企業(yè)信息管理課件：Technologies for Information Management

TechnologiesforInformationManagementLearningoutcomesExplaintherelationshipbetweensoftware,hardwareandcommunicationscomponentsofinformationsystemsEvaluatethesuitabilityofdifferenttechnologycomponentsforinformationmanagementManagementissuesHowdoweselecttheappropriatetechnologyforourorganization?WhatisthemeaningandrelevanceofdifferenttechnologystandardsassociatedwiththeInternet?WhyweneedtounderstandhardwareTalkingtosuppliersaboutsolutionsSelectingthemostcost-effectivesolutionsTroubleshootingourown‘kit’Reducingthetotalcostofownershipofhardware(SeealsoChapter11)TechnoBabbleIn2003,ITrecruitmentconsultantComputerPeopleconductedasurveyintotheextentoftheproblemofITjargon.1,000officeworkersacrossvariousindustriesweresurveyedtoexamineperceptionsofITpersonnelandtoexplorehowcommunicationbetweenITprofessionalsandtheirnon-ITcolleaguescouldbeimproved.Overtwothirds(67%)ofofficeworkerssaidtheyfelt'bewildered'and'inadequate'duetonotunderstandingITprofessionals''techjargon'.Overhalf(56%)ofthosesurveyedsaidthatITprofessionals'speakanotherlanguage'withtwofifths(40%)sayingthattheyfeelITstaffareunawareoftheconfusionthattechjargoncauses.Source:ComputerPeopleDifferenttechnologyscales1.Organizationaltechnologyinfrastructure.

Includesdifferenttypesofcomputersystems2.Computersystemcomponents.

DifferentpartsofPCsandothersystems3.Networkingandtelecommunicationslinks.

Linkinginformationsystems4.Inter-organizationaltechnologyinfrastructure.

Standardsusedtosupporte-businessbetweenpartnersTechnologyinfrastructuremodelFigure3.1Afive-layermodeloftechnologyinfrastructureSource:AdaptedfromChaffey(2004)Client/serverarchitectureTheclient/serverarchitectureconsistsofclientcomputerssuchasPCssharingresourcessuchasadatabasestoredonmorepowerfulservercomputers.Processingcanbesharedbetweentheclientsandtheservers.Client/serverarchitectureissignificantsincemostmodernnetworkedinformationsystemsarebasedonthisstructure.Three-tierclient-serverarchitectureFigure3.2Atypicalthree-tierclientserverarchitectureReasonsforclient/serverDistributesprocessingpotentiallygivingbetterperformanceNotvitallydependentoncentralmainframeEnableslocaldatastorageforconvenienceEmpowersend-userstodeveloptheirownapplicationsEnablesremoteworking,e.g.salesrepresentativesProblemstobemanagedwithclient/serverCostofownershipInstabilityPerformanceLackofuserfocusLackofcontroloflocallydevelopedapplicationsanddata–forexample,isdataonlocalhard-diskbackedupDifferentformsofclientsDesktop–systemunitishorizontal,verticallyinatowerorminitowerconfiguration.PortableorLaptop.Handheld.Windowsterminalornetworkcomputer.TheFirstPersonalComputerFigure3.3ThefirstPersonalComputerSource:Rune’sPCMuseum(/rcm-001.jpg)Curator@APDAFigure3.4ApersonaldigitalassistantSource:Hewlett-PackardCompany,Inc.,PaloAltoCA()AlternativecomputingarchitecturesFigure3.5FivealternativecomputingarchitecturesSource:BIMDevelopmentsinservertypesBladeservers–Compact‘highdensity’serverscomprisingmicroprocessorsandmemoryonasinglecircuitboard.Clustering–Serversareconnectedtoincreasestabilityandperformance.Ifoneserverfails,anotherwilltakeover,ifthereisahighloadthenthiswillbesharedbetweenservers.Storageareanetwork(SAN)–Serverclusteringisusedtoconnectandmanagenetworkedstoragedevices.Gridcomputing–Theneedforpowerfulserversisreducedbythisapproachwhichsharesthepowerofclientmachinestosolvecomputationalproblems–theclientsareeffectivelyjoinedtobecomeapowerfulserver.ThebestknownapplicationofgridcomputingisSETI(SearchforExtraterrestrialIntelligence())inwhichover5millionpeoplearesharingunusedprocessortimeoftheirPCsinthesearchforsignalsfromouterspace.Mainframes–Mainframesarestillwidelyusedinlargeorganizations.Candeliverabettercost/performanceratiothanPCsinalargeorganization.Mini-computers–Likewise,mini-computerssuchastheIBMAS/400arestillwidelyusedforthecost/performanceandstabilitytheybringtobusinesses.Atypicale-commercesystemsarchitectureforane-tailerSource:Chaffey(2002)ThemaincomponentsofaPCFigure3.6ThemaincomponentsofaPCSource:

ProcessordefinedTheprocessorofacomputerisso-calledsinceitprocessesinstructionssuppliedbytheprogramcodewithintheoperatingsystemandapplicationssoftware.Ananalogywiththehumanbrainisoftenmadesinceitcontrolstheothercomputercomponentsinthesamewaythebraincontrolstheotherpartsofthebody.Anotheranalogyiswiththedriverofavehiclewhorespondstovariousinputstocontrolthecar.Butneitherthebrainnorahumancontrollingavehiclearereallyanalogoustotheprocessorworkingtogetherwithsystemsandapplicationssoftware.Selectioncriteriaforprocessors1.Manufacturer.Today,thetwomainPCprocessormanufacturersareIntelandAdvancedMicroDevices(AMD).OthermanufacturerssuchasHitachiandMotorolamakeprocessorsforothertypesofcomputer.2.Processorarchitecture.Seenextslide.3.Clockspeed.Theclockspeedgivesanindicationofhowfastachipcanprocessinstructions.Seenextslide.4.Systembus,Chipsetandmotherboard.

Themicroprocessorisonlyonepartofawiderrangeofchipsknownasachipsetwhichislocatedonthemotherboard–alargepieceofcircuitboardinsidethecomputer.Intelhasmanydifferentchipsetandmotherboardcombinations.IntelprocessordevelopmentNameDateTransistorsMicronsClockspeedMIPS808019746,00062MHz0.648088197929,00035MHz0.33802861982134,0001.56MHz1803861985275,0001.516MHz58048619891,200,000125MHz20Pentium19933,100,0000.860MHz100PentiumII19977,500,0000.35233MHz300PentiumIII19999,500,0000.25450MHz510Pentium4200042,000,0000.181.5GHz1,700Source:IntelIntelPentiumprocessorFigure3.7IntelPentiummicroprocessor(a)Microprocessor(b)MicroprocessorcircuitrySource:IntelCorporation(/pressroom/archive/photos/p4_photos.htm)ATIGraphicscardFigure3.8ATIRadeon9800graphicscardwith128MbRAMSource:ATITechnologies,Inc.,Ontario,Canada()Moore’sLawFigure3.9Moore’sLawSource:

/research/silicon/mooreslaw.htmRAMDefinedComputermemoryisusedtostoredataandprograms.Therearetwotypesofcomputerstorage.Temporaryorvolatilestoragewheredataisonlysavedwhenadeviceisswitchedonandpermanentstoragewherethedataissavedevenwhenadeviceispowereddown.TemporarystorageisbestknownthroughtheacronymRAM,standingforRandomAccessMemory.RAMisusedtostoretheoperatingsystem,applicationsandcurrentdataordocumentationandislinkedcloselytotheprocessortowhichinstructionsanddataaresuppliedfromRAM.RAMissimilartoourshorttermmemory–itisusedforissueswearecurrentlythinkingabout.-RAM(RandomAccessMemory)Figure3.10RAM(RandomAccessMemory)Source:KingstonTechnologyCompany,FountainValley,California(/press/primages/contents/asp)ROMDefinedEachcomputeralsocontainReadOnlyMemoryorROMwhichispermanentstoragewhichisusedtostoretheBIOSwhichisactivatedwhenacomputerisfirstswitchedonbeforetheoperatingsystemisloadedfromthehard-diskorotherpermanentmedia.WhenyouswitchaPCon,thefirsttextscreenwillalwaysrefertotheBIOS(BinaryInputandOutputSystem)loading.TheBIOSiseffectivelyconstant;butitcanbeupgradedifrequired.ThisformofROMisastandardcomponentoneachcomputeranddoesnotaffecttheperformanceofthesystem,soitisnotspecifiedinPCpurchase.StoragecapacitiesByte–madeupof8bitsusedtorepresentasinglecharacterordigitKilobyte–1,024BytesMegabyte–1,024KilobytesGigabyte–1,024MegabytesTerabyte–1,024Gigabytes

BitsandBytesStoragecapacityApproximatebytesPowerof2ExactBytesByteExactly1byte-1(eightbits,canrepresentonedigitorcharacter)KilobyteAthousandbytes2101,024MegabyteAmillionbytes2201,048,576bytes(1,024Kb)GigabyteAthousandmillionbytes2301,073,741,824(1,024Mb)TerabyteAtrillionbytes2401,099,511,627,776bytes1,024Gb)UnderstandingstoragecapacitiesLabelforvolume(size)?Gigabyte???Approxnumericamount(bytes)?1,000,000,000???Exampledataamount:AdatabaseforalargecompanyAdatabaseforasmallcompanyAhighresolutionphotoAlowresolutionphotoAcharacterExamplestorageamount:1?bcapacityserver120?bharddisk512?b

MemoryOldstyle720?bharddisk100?btostorenumbersinmobilephoneActivityCompletethetablebelowfillinginthegapsshownby?Labelforvolume(size):Byte,Terabyte,Kilobyte,MegabyteNumericamount:1,1,000,000:1,000,000,000,0001,000WhyisRAMimportantto

systemperformance?Figure3.11TherelationshipbetweenVirtualMemoryandRAM

Source:BIMPermanentstoragedefinedPermanentstorageisusedtostoretheoperatingsystem,applicationsanddata.UnlikeRAM,thestorageispersistentornon-volatilestorage–thedataisretainedafterthehardwareis‘powereddown’.Somesaypermanentstorageisequivalenttoourlong-termmemory.Butthehumananalogybreaksdownsincethesememoriesarenotretainedwhenweare‘powereddown’!Thereareawidevarietyofpermanentstoragedevicesandthesecanbeclassifiedaccordingtothetypeofstoragemediaandtheformofthestoragedevice.Themainmediatypesforpermanentstoragearemagnetic,optical,tapeandsolid-state.Themediamaybereadilyremovablefromthecomputeroritisafixedpartofthesystem.Ahard-diskdriveFigure3.12HarddiskdriveSource:SeagateTechnologyLLC(/newsinfo/newsroom/photo/D2h3.html)Opticaldrive–aDVDrewriterFigure3.13Opticaldrive–aDVDRewriterSource:PioneerNorthAmerican,Inc.,LongBeach,California(/pna/product/detail/

0,,2076-17573091-23143977.00html)TypesofopticalstorageRead-only–traditionalCDsandDVDusedformusicandfilm.Recordable(denotedbyCDRandDVDR)–Themediacanbewrittento,butoncetheyreachtheircapacityspacecannotbeclearedbydeletingexistingfiles.Rewritable(denotedbyCDRWandDVDRW)–themediacanbewrittentorepeatedly.CDscanholdaround640to700Mb.DVDscanholdeither4.7or7.95Gbdependingonwhethertheyaredoubleorsingle-sided.Amemorykey(stick)Figure3.14MemorykeyorstickSource:KingstonTechnologyCompany,FountainValley,California(/press/primages/contents/asp)FactorsinstoragemediaselectionCapacityofdeviceormedia.Speedofreadingandwritingmedia.Costofdevice.Costofremovablemedia.Thisisarelativelylowcostcomparedtothecostofthedevice.Needforpermanentorremovablemedia.Insomecaseswherearemovabledeviceisneededsuchasremovableharddiskthenthiscanaddtothecostofthedevice.Outputdevicesdefined Therearetwomainoutputdevicesforacomputersystemwhichareusedtointeractwithapplicationsanddata.

Thefirstisthemonitorordisplaywhichis,ofcourse,usedforinteractingwiththesystem,thesecondistheprinterwhichisusedforkeepinghardcopy.

Outputdevices

Usedforviewingoutputsfromasystem

Hardcopy

Printedoutputfromasystem,distinctfromsoftorelectroniccopyMonitorselectioncriteriaForm:Text(VDU)

raster/graphics(vector)basedResolution(pixels)VGA640by480SVGA800by600(designformanywebsites)XGA1024by768Size:14”,15”,17”,21”Colourdepth:16,256,15millionetc.Chooseagoodgraphicscardwhichenableshigherresolutionsthanthosechosenabove.ACRTmonitorFigure3.15ACRTmonitorfromViewSonic?Source:ViewSonicCorporation,Walnut,California()Aflat-screenmonitorFigure3.16Aflat-screenmonitorSource:ViewSonicCorporation,Walnut,California()MonitorselectioncritieraTypeCharacter,graphics(raster)orgraphics(vector)basedLaserprintervsInkjetResolutionMeasuredindotsperinchColourdepthThroughputMeasuredinpagesperminuteMulti-functionink-jetprinterFigure3.17Multi-functionink-jetprinterSource:Dell,Inc.,RoundRock,Texas()LaserprinterFigure3.18XeroxDocutechlaserprinterwithacapacityof500,000sheetspermonthSource:XeroxCorporation()DatainputdevicesDataiscapturedorinputbydifferenthardwaretoolsordevicesthatrelyonmovement,lightorsounde.g.Keyboard,mouseScannerBarcodereaderVoicerecognitionFingerprintreadersforsecurityDirectDigitalInputSelectionfactorsinputdevicesMiceandkeyboardarecommodities,socostreductioniskey.But:Cancauserepetitivestraininjuryinstaffifpoorquality(andotherissuesofergonomics)Wirelesskeyboardsandmicecanappearneater,butrequirebatteries,somoreoftenusedathomeratherthanbusinessMicrosoft?wirelesskeyboardandmouseFigure3.19Microsoft?wirelesskeyboardandmouseSource:MicrosoftComputernetworkdefined Thepurposeofacomputernetworkistotransferdatabetweendifferentcomputersorhardwaredevices.

Theclient/servermodelintroducedearlierrequiresacomputernetworktotransferdatabetweentheclientandservercomputer.Theservermayalsobeconnectedtootherhardwaredevicessuchasanetworkprinterorabackupsystemusinganetwork.

Computernetwork Acommunicationsystemthatlinkstwoormorecomputersandperipheraldevicestoenabletransferofdatabetweenthesecomputer.LANsandWANsComputernetworksareconstructedondifferentscales.Small-scalenetworksknownaslocal-areanetworks(LANs)canbesetupinanoffice,asmallbusinessorevenathome.Larger-scalenetworkswhichmayspanacity,country,theworldorspaceareknownaswide-areanetworks.TheseeffectivelylinktogetherdifferentLANs.Local-areanetwork(LAN)

Acomputernetworkthatspansalimitedgeographicareasuchasasingleofficeorbuilding.Wide-areanetwork Computernetworkscoveringalargeareawhichconnectsbusinessesindifferentpartsofthecountryordifferentcountries.AdvantagesanddisadvantagesofnetworksAdvantagesDisadvantages1.Facilitatessharingofinformation1.Organizationbecomesoverdependentonnetworksforaccesstoinformationandapplications2.Reducesduplicationofinformation2.Costofinitialsetup,usageandmaintenance3.Morerapidinformationtransferincludingreal-timeinformationaccess3.Reducedsecurityofinformationasinformationisexposedtoincreasedriskofinternalandexternalaccess,modificationanddeletion4.Reduceshardwarerequirementsthroughsharingofdevices4.Canfacilitateinformationoverloadase-mailsanddocumentsaremoreeasilydistributed5.Enablessoftwaretobemanagedcentrallyandreducesneedforlocalcopiesofsoftware6.Assistsininformationsecuritybyrequiringlog-inforaccesstocertaindata7.Enabletransformationofbusinessthroughe-businessapplications8.TheInternetprovidespotentialtoreachnewinternationalmarketsornewcustomergroupsatarelativelylowcostSelectinghome/SMEInternetconnectivityDatatransmitteddigitallyoverphonelinescanusearangeoftechniques.Digitaltelephoneexchangessupportanintegratedservicesdigitalnetwork(ISDN)standardthatallowsdatatransferratesthatareuptofivetimesfasterthanthetraditionalPOTS(‘PlainOldTelephoneService’).

AnISDNtelephonelineprovidestwoseparate‘channels’allowingsimultaneousvoiceanddatatransmissions.TheintroductionofAsymmetricDigitalSubscriberLine(ADSL)servicesmakesuseofexistingtelephonelinestoprovideveryhighdatatransferrates.ADSLisknownasasymmetricsincedownloaddatatransferratesaredifferent(higher)thanuploadrates.Suchhighspeedservicesareknownasbroadbandservices.

WhenusedtoaccesstheInternettheymakepracticalthetransmissionoflargervolumesofdatausedfordownloadingmusic,forexample,seeOnDemandDistribution()whichisusedtofeedmanymusicdownloadservicesinEuropeorstreamingvideo(seeforexampleBBCiBroadband,www.bbc.co.uk/broadband).Leasedlinesorsecurevirtualprivatenetworks(VPNs)withhigherspeedaccessusingtheT1standardareusedbylargerorganizations.TransmissionspeedThespeedatwhichdatacanbetransferredfromAtoBisgovernedbythechannelcapacity,whichismeasuredinbitspersecond(bps).Transmissionofasinglebitinasecondisequivalenttoonebaud,abinaryevent.Ratesareusuallymeasuredintermsofthousandsofbits/second(Kbit/sec),millionsofbits/second(Mbit/sec)orbillionsofbitspersecond(Gbit/sec).Ageneraltermoftenusedfordescribingcapacityisbandwidth.Thetechnicaldefinitionofbandwidthisthatitisameasureofcapacitygivenbythedifferencebetweenthelowestandhighestfrequenciesavailableforagivenmedium.SpeedofhomeInternetaccessPOTS–56Kb/secmodemISDN–256or512Kb/secADSL–Firstintroducedmainlyat512Kb/sec,but256Kb/s,1Mb/sand2Mb/soptionsnowcommonMonthlycapacitymaybecapped,e.g.1,15GbSatellite–similartoADSLUploadanddownloadmaximumfiguresdifferOthertelecommunicationscomponentsModem

Modulator-demodulatorusedtoconvertdatabetweendigitalandanalogueformwhentransmittingdataovertelephonelinesHubs

UsedtoconnectgroupsofcomputerstoanetworkBridgesandrouters

DeviceusedtoconnectnetworksandcontroltheflowofdatabetweenthemFirewall

HardwareusedtoincreasesecurityofpartofanetworkthroughpreventingunauthorizedaccessfrombeyondthenetworkRepeaters DeviceusedtoincreaseefficiencyoftransmissionoverlongdistancesEDIdefined Electronicdatainterchange(EDI)isthecomputer-to-computerexchangeofstructureddata,sentinaformthatallowsforautomaticprocessingwithnomanualintervention.ThisisusuallycarriedoutoverspecialistEDInetworks. DTI(2003)

Activity–Internetinfrastructurecomponents WritedownallthedifferenttypesofhardwareandsoftwareinvolvedfromwhenausertypesinawebaddresssuchastothewebsitebeingloadedInternetinfrastructurecomponentsFigure3.20PhysicalandnetworkinfrastructurecomponentsoftheInternetSource:Chaffey(2004)InternettimelineFigure3.21InternettimelineSource:Chaffey(2004)Informationexchangebetween

awebbrowserandwebserverFigure3.22InformationexchangebetweenawebbrowserandwebserverSource:Chaffey(2004)TheTCP/IPProtocolFigure3.23TheTCP/IPProtocolSource:Chaffey(2004)WhatistheWorldWideWeb?TheWorldWideWeb,or‘web’forshort,providesastandardmethodforexchangingandpublishinginformationontheInternet.Ifwetaketheanalogyoftelevision,thentheInternetistheequivalenttothebroadcastingequipmentsuchasmastsandtransmitters,andtheWorldWideWebisequivalenttothecontentofdifferentTVprogrammes.ThemediumisbasedonstandarddocumentformatssuchasHTML(HypertextMarkupLanguage)HTMLandXMLHTML(HypertextMarkupLanguage)

Astandardformatusedtodefinethetextandlayoutofwebpages.HTMLfilesusuallyhavetheextension.HTMLor.HTM.XMLoreXtensibleMarkupLanguage

Astandardfortransferringstructureddata,unlikeHTMLwhichispurelypresentational.ExampleHTMLformattingcodeHTML

code<P>Thistextis<B>bold</B></P><P>Thistextis<I>italic</P><P>Thistextis<U>underlined</U></P>Inbrowser:ThistextisboldThistextisitalicThistextisunderlinedExampleHTMLhyperlinkingcodeHTMLcode<AHREF="index.htm">Gotohomepage</A><BR><A>GototheBBCwebsite</A>Browser:GotohomepageGototheBBCwebsiteURLSanddomainnames Webaddressesarestructuredinastandardwayasfollows: http://www.domain-name.extension/filename.html Whatdothefollowingextensionsorglobaltopleveldomainsstandfor?.com.co.uk,..orgor.org.uk.gov.edu,.ac.uk.int.net.biz.infoMetcalfe’sLaw Metcalfe’slawwasfirststatedbyBobMetcalfe,whowasco-founderandformerchiefexecutiveofnetworkingcompany3Com.Hewasreputedtohavesaidinpresentationsmadeforthecompany:

‘Thepowerofthenetworkincreasesexponentiallybythenumberofcomputersconnectedtoit.Therefore,everycomputeraddedtothenetworkbothusesitasaresourcewhileaddingresourcesinaspiralofincreasingvalueandchoice.’MetadataMetadata

Adefinitionofthestructureandcontentofacollectionofdataordocument.‘Dataaboutdata’.HTMLhasalimitedcapabilityfordescribingdocumentsthroughHTMLmeta-tags.Thesearepresentedatthestartofthedocumentintheheaderarea.HTMLMetadataexample<HEAD><TITLE>Anintranetdocumentexample</TITLE><METAname="author"content="DaveChaffey"><METAname="keywords"content="phonedirectory,addressbook"><METAname="description"content="Anonlinephonebook"><METAname="date"content="2005-11-06T08:49:37+00:00"></HEAD>XMLMetadataexa