Model-Driven Evolution of Software Architectures - Software and ...
Model-Driven Evolution of Software Architectures - Software and ...
Model-Driven Evolution of Software Architectures - Software and ...
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70 Chapter4. Evaluation<br />
kind<strong>of</strong>componentsneedtobedefinedorhowsome<strong>of</strong>thealreadydefined<br />
componentsshouldcooperatetoimplementthedesiredbehaviour.Thisinformationcanbeincludedinthereferencearchitectureinaseparatedocumentwithoutaffectingtheexistingdocumentation.Byrealisingscenarios<br />
thiswaythescope<strong>of</strong>reuseisextended<strong>and</strong>thereferencearchitecture’s<br />
classificationmovesfromplatformtowardsproductline(seeSection4.2.2).<br />
Anexample<strong>of</strong>suchacookbookrecipewasthedescription<strong>of</strong>howtorealizesharing<strong>of</strong>hardwareresourceswithinanengine.Therecipeswerejust<br />
newreferencearchitecturedocuments. Infact,some<strong>of</strong>theexistingdocumentsalreadyweresuchrecipes,suchasthedocumentdescribinghow<br />
functioncomponentshouldlooklike, withoutactuallydefiningconcrete<br />
functioncomponents. Thesedocumentshadadifferentnaturethanthe<br />
otherdocumentsthatdescribespecificcomponents<strong>of</strong>thereferencearchitecture,likeascheduler.Figure4.4onthepreviouspageshowsthatmost<br />
<strong>of</strong>thescenariosfallinthiscategory<strong>of</strong>directscenarios.<br />
Theindirectscenarioswere,asusualinSAAM,partitionedintwosubsets:asubsetwith<br />
lowimpact<strong>and</strong>asubsetwith highimpact.Overallthis<br />
assessmentsessiondidnotdiscovermanydesignflaws. Thearchitects<br />
spentmost<strong>of</strong>theirtimeonthesinglehighimpact,highpriorityscenario<br />
(multiplesheetpaths).<br />
Theindirectscenariointeractionwasconsideredverybrieflyasonlya<br />
fewindirectscenarioswerediscovered.Itwasconcludedthatthosedidnot<br />
interact.<br />
4.4.4 OverallEvaluation<br />
Thisfinalstage<strong>of</strong>theassessmentinvolvedtheoverallevaluation,which<br />
resultedinaset<strong>of</strong>strong<strong>and</strong>weakpoints. Theset<strong>of</strong>strongpointsincludestheaforementioneduse<strong>of</strong>thereferencearchitecture<strong>and</strong>itsflexibility;most<strong>of</strong>theevaluatedscenariosaredirectlysupported.<br />
Theset<strong>of</strong>weakpointsincludesadesignflawthatpreventssupportfor<br />
multiplesheetpaths,whichisrequiredforduplexprinting,forinstance.<br />
Additionally, thereferencearchitectureseemedincompleteasitmissed<br />
severalcookbookrecipes. Forexample,recipesforsharinghardwareresources<strong>and</strong>reusingenginepartsamongstdifferentenginesinasingle<br />
copierarecurrentlynotincluded. Anotherweaknesswasthatvariation<br />
pointswerenotexplicitinthedocumentation. Relatedtothisissueisa<br />
missingstructurefordocumentinganinstantiation<strong>of</strong>thereferencearchitecture,anenginegeneration,withrespecttoitsdocumentation.Itwasnot<br />
clearhowconformanceto<strong>and</strong>deviationsfromthereferencearchitecture<br />
shouldbespecifiedbyprojectsthatdevelopsuchaninstantiation. Nevertheless,thisisimportantforthemaintainability<strong>of</strong>thereferencearchitecture<strong>and</strong>itsinstantiations.
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