[PPT] - TheImpactofAspect-Oriented ProgrammingonFuture ApplicationDesign PowerPoint Presentation

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TheImpactofAspect-Oriented ProgrammingonFuture ApplicationDesign

AndreiPopovici InformationandCommunicationResearchGroup ISSeminarJan.17th,2001

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Outline

Thesoftwareworld

– components,objects,languages

Aspectsinthesoftwareworld

– theneedforaspects – whatareaspects – whentousethem – howtoworkwithaspects

implementationtechniques
availabletools
Theimpactofaspects

– throughoutacomponentslifetime – community-specificadaptations – application-awareenvironments(orcontexts)

Related

– researchareasandCStopics

SE,PL Ubi

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Thesoftwareworld

Component:

– unitofindependentdeployment – hasnopersistentstate – subjectto3rdpartycomposition

» [1]

Object:

– unitofinstantiation – encapsulatesstate&behavior – uniqueidentity

Intro Aspects Applications Related Intro Aspects Applications Related

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Decomposingcomponents

Component:typicallyconstructedusingone

language

Maindecompositionparadigm

– functional,object-oriented – thetyrannyofthedominantdecomposition

» [2]

Inpractice:adeployedcomponentconsistsof

manyobjects

Deployment∈ ComponentLifecycle

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Preamble

Whatistherealworldsecurity-aspectofmylife?

– lockthedoorofmyflatinthemorning – unlockoffice,unlockterminalatwork – lockscreen&lockofficeintheevening – unlockthedoorofmyplace..

1.Softwareworld, Component 2.Softwareaspect 3.Component lifetime Aspect~adspecere(lat.) – tolookat – particular appearancetoeye

rmind

Aspect~adspecere(lat.) – tolookat – particular appearancetoeye

rmind

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Aspectsmotivation

tyrannyofthemaindecompositionunit(OO)
Someconcernscannotbeexpressedina

modularway

– Whereislogginginorg.apache.tomcat?

Notinoneplace
Noteveninafew
Notinrelatedplaces
Notinoneplace
Noteveninafew
Notinrelatedplaces

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Costoftangledcode

Redundancy

– samefragmentinmoreplaces

Difficulttoreasonabout

– thebig-pictureoftanglingis notclear

Difficulttochange

– havetofindallthecode involved – thetobesuretochangeit consistently

» [3]

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AOP=..

Aspectsarewell-modularizedcrosscutting

concerns

Crosscuttingconcerns

– haveaclearpurpose – definemoduleboundaries,linesofdata-flow,set

fmethods,pointsofresourceutilization
Weaving:addaspectfunctionalitytoexisting

component

– hundredsofplaceschangedatatime Aspect + =

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ISSemminaryWS00/01 9 pointcuttouche(ctx):(ContextManager|BaseInterceptor)& receptions(*addContext(Contextctx)) aftertrackCtxChanges:touche(ctx) {Logger.log(“Contextchangedto”+ctx);} pointcuttouche(ctx):(ContextManager|BaseInterceptor)& receptions(*addContext(Contextctx)) aftertrackCtxChanges:touche(ctx) {Logger.log(“Contextchangedto”+ctx);} EachtimeContextManagerorBaseInterceptorreceivesan addContextcall EverythingwhichhappensintheclassContextManager Actiontotakeeverytimeapointdefinedbythecrosscut‘ touche’ isreached

AOPexample

Problem:trackcontextchanges

(tomcatexample)

ContextManager addContext BaseInterceptor addContext Intro Aspects Applications Related Intro Aspects Applications Related

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AOPtaxonomy

Joinpoints=allrelevantpointsinthe

executionofaprogram

Pointcuts=anamedsetofjoin-points(S)

– S&S,S|S,(S),!S

Aspect=pointcut+adviceaction
Adviceaction=similartocomponentblock

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Pointcutdefinitions

Someexamplesofprimitivepointcuts:

– *addContext(Context) matchesCtxMgr.addContext(Context) – **(Context) matchesCtxMgr.setContext(Context) too – **(..) matchesallmethodsofallclasses – public*(..) matchesallpublicmethods – CtxMgr matcheseverythingwhichhappensin theclassCtxMgr

Actionspecificators:

– (around(before(normalexecution)after)around)finally

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AOPimplementation

MostimplementationsassertJavaascomponent

language

Sourcepreprocessing

– semanticallyawarepreprocessor(AspectJ[5],HyperJ[4])

Objectinstrumentation

– changeobject-codeatload-time – e.g.,exchangeclass-loaderintheJVM(JOIE[6])

Monitoredruntimeenvironment

– Prose

BytecodetransformationexampleforJava Component classfiles Bytecode transformation rules Intro Aspects Applications Related Intro Aspects Applications Related

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AOPusage

AOPisusedfor:

– synchronization(e.g.,COOL[7]) – logging,errorhandling – distributionconcerns(e.g.,RIDL[7]) – contracts(pre-andpost-conditions)

..andcouldbeusedfor:

– contextsensitiveness – transactionalprocessing – join/setup/leave/teardownactions

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WhentouseAOP

thelifecycleofacomponent-

Designand implementation

release

Deployment environment

delivery

Adapt.

Changefactors

Deployment adaptations

Lateadaptations

Aspectsarecurrently usedinthisstage Intro Aspects Applications Related Intro Aspects Applications Related

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AOPforlateadaptations

Lateadaptationsinresponsetoenvironment

changes

Environmentchanges:

– policy/organizationalchanges

accesscontrol,security,privacy

– specialcase:informationspaces,mobilecomputing

recurringdeployment-likeadaptations

– service/usage-specific

principalinitiatingaservicecall
timeandcontextofaservicecall

– asynchronousenvironmentchanges

location,levelofservice,usageofsystemresources

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Scenarioslike..(1)

Idon’t undestand

Communityspecifickeys,encryptionalgorithmsandrules

(K,f) (K,f) (K,f) Intro Aspects Applications Related Intro Aspects Applications Related

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Scenarioslike..(2)

Getpart#2 Getsub-part#A,#B GetSWY

UploadMini-TM

functionalityin eachnodeofthe community

Glue(normal)

servicecallswith TMcoordination

Control

resources ..anopen-airfair-trade

GetSWX

..byinsertingacoordinationaspectintothe

participant’scomponent

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Scenarioslike..(3)

Aroboticenvironment:

– remotecontrolleddevices+sensors

ConsiderJINIsetupforLegoMindstorms

» [8,9]

Weaveanaspectintoallproxiesofall

servicesthatlogs

– whatcommandswereissued,atwhatpointin time,bywhom

Applications:

– replaypartsofthehistory

– querythepast(isthisafactoidaspect?) – performinverseoperations

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A.O.Contexts

Application-aware-context:

– basestation(associatedtothecontext)uploads andweavesatruntime(dynamically)aspectsinto allcomponentsjoiningtheenvironment – withdrawaspectsatruntime

Contextawareness:
Manyofthecurrentapproaches:

– intelligence(adaptationcapability)locatedinthe mobilesystem – contextispassive(e.g.,provideslocation-info)

allowsamobilecomputingdevicetoadapttochangingenvironmentconditions allowsamobilecomputingdevicetoadapttochangingenvironmentconditions

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Community-specific adaptations

Community-specificadaptations

– agroupofnodesdecidesdecidestoconsistently changeitsbehavior(e.g.,virtualcommunity)

AOPseemstobeagoodchoice

– consistentchanges – doaspectshavetobecomponent-specific[11]?

What’sthecompetitiondoing?

– designpatternsforconsistentchanges(factory)(-) – replacementofimplementation/libraries(--)

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Relatedwork

EnterpriseJavaBeans

– deploymentadaptations

CorbaQOS

– systempropertiesaroundfunctionalcalls[11]

Meta-ObjectProtocols

– openlanguagedefinitions(inpractice:extremely abstractandhardtounderstand)[10]

Configurable/openoperatingsystems

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Discussion

Impactonapplicationdevelopment?
Whatadaptationsarereallyorthogonal?
Howtodealwithcomponent-specific

adaptations

Securityproblemsforrun-timeextensions?
TowhatextentisAOPrelevantforaworldin

whichcomputerusetendstobecome pervasive?

Whataboutadaptationsof(dumb)devices?

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Who’swho

XeroxParc:AspectJ

– Kikzales,Lopes

U.ofTwente:compositionfilters(Sina)

– Aksitetal.

IBM:HyperJ/multidimensionalsep.ofconcerns

– Osherr,Tarr

N.E.U:adaptiveapplications

– Lieberherr

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References

[1]SzyperskyC:ComponentSoftware,BeyondObject-OrientedProgramming

,Addison- Wesley,1997,

[2]P.Tarr,HOsherr,W.Harryson,S.Sutton:NDegreesofSeparation:Multi-Dimensional

SeparationofConcerns.Proceedingsofthe21stInternationalConferenceonSoftware Engineering,May1999

[3]http://aspectj.org/documentation/papersAndSlides/OOPSLA-2000-demo_files/frame.htm
[4]http://www.research.ibm.com/hyperspace/HyperJ/HyperJ.htm
[5]http://www.aspectj.org
[6]TheJavaObjectInstrumentationEnvironment--http://www.cs.duke.edu/ari/joie/
[7]D:AlanguageFrameworkforDistributedProgrammingTechnicalReport

,XeroxPalo AltoResearchCenter,NumberSPL97-010,P9710047,February1997.

[8]http:www.legominstorms.de
[9]JanNewmarch:JiniandMindstorms,www.canberra.edu.au/java/mindstorms
[10]GregorKiksales:TheArtofMeta-ObjectProgramming
[11]J.Zinky,D.Bakken,R.Schantz:ArchitecturalSupportforQualityofServiceofCORBA

Objects.TheoryandPracticeofObjectSystems,April1997 Intro Aspects Applications Related Intro Aspects Applications Related

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Theend?

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