching Centrally controlled,single-connection model Single electrical path between caller and receiver Cengage Learning 2015 15Packet-Switched Networks(contd.)Circuit switching(contd.)Works well for telephone calls Does not work as well for:Sending data across large WAN and

17、 interconnected network(Internet)Circuit-switched network problem Connected circuit failure Causes interrupted connection and data loss Solution Packet switching:move data between two points Cengage Learning 2015 16Packet-Switched Networks(contd.)Packet-switched network Packets Small pieces labeled

18、electronically(origin,sequence,and destination address)Travel along interconnected networks Can take different paths May arrive out of order Destination computer Collects packets Reassembles original file or e-mail message Cengage Learning 2015 17Routing Packets Routing computers Decide how best to

19、forward each packet Also known as routers,gateway computers,border routers Gateway from LAN or WAN to Internet Border between organization and the Internet Routing algorithms Programs on routing computers Determine best path for packet Cengage Learning 2015 18Routing Packets(contd.)Routing algorithm

20、s applied to routing table(configuration table)information Routing table(configuration table)information Includes lists of connections Provides rules for:Specifying connection to use first Handling heavy packet traffic and network congestion Variety of rules and standards for creating packets Hubs,s

21、witches,and bridges Devices that move packets Cengage Learning 2015 19Routing Packets(contd.)Routers connect networks Translate packets into standard format Internet backbone Routers and telecommunication lines between Internets main collecting points Cengage Learning 2015 20 Cengage Learning 2015 2

22、1FIGURE 2-2 Router-based architecture of the Internet Cengage Learning 2015Public and Private Networks Public network Public availability Private network Private,leased-line connection Physically connects intranets to one another Leased line Permanent telephone connection between two points Advantag

23、e:security Drawback:cost Scaling problem:adding companies Cengage Learning 2015 22Virtual Private Network(VPN)Connection via public networks and protocols Uses IP tunneling(encapsulation)system Private passageway through public Internet Secure transmission Encapsulation Encrypts packet content;place

24、s inside another packet IP wrapper:outer packet VPN software installed on both computers“Virtual”since connection seems permanent Actually a temporary connection Cengage Learning 2015 23Intranets and Extranets Intranet An Internet within the boundaries of the organization Interconnected private netw

25、orks Extranet An Internet that extends beyond the organization and incorporates networks of outside entities Technologies(public networks,private networks,or VPNs)Independent of organizational boundaries Cengage Learning 2015 24Internet Protocols Protocol:collection of network data rules Includes tr

26、ansmission rules Computers must use same protocol ARPANET:Network Control Protocol(NCP)Proprietary architecture(closed architecture)Manufacturer creates own protocol Open architecture(Internet core)Uses common protocol Four key message-handling rules Contributed to the Internets success Cengage Lear

27、ning 2015 25TCP/IP Refers to the two pervasive protocols used today Transmission Control Protocol(TCP)Controls message or file disassembly into packets before Internet transmission Controls packet reassembly into original formats at destinations Internet Protocol(IP)Specifies addressing details for

28、each packet Labels packet with origination and destination addresses Cengage Learning 2015 26IP Addressing Internet Protocol version 4(IPv4)Used since 1981 IP address 32-bit number identifying computers Base 2(binary)number system Computers use for internal calculations Digit:0 or a 1(on or off cond

29、ition)Four billion different addresses(232=4,294,967,296)Router breaks message into packets Contains source and destination IP address Cengage Learning 2015 27IP Addressing(contd.)Dotted decimal notation Four numbers separated by periods IP addresses range:0.0.0.0 to 255.255.255.255 Byte(8-bit numbe

30、r)Called an octet(networking applications)Binary values:00000000 to 11111111 Decimal equivalents:0 to 255 Three organizations assign IP addresses ARIN Whois server Returns IP address list owned by an organization Cengage Learning 2015 28IP Addressing(contd.)New devices creating high demand for IP ad

31、dresses Subnetting Use reserved private IP LAN(WAN)addresses Provides additional address space Private IP addresses IP numbers not permitted on Internet packets Network Address Translation(NAT)device Converts private IP addresses into normal IP addresses Cengage Learning 2015 29IP Addressing(contd.)

32、Internet Protocol version 6(IPv6)Replaces IPv4 Addresses predicted to be exhausted in 2015 IPv4 and IPv6 not directly compatible IPv6 major advantages Uses 128-bit number for addresses Number of available addresses:34 followed by 37 zeros More complex notation system Cengage Learning 2015 30Electron

33、ic Mail Protocols Electronic mail(e-mail)Formatted according to common set of rules Client/server structure E-mail server Computer devoted to e-mail handling Stores,forwards e-mail messages E-mail client software Reads and sends e-mail Communicates with e-mail server software Standardization and rul

34、es are essential Cengage Learning 2015 31Electronic Mail Protocols(contd.)Two common protocols Simple Mail Transfer Protocol(SMTP)Specifies mail message format Describes mail administration e-mail server Describes mail transmission on the Internet Post Office Protocol(POP)Sends mail to users compute

35、r;deletes from server Sends mail to users computer;does not delete Asks if new mail arrived Cengage Learning 2015 32Electronic Mail Protocols(contd.)Multipurpose Internet Mail Extensions(MIME)Set of rules for handling binary files Interactive Mail Access Protocol(IMAP)Same basic POP functions Additi

36、onal features that support user access to email from any computer One disadvantage:storage of e-mail messages on e-mail server Cengage Learning 2015 33Web Page Request and Delivery Protocols Web client computers Web client software(Web browser software)Sends Web page file requests to other computers

37、(Web servers)Web server computer Web server software Receives requests from many different Web clients Client/server architecture Combination:client computers,server computers Cengage Learning 2015 34Web Page Request and Delivery Protocols(contd.)Hypertext Transfer Protocol(HTTP)Internet Web page fi

38、le delivery rules Web page request using Web browser User types protocol name Followed by“/:”characters before the domain name Uniform Resource Locator(URL)Combination:protocol name,domain name Locates resources(Web page)on another computer(Web server)Cengage Learning 2015 35Emergence of the World W

39、ide Web Web Software running on Internet-connected computers Generates network traffic Web software:largest single traffic category Outpaces:e-mail,file transfers,and other data transmission traffic Web resulted from new ways of thinking about information storage and retrieval Key technological Web

40、elements Hypertext Graphical user interfaces Cengage Learning 2015 36The Development of Hypertext 1945:Vannevar Bush:The Atlantic Monthly article Visionary ideas:future technology uses(Memex)1960s:Ted Nelson described hypertext Page-linking system Douglas Engelbart:experimental hypertext system 1987

41、:Nelson published Literary Machines Outlined project Xanadu global system Online hypertext publishing and commerce Cengage Learning 2015 37The Development of Hypertext(contd.)1989:Tim Berners-Lee Proposed hypertext development project Provided data-sharing functionality Developed hypertext server pr

42、ogram code Hypertext server Stores Hypertext Markup Language(HTML)files Computers connect and read files Web servers(today)Hypertext servers used on the Web Cengage Learning 2015 38The Development of Hypertext(contd.)HTML Set of codes(tags)attached to text Describes relationships among text elements

43、 Hypertext link(hyperlink)Points to another location Same or another HTML document Cengage Learning 2015 39Graphical Interfaces for Hypertext Web browser Software,e.g.,Mozilla Firefox or MS Internet Explorer Users read(browse)HTML documents Move from one HTML document to another Text formatted with

44、hypertext link tags in file Graphical user interface(GUI)Presents program control functions,output to users,and input from users Pictures,icons,and other graphical elements Cengage Learning 2015 40The World Wide Web(contd.)World Wide Web:Berners-Lees name for system of hyperlinked HTML documents Qui

45、ck acceptance in scientific research community 1993:first GUI program(Mosaic)Read HTML Used HTML hyperlinks for page-to-page navigation First Web browser widely available for personal computers Cengage Learning 2015 41The World Wide Web(contd.)Easy way to access Internet information Provided by func

46、tional system of pages connected by hypertext links Profit-making potential Netscape Communications founded in 1994 Netscape Navigator Web browser(based on Mosaic)Microsoft:Internet Explorer(most widely used)Mozilla Firefox:Netscape Navigator descendant Number of Web sites More rapid growth than the

47、 Internet itself Cengage Learning 2015 42The World Wide Web(contd.)More than 700 million Web sites 300 billion Web pages 2010 to 2011:number of Web sites doubled Cengage Learning 2015 43 Cengage Learning 2015 44FIGURE 2-3 Growth of the World Wide Web Cengage Learning 2015The Deep Web Non-permanent W

48、eb pages can be created based on customized response to users search Example:search for“online business”book on A Deep Web:information that is stored in databases and is accessible to users through Web interfaces Potentially trillions of Web pages available using deep Web Cengage Learning 2015 45Dom

49、ain Names Cengage Learning 2015 46 Cengage Learning 2015 47FIGURE 2-4 Commonly used domain names Cengage Learning 2015Markup Languages and the Web Text markup language Specifies set of tags inserted into text Markup tags(tags)Formatting instructions Web client understands HTML Most commonly used Web

50、 markup language Subset of older Generalized Markup Language(SGML)Cengage Learning 2015 48Markup Languages and the Web(contd.)Extensible Markup Language(XML)Derived from SGML Mark up shared information Meta language User creates markup elements extending XML usefulness World Wide Web Consortium(W3C)