DescriptionofSoftwareArchitectures

軟件體系結(jié)構(gòu)描述

梁

鵬

武漢?學(xué)計算機學(xué)院

liangp@

Whyarchitecturedescription?

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Overview

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Whatisanarchitecturedescription?

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ISOstandardforarchitecturedescription

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Arch.representationinarchitectureviews

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Howtoobtainasetofarch.views

SoftwaredesigninUML

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Classdiagrams,statediagrams,sequencediagram,etc

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Whocanreadthosediagrams?

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Whichtypeofquestionsdotheyanswer?

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Dotheyprovideenoughinformation?

Whocanreadthosediagrams?

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Designer,programmer,tester,maintainer,etc.

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Client?

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User?

Whichtypeofquestionsdotheyanswer?

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Howmuchwillitcost?

Howsecureandreliablewillthesystembe?Howaboutmaintenancecost?

Howtoevolvethesystemtomeetnewrequirements?

WhatifrequirementAisreplacedbyrequirementB?

Buildingarchitecture

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Fire

Engineer

Plumber

StructureEngineer

Electrician

Analogywithbuildingarchitecture

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Overallpictureofbuilding(client)Frontview(client,“beauty”committee)

Separatepictureforwatersupply(plumber)

Separatepictureforelectricalwiring(electrician)etc

Architecturepresentationsinpractice

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Byandlargetwoflavors:

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Powerpointslides(boxandline)–formanagers,users,consultants,etc

UMLdiagramsinUMLnotations,fortechnicians

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Asmallsampleinpractice…

Eclipse1.0architecture

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Eclipse3.0architecture(evolution)

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EarthObservingSystem

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Decision-MakingSystem

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SA-Representations,13

?HansvanVliet,2012

直播系統(tǒng)

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支付寶錢包系統(tǒng)處理架構(gòu)

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So,…

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Differentrepresentations

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Fordifferentpeople

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Fordifferentpurposes

Overview

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Whatisanarchitecturedescription?

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ISOstandardforarchitecturedescription

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Architectureviews

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Howtoobtainasetofarch.views

Conceptualmodelofarchitecture

description[fromStd42010]

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Thinkaboutmodelastemplate

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Someterms/definitions(fromISOstandard)

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Systemstakeholder:individual,team,organization,orclassesthereof,anyonehavinganinterestinasystem

View:expressesthearchitectureofasystemfromtheperspectiveofspecificsystemconcerns

Viewpoint:establishestheconventionsfortheconstruction,interpretationanduseofarchitectureviewstoframespecificsystemconcerns

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view:viewpoint::program:programminglanguage

view:viewpoint::map:legend

Possibleconcerns(QAsfromISOstandard)

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Externalquality

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Developmentcost

Customerexperience(usability)Availability

Performance

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Internalquality

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EvolvabilityMaintainabilityTestabilityChangeability

…

Thetwinpeaks

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ArchitectingisNOTindependentfromReqsEng.

QualityattributeScenarios

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QualityattributescanbemadeSMARTbydefiningappropriatescenarios

Qualityattributescenariosaredefinedby:

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??

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Thesourceofthestimulus:HumanormachineThestimulus(event)

Theenvironmentorconditionwherethestimulusoccurs

Theresponsemeasure:Time,valueandlocation

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非功能屬性逐漸隨應(yīng)用情景的量化

ExamplePerformanceScenarios

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StimulusInitiateTransaction

ResponseTransactionprocessed

MeasureAveragelatency2s

Source

User

Artifact

System

EnvironmentNormaloperation

Importantbusiness-relatedQAs

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Time-to-marketCostprice

ReturnonInvestment(ROI)

TotalCostofOwnership(TCO)Lifetimeofthesystem

Integrationwithexisting(legacy)systemsMarketingfeatures

Etc.

ImportantDesign-timeQAs

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AN=ArchitecturalinNature

Q-Attribute

AN?

Architecturalissues

Modifiability

Yes

Modularity

Well-encapsulatedcomponents

Portability

Yes

Portabilitylayerorcomponents

Reusability

Yes

Well-specifiedcomponentsLoosecomponentcoupling

IntegrabilityInteroperability

Yes

CompatibleconnectionmechanismsComplete&consistentinterfaces

Testability

Yes

Modular&encapsulatedcomponentsIncrementalbuildsalongassociations

ImportantRun-timeQAs

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AN=ArchitecturalinNature

Q-Attribute

AN?

Architecturalissues

Dependability

?Timeliness

?Performance

?Reliability

?Availability

?Safety

?Security

Yes

WorstcaseresponsetimeAverageresponsiveness

MeanTimeToFailure(MTTF)AV=MTTF/(MTTF+MTTR)

AbsenceofcatastrophicfailuresResistancetounauthorizedusage

Usability

Partly

Properinf.flow&representationResponsiveness

Scalability

Yes

Hasmanyaspects

Contextofarchitecturedescription

[fromStd4201208 ]

Stakeholders

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?

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CustomerUserArchitect

RequirementsengineerDesigner

Implementer

Tester,integratorMaintainerProductmanager

Qualityassurancepeople

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Viewpointspecification

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[fromStd42010]

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ViewpointnameStakeholdersaddressedConcernsaddressedLanguage,modeling

techniques

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Exampleview:contextviewofSagitta2000

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?system?

Workflowmanager

?call/return?

Call

?call/return?

Call

Douane

?call/return?

Call

?filetransfer?

File

?filetransfer?

File

?system?

?system?Sagitta2000/SDDouane

?system?

Inkomendepoort

Uitgaandepoort

Douane

Douane

?call/return?

?call/return?

Call

?call/return?

?call/return?

Call

Call

Call

?call/return?

?call/return?

?call/return?

Call

?call/return?

Call

?call/return?

Call

Call

C

ll

Basisregistratieen-algoritmen

?system?

?system?

Klanten

Tarieven&maatregelen

Bel.dienst

Douane

?syste

?system?

?system?

Cod

Risico's

Vergunningen&zekerheden

Douan

Douane

Douane

?shared?HeffingenAfdelinginnings

?shared?KlantenBelasting-dienst

?shared?Tarieven&maatregelenDouane

?shared?Vergun-ningen&zekerhedenDouane

?shared?CodesDouane

?shared?Risico'sDouane

?system?

Inning

Inning

m?se

Exampleviewpointdefinition

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Name:Contextviewpoint

Stakeholders:systemowners,maintainersConcerns:systemboundaries,effectofchangesLanguage:UMLvariant

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?system?

Has

System

Owner

Call

?shared?DatabaseOwner

Call/Return

Has

Return

Fro

?filetransfer?

File

?call/return?

Call

(a)

(b)

m

T

Filetransfer

Owner

System

Shareddatabase

Uses

Overview

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Whatisanarchitecturedescription?

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ISOstandardforarchitecturedescription

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Architectureviews

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Howtoobtainasetofarch.views

Keyconceptsofviewsandviewpoints

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Aviewpointcoversoneormoreconcerns

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Viewpointsseparateconcerns

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Aviewconformstoaviewpoint

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Aviewconsistsofoneormoremodels

Anarchitecturedescriptionisorganizedinoneormoreviews

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The4+1viewmodel

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End-userFunctionality

ProgrammersSoftwaremanagement

Scenariousecase

IntegratorsPerformanceScalability

Systemengineers

TopologyCommunications

DeploymentViewpoint

ProcessViewpoint

ImplementationViewpoint

s

LogicalViewpoint

The4+1viewmodel

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CodeorganizationConfiguration,BuildingOS,DB,Middleware

LogicalorganizationAllocationoffunctionality

Use-caseview

What

Runtime

Physicaldistribution

ofHW&SW(topology)

Concurrency,Communication&Synchronization

Deploymentview

Processview

Implementationview

Logicalview

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UML符號簡介

Exampleofusecaseview

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ATM

BankClient

WithdrawMoney

TransferMoney

SaveMoney

4+1:Logical/ConceptualViewpoint

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Thelogicalviewpointsupportsthefunctionalrequirements,i.e.,theservicesthesystemshouldprovidetoitsendusers.

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Typically,itshowsthekeyabstractions(e.g.,classesandinteractionsamongstthem).

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Exampleoflogicalview

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CardReader

<<use>>

Display

<<send>

>

<<use>>

<<create>>

<<use>>

BankClient

<<send>>

<<use>>

<<send>>

<<use>>

<

<<use>>

Sensor

<use>>

AccountManager

Cashier

Dispenser

BankAccount

Keyboard

Transaction

Actor

dependency

Class

4+1:ProcessViewpoint

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Theprocessviewpointgivesthemappingoffunctionstoruntimeelements

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Ittakesintoaccountsomenonfunctionalrequirements,suchasperformance,systemavailability,concurrencyanddistribution,systemintegrity,andfault-tolerance.

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Exampleofprocessview

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2:withdrawrequest

1:authentifyuser

:casherinterface

3:confirm

:bankaccount

:BankClient

:withdrawer

5:dispatchnotes

4:authorize

:dispenser

4+1:ImplementationViewpoint

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Theimplementationviewpointfocusesontheorganizationoftheactualsoftwaremodulesinthesoftware-developmentenvironment.

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Thesoftwareispackagedinsmallchunks-programlibrariesorsubsystems-thatcanbedevelopedbyoneormoredevelopers.

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Exampleofimplementationview

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<<compile>>

<<trace>>

<<trace>>

Dispenser

<<file>>

dispenser.c

Sensor

Transmitter

<<file>>

client.c

Client

management

<<executable>>

client.exe

4+1:DeploymentViewpoint

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Thedeploymentviewpointdefineshowthevariouselementsidentifiedinthelogical,process,andimplementationviewpoints-networks,processes,tasks,andobjects-mustbemappedontothevariousnodes.

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Ittakesintoaccountthesystem'snonfunctionalrequirementssuchassystemavailability,reliability(fault-tolerance),performance(throughput),andscalability.

Exampleofdeploymentview

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ATMServer

<<file>>

dispenser.c

ATMTerminal

<<executable>>

client.exe

<<file>>

client.c

Using4+1viewinUML

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Usecaseview

Logical&processview

Implementationview

<<trace>>

<<trace>>

<<trace>

<<trace>>

<<trace>>

Deploymentview

Deploymentmodel

Testmodel

>

Implementati

onmodel

Designmodel

Analysismodel

Usecasemodel

TraceabilityofModels

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用例視圖

邏輯&過程視圖

實現(xiàn)視圖

《跟蹤》

《跟蹤》

《跟蹤》

《跟蹤》

《跟蹤》

部署視圖

UML2.0

實施模型

測試模型

實現(xiàn)模型

設(shè)計模型

分析模型

用例模型

RationalRosein4+1view

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RationalRosein4+1view

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ArchitecturalviewsfromBass(view=representationofastructur52e)

Moduleviews

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Moduleisunitofimplementation

Decomposition,uses,layered,class,datamodel

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Componentandconnector(C&C)views

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Theseareruntimeelements

Service,concurrency

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Allocationviews

Relationshipbetweensoftwareelementsandenvironment

Workassignment,deployment,implementation

Componentandconnectorviews

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Service:unitsthatinteroperatebyservicecoordinationmechanisms

Concurrency:todetermineopportunitiesforparallelism(connector=logicalthread)

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Allocationviews

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Deployment:howsoftwareisassignedtohardwareelements

Implementation:howsoftwareismappedontofilestructures

Workassignment:whoisdoingwhat

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Crosscuttingviewpoints(perspectives)

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Securityshowsupinfunctionalviewasuserauthentication,andindeploymentviewasfirewall

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Performanceshowsupinfunctionalviewincomponentcoupling,indeploymentviewasdistributedtopology

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Problems/pitfallsinarchitectureviews

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Poorlydefinedinterfaces

PoorlyunderstoodresponsibilitiesOverloadingtheview

Justdrawingthepicture

Inappropriatelevelofdetail“God”elements

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Exampleoverloadedview

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library

interface

servernodes

apps

ejb

dbms

server

Architecturalviewsinyourprojects

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Oneviewpointshouldfocusonthesystemfromtheperspectiveof(someorall)externalstakeholders

Oneoftheviewpointsshouldbeatechnicalviewpoint.

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Howtoexpressbusinessconcernsofstakeholdersinanunderstandableway?

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Someexamplesfrompreviousyears:

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Overview

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Whatisanarchitecturerepresentation?

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ISOstandardforarchitecturedescription

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Architectureviews

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Howtoobtainasetofarch.views

Howtodecideonwhichviews

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Whatarethestakeholdersandtheirconcerns?

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Whichviewsaddresstheseconcerns?

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Prioritizeandpossiblycombineviews

Categoriesofbusinessgoals[Ch16]

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MeetingfinancialobjectivesMeetingpersonalobjectivesMeetingresponsibilityofemployeesMeetingresponsibilitytocountryMeetingresponsibilitytosociety

Meetingresponsibilitytoshareholders

ManagingmarketpositionImprovingbusinessprocesses

Managingproduct’squalityandreputation

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Examplebusinessgoal

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Stakeholder:wewanttoprovideuserswithareliable,securerwaytoa