互联网与万维网(英文教学)

Preparedby:MahmudMuhammadAbdullahi1of38Chapter1:IntroductiontotheInternet&theWorldWideWeb2of38BasicdefinitionsAnetworkisastructurelinkingcomputerstogethertoshareresourcesNetworkInterfaceCard(NIC):acardusedtoconnectacomputertoanetworkofothercomputers.UsersaccessanetworkthroughacomputercalledahostornodeServer-acomputerthatmakesaserviceavailabletoanetwork,runssoftwarethatcoordinatesinformationflowamongothercomputers3of38BasicdefinitionsClient:computersconnectedtoaserver.NetworkOperatingSystem:softwarethatrunsonaserver.Client/ServerNetworks:oneservercomputersharingitsresourceswithmultipleclientcomputers.LocalAreaNetwork(LAN):networkofcomputerslocatedclosetoeachother.4of38NewPerspectivesontheInternet,5eTutorial14Client/ServerLAN5of38BasicdefinitionsInternetinternationalnetworkofnetworks-basicallyhardware-usesastandardcommunicationprotocol-TCP/IPWorldWideWebanetworkprovidingaccesstotheinformationsuperhighwayusinggraphicalinterfaces(W3C)6of38ConnectingComputerstoaNetwork–WirelessNetworksBecomingmorecommonascostscontinuetodrop.Welcomeinorganizationsthatoccupyoldbuildings.Popularwithcompanieswhoseemployeesuselaptopcomputers.Usedbyschoolsinclassrooms,libraries,andstudylounges.Usedinhomes.7of38WirelessHomeNetworkNewPerspectivesontheInternet,5eTutorial18of38WideAreaNetworksWAN:anetworkofnetworksoraninternet.Internet:aworldwidecollectionofinterconnectednetworks;ownershavevoluntarilyagreedtoshareresourcesandnetworkconnections.9of38WideAreaNetworksWideareanetwork(WAN)-anetworkthatcoversawidearea,suchasseveralbuildingsorcities.Internet-thelargestWANinexistence.10of38Connectivity:CircuitSwitchingvsPacketSwitchingCircuitswitching:centrallycontrolledsingle-connectionmethodusedbymostlocaltelephonetraffictodayVulnerabletodestructionofsignalcontrolpointoranylinkinthesinglepaththatcarriesthesignal.11of38Connectivity:CircuitSwitchingvsPacketSwitchingPacket-switching:filesandmessagesbrokendownintopacketsandlabeledelectronicallywithcodesfortheiroriginanddestination.Packetstravelfromcomputertocomputeralongthenetworkuntiltheyreachtheirdestination.Routersdeterminethebestwayforapackettomovetowardsitsdestination.12of38Connectivity:CircuitSwitchingvsPacketSwitchingRoutersuseroutingalgorithmsprogramstodeterminebestpathforpackets.Packet-switchednetworksmorereliable:relyonmultipleroutersinsteadofcentralpointofcontrol.eachroutercansendindividualpacketsalongdifferentpathsifpartsofthenetworkarenotoperating.13of38OriginsoftheInternetEarly1960sbytheU.S.DepartmentofDefense(DOD).Majorresearchprojectauthorizedasapartofnationalsecurity.Exploredwaystoconnectlargemainframecomputersandweaponsinstallationsdistributedallovertheworld.14of38OriginsoftheInternetDARPAresearchersconnectedfirstcomputerswitchesin1969.ARPANETgrewovernextthreeyearstoincludeover20computers.Initsearlydays,theInternetwascalledARPANET,consistedoftwonetworknodeslocatedatUCLAandStanford,connectedbyaphoneline.ComputerscommunicatedtoothercomputersonthenetworkbyusingNetworkControlProtocol(NCP).Protocol:collectionofrulesforformatting,ordering,anderror-checkingdatasentacrossanetwork.15of38TheInternettodayTodaytheInternethasgrowntoincludehundredsofmillionsofinterconnectedcomputers,cellphones,PDAs,televisions,andnetworks.ThephysicalstructureoftheInternetusesfiber-opticcables,satellites,phonelines,andothertelecommunicationsmedia.16of38InternetandWorldWideWeb:AmazingDevelopmentsTheInternetisalargecollectionofcomputersallovertheworldconnectedtooneanother.Oneofthemostamazingtechnologicaldevelopmentsofthe20thcentury.TheWorldWideWebisasubsetofcomputersontheInternetthathashelpedmakeInternetresourcesavailabletopeoplewhoarenotcomputerexperts.17of38InternetandWorldWideWeb:AmazingDevelopmentsNewWaystoCommunicateE-mailElectronicdiscussionsInstantmessagingInformationResourcesandSoftwareNewspapers&magazinesGovernmentdocumentsResearchreports&booksSoftwaredownloadsites18of38InternetandWorldWideWeb:AmazingDevelopmentsDoingBusinessOnlineElectronicstorefrontsCoordinateworldwideoperationsRecruitemployeesEntertainmentReviewrestaurants,movies,theater,musicaleventsandbooks.InteractivegamesFollowsportsteams19of38StructureoftheInternet20of38GrowthoftheInternetConnectionsarecheap&varied…..MoreresourcesarebeingconnectedNoofficialcontrolontheInternetTheStandardsarecriticalforthesuccessofnewinnovationsTechnologyadvancement&improvement21of38GrowthoftheInternetNumberofhostsconnectedtoInternetincludesonlycomputersdirectlyconnectedtotheInternet.Internettrafficnowcarriesmorefilesthatcontaingraphics,sound,andvideo,soInternetfileshavebecomelarger.22of38NewStructurefortheInternetTheInternethasbecomeoneofthemostamazingtechnologicalandsocialaccomplishmentsofthecentury.Computerslinkedtothisinterconnectednetworkarelocatedinalmosteverycountryoftheworld.BillionsofdollarschangehandseveryyearovertheInternet.23of38WhocontrolstheInternet?Noone???InternetSociety-•-anon-profit,non-governmental