英文文献及翻译计算机专业Word文档下载推荐.docx

英文文献及翻译计算机专业Word文档下载推荐.docx

《英文文献及翻译计算机专业Word文档下载推荐.docx》由会员分享，可在线阅读，更多相关《英文文献及翻译计算机专业Word文档下载推荐.docx（11页珍藏版）》请在冰点文库上搜索。

NET-BASEDTASKMANAGEMENTSYSTEM

HectorGarcia-Molina,JeffreyD.Ullman,JenniferWisdom

ABSTRACT

Innet-basedcollaborativedesignenvironment,designresourcesbecomemoreandmorevariedandcomplex.Besidescommoninformationmanagementsystems,designresourcescanbeorganizedinconnectionwithdesignactivities.

Asetofactivitiesandresourceslinkedbylogicrelationscanformatask.Ataskhasatleastoneobjectiveandcanbebrokendownintosmallerones.Soadesignprojectcanbeseparatedintomanysubtasksformingahierarchicalstructure.

TaskManagementSystem（TMS）isdesignedtobreakdownthesetasksandassigncertainresourcestoitstasknodes．Asaresultofdecomposition.al1designresourcesandactivitiescouldbemanagedviathissystem.

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,TMScanseparateitsdatamodelfromitslogicmode1.Itcouldbringaboutstructureoptimizationandefficiencyimprovement,especiallyinalargescaleproject.

2TaskManagementinNet-BasedCollaborativeDesignEnvironment

2.1EvolutionoftheDesignEnvironment

Duringanet-basedcollaborativedesignprocess,designerstransformtheirworkingenvironmentfromasinglePCdesktoptoLAN,andevenextendtoWAN.Eachdesignpartnercanbeasingleexpertoracombinationofmanyteamsofseveralsubjects,eveniftheyarefarawayfromeachothergeographically.Inthenet-basedcollaborativedesignenvironment,peoplefromeveryterminalofthenetcanexchangetheirinformationinteractivelywitheachotherandsenddatatoauthorizedrolesviatheirdesigntools.TheCoDesignSpaceissuchanenvironmentwhichprovidesasetofthesetoolstohelpdesignpartnerscommunicateandobtaindesigninformation.CodesignSpaceaimsatimprovingtheefficiencyofcollaborativework,makingenterprisesincreaseitssensitivitytomarketsandoptimizetheconfigurationofresource.

2.2ManagementofResourcesandActivitiesinNet-BasedCollaborativeEnvironment

Theexpansionofdesignenvironmentalsocausedanewproblemofhowtoorganizetheresourcesanddesignactivitiesinthatenvironment.Asthenumberofdesignpartnersincreases,resourcesalsoincreaseindirectproportion.Butrelationsbetweenresourcesincreaseinsquareratio.Toorganizetheseresourcesandtheirrelationsneedsanintegratedmanagementsystemwhichcanrecognizethemandprovidetodesignersincaseoftheyareneeded.

Onesolutionistousespecialinformationmanagementsystem（IMS）.AnIMScanprovidedatabase,filesystemsandin/outinterfacestomanageagivenresource.ForexamplethereareseveralIMStoolsinCoDesignSpacesuchasProductDataManagementSystem,DocumentManagementSystemandsoon.Thesesystemscanprovideitsspecialinformationwhichdesignuserswant.

ButthestructureofdesignactivitiesismuchmorecomplicatedthantheseIMScouldmanage,becauseevenasimpledesignprojectmayinvolvedifferentdesignresourcessuchasdocuments,draftsandequipments.Notonlyproductdataordocuments,designactivitiesalsoneedthesupportoforganizationsindesignprocesses.Thisarticleputsforwardanewdesignsystemwhichattemptstointegratedifferentresourcesintotherelateddesignactivities.Thatistaskmanagementsystem（TMS）.

3TaskBreakdownModel

3.1BasisofTaskBreakdown

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.

3.2TaskBreakdownMethod

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

4.1TMSStructure

Accordingtoourdiscussionabouttasktreemodelandtaskbreakdownbasis,wecandevelopaTaskManagementSystem（TMS）basedonCoDesignSpaceusingJavalanguage,JSPtechnologyandMicrosoftSQL2000.Thetaskmanagementsystem’sstructureisshowninFig.3.

TMShasfourmainmodulesnamelyTaskBreakdown,RoleManagement,StatisticsandQueryandDataIntegration.TheTaskBreakdownmodulehelpsusers