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TechnologyInfrastructure:TheInternetandtheWorldWideWebChapter2©CengageLearning2015LearningObjectivesInthischapter,youwilllearn:Abouttheorigin,growth,andcurrentstructureoftheInternetHowpacket-switchednetworksarecombinedtoformtheInternetHowInternet,e-mail,andWebprotocolsworkAboutInternetaddressingandhowWebdomainnamesareconstructed22LearningObjectives(cont’d.)AboutthehistoryanduseofmarkuplanguagesontheWebHowHTMLtagsandlinksworkAbouttechnologiespeopleandbusinessesusetoconnecttotheInternetAboutInternet2andtheSemanticWeb33IntroductionAgrowingnumberofInternetusersareusingsmartphoneortabletSmartphonesaretypicallyonlytheaccessmethodindevelopingcountriesHistoryofInternet-capablemobilephonesFirstintroducedinlate-1990sSlow,unreliableservice,nokeyboards2001:Treo,Blackberryintroduced2009:Allmajorphonemanufacturershadproducts2011-2013:Lowerpricephonestargeteddevelopingmarkets4TheInternetandtheWorldWideWebComputernetworkTechnologyallowingpeopletoconnectcomputersInternet(capital“I)Interconnectedglobalcomputernetworksinternet(small“i”)GroupofinterconnectedcomputernetworksBasictechnologystructureSupportsnetworks,theInternet,ande-commerce55TheInternetandtheWorldWideWeb(cont’d.)WorldWideWeb(Web)SubsetofInternetcomputersIncludeseasy-to-useinterfaces66OriginsoftheInternetEarly1960sDefenseDepartmentnuclearattackconcernsPowerfulcomputers(largemainframes)LeasedtelephonecompanylinesSingleconnectionSingleconnectionrisksolutionCommunicateusingmultiplechannels(packets)1969AdvancedResearchProjectsAgency(ARPA)PacketnetworkconnectedfourcomputersARPANET:earliestnetwork(becametheInternet)Academicresearchuse(1970sand1980s)7NewUsesfortheInternetDefenseDepartmentnetwork:theoriginalgoalTocontrolweaponssystems;transferresearchfiles1970s:otherusesE-mail(1972)NetworkingtechnologyRemotefiletransferandcomputeraccessMailinglists1979:Usenet(User’sNewsNetwork)ReadandpostarticlesNewsgroups(topicareas)8NewUsesfortheInternet(cont’d.)LimitedInternetuseResearchandacademiccommunities1979–1989NetworkapplicationsimprovedandtestedDefenseDepartment’snetworkingsoftwareGainedwideracademicandresearchinstitutionuseCommoncommunicationsnetworkbenefitrecognizedSecurityproblemsrecognized1980s:personalcomputeruseexplosionAcademicandresearchnetworksmerged9CommercialUseoftheInternetNationalScienceFoundation(NSF)ProvidedfundingProhibitedcommercialnetworktrafficBusinessesturnedtocommerciale-mailprovidersLargerfirmsbuiltnetworks(leasedtelephonelines)1989:NSFpermittedtwocommerciale-mailservices(MCIMailandCompuServe)Commercialenterprisescouldsende-mailResearch,educationcommunitiessente-maildirectlytoMCIMailandCompuServe10GrowthoftheInternet1991FurthereasingofcommercialInternetactivityrestrictions1995:privatizationoftheInternetOperationsturnedovertoprivatelyownedcompaniesInternetbasedonfournetworkaccesspoints(NAPs)NetworkaccessprovidersSellInternetaccessrightsdirectlytolargercustomersUseInternetserviceproviders(ISPs)Selltosmallerfirmsandindividuals11GrowthoftheInternet(cont’’d.)Internethosts:directlyconnectedcomputersInternetgrowthOneofthemostsignificanttechnologicalandsocialaccomplishmentsoflastmillenniumNearlyeverycountryinvolvedUsedbymillionsofpeopleBillionsofdollarschangehandsyearly1213FIGURE2-1GrowthoftheInternet©CengageLearning2015TheInternetofThingsDevicescanbeconnectedtotheInternetControlledremotelyExamples:sensors,switches,opticalscannersTheInternetofthingsTermusedfortheseconnecteddevicesEstimatedsizeisninebillionProjectedtoreach35billionby202014Packet-SwitchedNetworksLocalareanetwork(LAN)NetworkofcomputerslocatedclosetogetherWideareanetworks(WANs)NetworksofcomputersconnectedovergreaterdistancesCircuitCombinationoftelephonelinesandclosedswitchesconnectingthemtoeachotherCircuitswitchingCentrallycontrolled,single-connectionmodelSingleelectricalpathbetweencallerandreceiver15Packet-SwitchedNetworks(cont’d.)Circuitswitching(cont’d.)WorkswellfortelephonecallsDoesnotworkaswellfor:SendingdataacrosslargeWANandinterconnectednetwork(Internet)Circuit-switchednetworkproblemConnectedcircuitfailureCausesinterruptedconnectionanddatalossSolutionPacketswitching:movedatabetweentwopoints16Packet-SwitchedNetworks(cont’d.)Packet-switchednetworkPacketsSmallpieceslabeledelectronically(origin,sequence,anddestinationaddress)TravelalonginterconnectednetworksCantakedifferentpathsMayarriveoutoforderDestinationcomputerCollectspacketsReassemblesoriginalfileore-mailmessage17RoutingPacketsRoutingcomputersDecidehowbesttoforwardeachpacketAlsoknownasrouters,gatewaycomputers,borderroutersGatewayfromLANorWANtoInternetBorderbetweenorganizationandtheInternetRoutingalgorithmsProgramsonroutingcomputersDeterminebestpathforpacket18RoutingPackets(cont’d.)Routingalgorithmsappliedtoroutingtable(configurationtable)informationRoutingtable(configurationtable)informationIncludeslistsofconnectionsProvidesrulesfor:SpecifyingconnectiontousefirstHandlingheavypackettrafficandnetworkcongestionVarietyofrulesandstandardsforcreatingpacketsHubs,switches,andbridgesDevicesthatmovepackets19RoutingPackets(cont’d.)RoutersconnectnetworksTranslatepacketsintostandardformatInternetbackboneRoutersandtelecommunicationlinesbetweenInternet’’smaincollectingpoints2021FIGURE2-2Router-basedarchitectureoftheInternet©CengageLearning2015PublicandPrivateNetworksPublicnetworkPublicavailabilityPrivatenetworkPrivate,leased-lineconnectionPhysicallyconnectsintranetstooneanotherLeasedlinePermanenttelephoneconnectionbetweentwopointsAdvantage:securityDrawback:costScalingproblem:addingcompanies22VirtualPrivateNetwork(VPN)ConnectionviapublicnetworksandprotocolsUsesIPtunneling(encapsulation)systemPrivatepassagewaythroughpublicInternetSecuretransmissionEncapsulationEncryptspacketcontent;placesinsideanotherpacketIPwrapper:outerpacketVPNsoftwareinstalledonbothcomputers“Virtual””sinceconnectionseemspermanentActuallyatemporaryconnection23IntranetsandExtranetsIntranetAnInternetwithintheboundariesoftheorganizationInterconnectedprivatenetworksExtranetAnInternetthatextendsbeyondtheorganizationandincorporatesnetworksofoutsideentitiesTechnologies(publicnetworks,privatenetworks,orVPNs)Independentoforganizationalboundaries24InternetProtocolsProtocol:collectionofnetworkdatarulesIncludestransmissionrulesComputersmustusesameprotocolARPANET:NetworkControlProtocol(NCP)Proprietaryarchitecture(closedarchitecture)ManufacturercreatesownprotocolOpenarchitecture(Internetcore)UsescommonprotocolFourkeymessage-handlingrulesContributedtotheInternet’ssuccess25TCP/IPReferstothetwopervasiveprotocolsusedtodayTransmissionControlProtocol(TCP)ControlsmessageorfiledisassemblyintopacketsbeforeInternettransmissionControlspacketreassemblyintooriginalformatsatdestinationsInternetProtocol(IP)SpecifiesaddressingdetailsforeachpacketLabelspacketwithoriginationanddestinationaddresses26IPAddressingInternetProtocolversion4(IPv4)Usedsince1981IPaddress32-bitnumberidentifyingcomputersBase2(binary)numbersystemComputersuseforinternalcalculationsDigit:0ora1(onoroffcondition)Fourbilliondifferentaddresses(232=4,294,967,296)RouterbreaksmessageintopacketsContainssourceanddestinationIPaddress27IPAddressing(cont’d.)DotteddecimalnotationFournumbersseparatedbyperiodsByte(8-bitnumber)Calledanoctet(networkingapplications)Binaryvalues:00000000to11111111Decimalequivalents:0to255ThreeorganizationsassignIPaddressesARINWhoisserverReturnsIPaddresslistownedbyanorganization28IPAddressing(cont’d.)NewdevicescreatinghighdemandforIPaddressesSubnettingUsereservedprivateIPLAN(WAN)addressesProvidesadditionaladdressspacePrivateIPaddressesIPnumbersnotpermittedonInternetpacketsNetworkAddressTranslation(NAT)deviceConvertsprivateIPaddressesintonormalIPaddresses29IPAddressing(cont’d.)InternetProtocolversion6(IPv6)ReplacesIPv4Addressespredictedtobeexhaustedin2015IPv4andIPv6notdirectlycompatibleIPv6majoradvantagesUses128-bitnumberforaddressesNumberofavailableaddresses:34followedby37zerosMorecomplexnotationsystem30ElectronicMailProtocolsElectronicmail(e-mail)FormattedaccordingtocommonsetofrulesClient/serverstructureE-mailserverComputerdevotedtoe-mailhandlingStores,forwardse-mailmessagesE-mailclientsoftwareReadsandsendse-mailCommunicateswithe-mailserversoftwareStandardizationandrulesareessential31ElectronicMailProtocols(cont’d.)TwocommonprotocolsSimpleMailTransferProtocol(SMTP)SpecifiesmailmessageformatDescribesmailadministratione-mailserverDescribesmailtransmissionontheInternetPostOfficeProtocol(POP)Sendsmailtouser’’scomputer;deletesfromserverSendsmailtouser’scomputer;doesnotdeleteAsksifnewmailarrived32ElectronicMailProtocols(cont’d.)MultipurposeInternetMailExtensions(MIME)SetofrulesforhandlingbinaryfilesInteractiveMailAccessProtocol(IMAP)SamebasicPOPfunctionsAdditionalfeaturesthatsupportuseraccesstoemailfromanycomputerOnedisadvantage:storageofe-mailmessageson

e-mailserver33WebPageRequestandDeliveryProtocolsWebclientcomputersWebclientsoftware(Webbrowsersoftware)SendsWebpagefilerequeststoothercomputers(Webservers)WebservercomputerWebserversoftwareReceivesrequestsfrommanydifferentWebclientsClient/serverarchitectureCombination:clientcomputers,servercomputers34WebPageRequestandDeliveryProtocols(cont’’d.)HypertextTransferProtocol(HTTP)InternetWebpagefiledeliveryrulesWebpagerequestusingWebbrowserUsertypesprotocolnameFollowedby“//:”charactersbeforethedomainnameUniformResourceLocator(URL)Combination:protocolname,domainnameLocatesresources(Webpage)onanothercomputer(Webserver)35EmergenceoftheWorldWideWebWebSoftwarerunningonInternet-connectedcomputersGeneratesnetworktrafficWebsoftware:largestsingletrafficcategoryOutpaces:e-mail,filetransfers,andotherdatatransmissiontrafficWebresultedfromnewwaysofthinkingaboutinformationstorageandretrievalKeytechnologicalWebelementsHypertextGraphicaluserinterfaces36TheDevelopmentofHypertext1945:VannevarBush:TheAtlanticMonthlyarticleVisionaryideas:futuretechnologyuses(Memex)1960s:TedNelsondescribedhypertextlinkingsystemDouglasEngelbart:experimentalhypertextsystem1987:NelsonpublishedLiteraryMachinesOutlinedprojectXanaduglobalsystemOnlinehypertextpublishingandcommerce37TheDevelopmentofHypertext(cont’d.)1989:TimBerners-LeeProposedhypertextdevelopmentprojectProvideddata-sharingfunctionalityDevelopedhypertextserverprogramcodeHypertextserverStoresHypertextMarkupLanguage(HTML)filesComputersconnectandreadfilesWebservers(today)HypertextserversusedontheWeb38TheDevelopmentofHypertext(cont’d.)HTMLSetofcodes(tags)attachedtotextDescribesrelationshipsamongtextelementsHypertextlink(hyperlink)PointstoanotherlocationSameoranotherHTMLdocument39GraphicalInterfacesforHypertextWebbrowserSoftware,e.g.,MozillaFirefoxorMSInternetExplorerUsersread(browse)HTMLdocumentsMovefromoneHTMLdocumenttoanotherTextformattedwithhypertextlinktagsinfileGraphicaluserinterface(GUI)Presentsprogramcontrolfunctions,outputtousers,andinputfromusersPictures,icons,andothergraphicalelements40TheWorldWideWeb(cont’d.)WorldWideWeb:Berners-Lee’snameforsystemofhyperlinkedHTMLdocumentsQuickacceptanceinscientificresearchcommunity1993:firstGUIprogram(Mosaic)ReadHTMLUsedHTMLhyperlinksfortonavigationFirstWebbrowserwidelyavailableforpersonalcomputers41TheWorldWideWeb(cont’d.)EasywaytoaccessInternetinformationProvidedbyfunctionalsystemofpagesconnectedbyhypertextlinksProfit-makingpotentialNetscapeCommunicationsfoundedin1994NetscapeNavigatorWebbrowser(basedonMosaic)Microsoft:InternetExplorer(mostwidelyused)MozillaFirefox:NetscapeNavigatordescendantNumberofWebsitesMorerapidgrowththantheInternetitself42TheWorldWideWeb(cont’’d.)Morethan700millionWebsites300billionWebpages2010to2011:numberofWebsitesdoubled4344FIGURE2-3GrowthoftheWorldWideWeb©CengageLearning2015TheDeepWebNon-permanentWebpagescanbecreatedbasedoncustomizedresponsetouser’ssearchExample:searchfor““onlinebusiness””bookonADeepWeb:informationthatisstoredindatabasesandisaccessibletousersthroughWebinterfacesPotentiallytrillionsofWebpagesavailableusingdeepWeb45DomainNames4647FIGURE2-4Commonlyuseddomainnames©CengageLearning2015MarkupLanguagesandtheWebTextmarkuplanguageSpecifiessetoftagsinsertedintotextMarkuptags(tags)FormattinginstructionsWebclientunderstandsHTMLMostcommonlyusedWebmarkuplanguageSubsetofolderGeneralizedMarkupLanguage(SGML)48MarkupLanguagesandtheWeb(cont’d.)ExtensibleMarkupLanguage(XML)DerivedfromSGMLMarkupsharedinformationMetalanguageUsercreatesmarkupelementsextendingXMLusefulnessWorldWideWebConsortium(W3C)MaintainsWebstandardsExtensibleHypertextMarkupLanguage(XHTML)HTMLversion4.0reformulationasXMLapplication4950FIGURE2-5Developmentofmarkuplanguages©CengageLearning2015MarkupLanguagesGeneralizedMarkupLanguage(GML)CreatesstandardelectronicdocumentformattingstylesSGML:versionofGMLAdoptedbyInternationalOrganizationforStandardization(ISO)SoftwareapplicationindependentNonproprietary;platform-independentOffersuser-definedtagsNotsuitedtorapidWebpagedevelopment;costlytomaintain;requiresexpensivetools;hardtolearn51HypertextMarkupLanguageHypertextelementsTextelementsrelatedtoeachotherHTMLPrevalentmarkuplanguagetocreateWebdocumentsW3CHTMLWorkingGrouppageDetailedHTMLversions;relatedtopicinformationHTMLextensionsFeaturesthatworkinspecificWebbrowsersHTMLversion5.0includesaudioandvideofeatureswithinthemarkuplanguageitself52HypertextMarkupLanguage(cont’d.)HTMLtagsInterpretedbyWebbrowserFormattextdisplayEnclosedinanglebrackets(<>)OpeningtagandclosingtagFormattextbetweenthemClosingtagPrecededbyslashwithinanglebrackets(</>)UsermaycustomizetaginterpretationsTags:generallywritteninlowercaseletters53HypertextMarkupLanguage(cont’’d.)One-sidedtagsRequireopeningtagonlyTwo-sidedtagsOptionalclosingtagClosingtagpositionveryimportantOpeningtagmaycontainoneormorepropertymodifiersFurtherrefinetagoperationOtherfrequentlyusedHTMLtagsGraphicsandtables5455FIGURE2-6TextmarkedupwithHTMLtags©CengageLearning201556FIGURE2-7TextmarkedupwithHTMLtagsasitappearsinaWebbrowser©CengageLearning2015HypertextMarkupLanguage(cont’’d.)HTMLlinksHyperlinksoninterlinkedpagesforma““web””LinearhyperlinkstructureReadsWebpageinserialfashionWorkswellwhencustomerfillsoutformHierarchicalhyperlinkstructureUsesanintroductorypage(homepage,startpage)linkingtootherpagesSitemapoftenavailableforhierarchicalsitesAnchortags5758FIGURE2-8Linearvs.nonlinearpathsthroughdocuments©CengageLearning201559FIGURE2-9ThreecommonWebpageorganizationstructures©CengageLearning2015ScriptingLanguagesandStyleSheetsObjecttagEmbedsscriptinglanguagecodeonHTMLpagesCascadingStyleSheets(CSS)ProvidemorecontroloverdisplayedpageformatStylesheetInstructionsstoredinseparatefileReferencedusingHTMLstyletagMaybeincludedinWebpage’sHTMLfile60ExtensibleMarkupLanguage(XML)WebdesigntoolForpresentingormaintaininginformationlists,dataIncludesdata-managementcapabilitiesHTMLcannotprovideXMLdifferentfromHTMLXML:notamarkuplanguagewithdefinedtagsXML:tagsdonotspecifytextappearanceonpage6162FIGURE2-10CountrylistdatamarkedupwithHTMLtags©CengageLearning201563FIGURE2-11CountrylistdataasitappearsinaWebbrowser©CengageLearning2015ExtensibleMarkupLanguage(cont’’d.)AdvantagesofXMLlistpresentationMoreeffectivelycommunicatesthemeaningofdataStrengthofXMLUsersmaydefinetheirowntags(weaknessaswell)6465FIGURE2-12CountrylistdatamarkedupwithXMLtags©CengageLearning201566FIGURE2-13CountrylistdatamarkedupwithXMLtagsasitwouldappearinInternetExplorer©CengageLearning2015ExtensibleMarkupLanguage(XML)(cont’’d.)SolutiontousertagdefinitionsCommonXMLtagsstandardsData-typedefinitions(DTDs)orXMLschemas2001:W3CreleasedsetofrulesforXMLdocumentsXMLvocabulary:setofXMLtagdefinitionsXMLfilesnotintendedtodisplayinbrowserExtensibleStylesheetLanguage(XSL)containsformattinginstructionsXMLparsers:formatXMLfilefordevicescreen6768FIGURE2-14ProcessingrequestsforWebpagesfromanXMLdatabase©CengageLearning2015HTMLandXMLEditorsHTMLdocumentcreationGeneral-purposetexteditororwordprocessorSpecial-purposeHTMLeditorsavailableWebsitedesigntoolsCreateandmanagecompleteWebsitesUploadentiresitefromPCtoWebserverExample:AdobeDreamweaverXMLfilesCreatedwithtexteditororprogramsExample:XMLSpy69InternetConnectionOptionsInternetSetofinterconnectednetworksOrganizationsconnectcomputersusinganetworkInternetaccessproviders(IAPs)orISPsProvideInternetaccesstoindividuals,businesses,otherorganizationsOfferseveralconnectionoptions70ConnectivityOverviewCommonconnectionoptionsVoice-gradetelephonelines,varioustypesofbroadbandconnections,leasedlines,wirelessDistinguishingfactorBandwidthAmountofdatatravelingthroughcommunicationlineperunitoftimeNetbandwidthActualspeedinformationtravelsSymmetricconnectionsProvidesamebandwidthinbothdirections71ConnectivityOverview(cont’d.)AsymmetricconnectionsProvidedifferentbandwidthsforeachdirectionUpstreambandwidth(uploadbandwidth)AmountofinformationfromusertotheInternetinagivenamountoftimeDownstreambandwidth(download,downlinkbandwidth)AmountofinformationfromtheInternettouserinagivenamountoftime72Voice-GradeTelephoneConnectionsUsedinearlydaysofWebPlainoldtelephoneservice(POTS)Usesexistingtelephonelines,analogmodemBandwidthbetween28and56KbpsDigitalSubscriberLine(DSL)protocolHighergradeofserviceUseDSLmodem(typeofnetworkswitch)IntegratedServicesDigitalNetwork(ISDN)FirsttechnologydevelopedusingDSLprotocolsuite73BroadbandConnectionsBroadband:connectionspeeds>200KbpsAsymmetricdigitalsubscriberline(ADSL)DSLprotocolprovidingbroadbandrangeserviceHigh-speedDSL(HDSL)Morethan768KbpssymmetricbandwidthCablemodemsTransmissionspeedstoserver:300Kbpsto1MbpsConnectionbandwidthsvarySubscriberscompeteforsharedresourceDSL:Privatelinewithnocompetingtraffic74BroadbandConnections(cont’d.)Ruralconnectionoptionissues:voice-gradelinesData-gradelinesinmosturbanandsuburbanlocations75Leased-LineConnectionsMoreexpensivetechnologiesClassifiedbyequivalentnumberoftelephonelinesincludedDS0(digitalsignalzero)Carriesonedigitalsignal(56Kbps)T1line(DS1)Carries24DS0lines(1.544Mbps)T3(DS3):44.736Mbps76Leased-LineConnections(cont’d.)LargeorganizationsrequireveryhighbandwidthNAPsandInternetbackboneroutingcomputersFramerelay,asynchronoustransfermode(ATM)Opticalfiber(insteadofcopperwire)Bandwidthdeterminedbyfiber-opticcableclassOC3(opticalcarrier3):156MbpsOC12:622MbpsOC48:2.5GbpsOC192:10Gbps77WirelessConnectionsPrevioussatellitemicrowavetransmissionsDownloadspeedsof500KbpsUploadhandledbyPOTSmodemconnectionToday:POTSmodemconnectionnotrequiredUsemicrowavetransmitterforuploads(150Kbps)ManywirelessnetworktypesnowavailableInternet-capablemobilephones,smartphones,gameconsoles,andnotebookcomputers78PersonalAreaNetworksAlsocalledpiconetsBluetoothDesigne