英文文献及翻译计算机专业.docx
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英文文献及翻译计算机专业
NET-BASEDTASKMANAGEMENTSYSTEM
HectorGarcia-Molina,JeffreyD.Ullman,JenniferWisdom
ABSTRACT
Innet-basedcollaborativedesignenvironment,designresourcesbecomemoreandmorevariedandcomplex.Besidescommoninformationmanagementsystems,designresourcescanbeorganizedinconnectionwithdesignactivities.
Asetofactivitiesandresourceslinkedbylogicrelationscanformatask.Ataskhasatleastoneobjectiveandcanbebrokendownintosmallerones.Soadesignprojectcanbeseparatedintomanysubtasksformingahierarchicalstructure.
TaskManagementSystem(TMS)isdesignedtobreakdownthesetasksandassigncertainresourcestoitstasknodes.Asaresultofdesignresourcesandactivitiescouldbemanagedviathissystem.
KEYWORDS:
CollaborativeDesign,TaskManagementSystem(TMS),TaskDecomposition,InformationManagementSystem
1Introduction
Alongwiththerapidupgradeofrequestforadvanceddesignmethods,moreandmoredesigntoolappearedtosupportnewdesignmethodsandforms.Designinawebenvironmentwithmulti-partnersbeinginvolvedrequiresamorepowerfulandefficientmanagementsystem.Designpartnerscanbelocatedeverywhereoverthenetwiththeirownorganizations.Theycouldbemutuallyindependentexpertsorteamsoftensofemployees.Thisarticlediscussesataskmanagementsystem(TMS)whichmanagesdesignactivitiesandresourcesbybreakingdowndesignobjectivesandre-organizingdesignresourcesinconnectionwiththeactivities.Comparingwithcommoninformationmanagementsystems(IMS)likeproductdatamanagementsystemanddocumentmanagementsystem,TMScanmanagethewholedesignprocess.Ithastwotierswhichmakeitmuchmoref1exibleinstructure.
The1owertierconsistsoftraditionalcommonIMSSandtheupperonefulfillslogicactivitymanagementthroughcontrollingatree-likestructure,allocatingdesignresourcesandmakingdecisionsabouthowtocarryoutadesignproject.Itsfunctioningparadigmvariesindifferentprojectsdependingontheproject’sscaleandpurpose.Asaresultofthisstructure,TMScanseparateitsdatamodelfromitslogiccouldbringaboutstructureoptimizationandefficiencyimprovement,especiallyinalargescaleproject.
2TaskManagementinNet-BasedCollaborativeDesignEnvironment
EvolutionoftheDesignEnvironment
Duringanet-basedcollaborativedesignprocess,designerstransformtheirworkingenvironmentfromasinglePCdesktoptoLAN,andevenextendtoWAN.Eachdesignpartnercanbeasingleexpertoracombinationofmanyteamsofseveralsubjects,eveniftheyarefarawayfromeachothergeographically.Inthenet-basedcollaborativedesignenvironment,peoplefromeveryterminalofthenetcanexchangetheirinformationinteractivelywitheachotherandsenddatatoauthorizedrolesviatheirdesigntools.TheCoDesignSpaceissuchanenvironmentwhichprovidesasetofthesetoolstohelpdesignpartnerscommunicateandobtaindesigninformation.CodesignSpaceaimsatimprovingtheefficiencyofcollaborativework,makingenterprisesincreaseitssensitivitytomarketsandoptimizetheconfigurationofresource.
ManagementofResourcesandActivitiesinNet-BasedCollaborativeEnvironment
Theexpansionofdesignenvironmentalsocausedanewproblemofhowtoorganizetheresourcesanddesignactivitiesinthatenvironment.Asthenumberofdesignpartnersincreases,resourcesalsoincreaseindirectproportion.Butrelationsbetweenresourcesincreaseinsquareratio.Toorganizetheseresourcesandtheirrelationsneedsanintegratedmanagementsystemwhichcanrecognizethemandprovidetodesignersincaseoftheyareneeded.
Onesolutionistousespecialinformationmanagementsystem(IMS).AnIMScanprovidedatabase,filesystemsandin/outinterfacestomanageagivenresource.ForexamplethereareseveralIMStoolsinCoDesignSpacesuchasProductDataManagementSystem,DocumentManagementSystemandsoon.Thesesystemscanprovideitsspecialinformationwhichdesignuserswant.
ButthestructureofdesignactivitiesismuchmorecomplicatedthantheseIMScouldmanage,becauseevenasimpledesignprojectmayinvolvedifferentdesignresourcessuchasdocuments,draftsandequipments.Notonlyproductdataordocuments,designactivitiesalsoneedthesupportoforganizationsindesignprocesses.Thisarticleputsforwardanewdesignsystemwhichattemptstointegratedifferentresourcesintotherelateddesignactivities.Thatistaskmanagementsystem(TMS).
3TaskBreakdownModel
BasisofTaskBreakdown
Whenpeoplesetouttoaccomplishaproject,theyusuallyseparateitintoasequenceoftasksandfinishthemonebyone.Eachdesignprojectcanberegardedasanaggregateofactivities,rolesanddata.Herewedefineataskasasetofactivitiesandresourcesandalsohavingatleastoneobjective.Becauselargetaskscanbeseparatedintosmallones,ifweseparateaprojecttargetintoseverallower—levelobjectives,wedefinethattheprojectisbrokendownintosubtasksandeachobjectivemapstoasubtask.Obviouslyifeachsubtaskisaccomplished,theprojectissurelyfinished.SoTMSintegratesdesignactivitiesandresourcesthroughplanningthesetasks.
Net-basedcollaborativedesignmostlyaimsatproductsdevelopment.Projectmanagers(PM)assignsubtaskstodesignersordesignteamswhomaylocateinothercities.ThedesignersandteamsexecutetheirowntasksundertheconstraintswhicharedefinedbythePMandnegotiatedwitheachotherviathecollaborativedesignenvironment.Sothedesignersandteamsareindependentcollaborativepartnersandhaveincompactcouplingrelationships.Theyaredriventogetheronlybytheftdesigntasks.AfterthePMhavefinisheddecomposingtheproject,eachdesignerorteamleaderwhohasbeenassignedwithasubtaskbecomea1ow-classPMofhisowntask.AndhecandothesamethingashisPMdonetohim,re-breakingdownandre-assigningtasks.
SoweputforwardtworulesforTaskBreakdowninanet-basedenvironment,incompactcouplingandobject-driven.Incompactcouplingmeansthelessrelationshipbetweentwotasks.Whentwosubtaskswerecoupledtootightly,therequirementforcommunicationbetweentheirdesignerswillincreasealot.Toomuchcommunicationwil1notonlywastetimeandreduceefficiency,butalsobringerrors.Itwillbecomemuchmoredifficulttomanageprojectprocessthanusuallyinthissituation.Ontheotherhandeverytaskhasitsownobjective.FromtheviewpointofPMofasuperiortaskeachsubtaskcouldbeablackboxandhowtoexecutethesesubtasksisunknown.ThePMconcernsonlytheresultsandconstraintsofthesesubtasks,andmayneverconcernwhatwillhappeninsideit.
TaskBreakdownMethod
Accordingtotheabovebasis,aprojectcanbeseparatedintoseveralsubtasks.Andwhenthisseparatingcontinues,itwillfinallybedecomposedintoatasktree.Excepttherootofthetreeisaproject,alleavesandbranchesaresubtasks.Sinceadesignprojectcanbeseparatedintoatasktree,allitsresourcescanbeaddedtoitdependingontheirrelationship.Forexample,aSmall-Sized-Satellite.
Design(3SD)projectcanbebrokendownintotwodesignobjectivesasSatelliteHardware.Design(SHD)andSatellite-Software-Exploit(SSE).Anditalsohastwoteams.DesignteamAanddesignteamBwhichweregardasdesignresources.WhenAisassignedtoSSEandBtoSHD.WebreakdowntheprojectasshowninFig1.
Itisaliketomanageotherresourcesinaprojectinthisway.Sowhenwedefineacollaborativedesignproject’staskmodel,weshouldfirstclaimtheproject’stargets.Thesetargetsincludefunctionalgoals,performancegoals,andqualitygoalsandsoon.Thenwecouldconfirmhowtoexecutethisproject.Nextwecangoontobreakdownit.Theprojectcanbeseparatedintotwoormoresubtaskssincethereareat1easttwopartnersinacollaborativeproject.Eitherwecouldseparatetheprojectintostepwisetasks,whichhavetimesequencerelationshipsincaseofsomemorecomplexprojectsandthenbreakdownthestepwisetasksaccordingtotheirphase-to-phasegoals.
Thereisalsoanothertroubleinexecutingataskbreakdown.Whenataskisbrokenintosevera1subtasks;itisnotmerely“asimplesummotion”ofothertasks.Inmostcasestheirsubtaskscouldhavemorecomplexrelations.
Tosolvethisproblemweuseconstraints.Therearetimesequenceconstraint(TSC)andlogicconstraint(LC).Thetimesequenceconstraintdefinesthetimerelationshipsamongsubtasks.TheTSChasfourdifferenttypes,FF,FS,SFandSS.FmeansfinishandSpresentsstart.IfwesayTabbisFSandlagfourdays,itmeansTbshouldstartnolaterthanfourdaysafterTaisfinished.
Thelogicconstraintismuchmorecomplicated.Itdefineslogicrelationshipamongmultipletasks.
Hereisgivenanexample:
“TaskTAisseparatedintothreesubtasks,Ta,TbandTc.Buttherearetwomorerules.
TbandTccannotbeexecuteduntilTaisfinished.
TbandTccannotbeexecutedboth,thatmeansifTbwasexecuted,Tcshouldnotbeexecuted,andviceversa.ThisdependsontheresultofTa.”
SowesayTbandTchavealogicconstraint.Afterfinishingbreakingdownthetasks,wecangetatasktreeasFig,2illustrates.
4TMSRealization
TMSStructure
Accordingtoourdiscussionabouttasktreemodelandtaskbreakdownbasis,wecandevelopaTaskManagementSystem(TMS)basedonCoDesignSpaceusingJavalanguage,JSPtechnologyandMicrosoftSQL2000.Thetaskmanagementsystem’sstructureisshowninFig.3.
TMShasfourmainmodulesnamelyTaskBreakdown,RoleManagement,StatisticsandQueryandDataIntegration.TheTaskBreakdownmodulehelpsuserstoworkouttasktree.RoleManagementmoduleperformsau