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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2.2. Architecture-<strong>Driven</strong>S<strong>of</strong>twareDevelopment 25<br />
Viewsarebasedontheideathatas<strong>of</strong>twarearchitectureistoocomplex<br />
tobedescribedinasinglestroke,orbyonetype<strong>of</strong>abstraction(thatiswhy<br />
wetalkedaboutstructures(plural)before).Multipleviewsarerequiredto<br />
completelydescribe<strong>and</strong>documentas<strong>of</strong>twarearchitecture. Each<strong>of</strong>those<br />
viewsaddressesaspecificset<strong>of</strong>concerns[IEEE-1471,2000]. Theguidelinesforcreatingviewsaredefinedinso-calledviewpoints,oneforevery<br />
type<strong>of</strong>view.Severalsets<strong>of</strong>thoseviewpointshavebeendefined[Kruchten,<br />
1995;H<strong>of</strong>meisteretal.,1999;Clementsetal.,2002a].<br />
Comparedtothe‘ADLapproach’this‘viewsapproach’ismoreadoptedby<br />
industry[Kruchtenetal.,2006],whereaviewtypicallyisadocumentthat<br />
consists<strong>of</strong>somemodelsordiagrams<strong>and</strong>explainingtext,<strong>and</strong>islessformal<br />
thanADL-typedescriptions<strong>of</strong>s<strong>of</strong>twarearchitecture.Whencomparingthe<br />
twoapproaches,itcanbeconcludedthattheADL-approachasinvestigated<br />
bytheresearchcommunityfocusesonin-depthdescription<strong>of</strong>s<strong>of</strong>twarearchitectures,whiletheviews-approachasusedbyindustryfocusesonbroad<br />
description<strong>of</strong>s<strong>of</strong>twarearchitectures[Medvidovicetal.,2002].<br />
Finally,wespecificallymentiontheUnified<strong>Model</strong>ingLanguage 1 (UML).<br />
Although UMLwasoriginallyintendedasalanguageforobject-oriented<br />
modelling<strong>of</strong>systems,ithasbeenusedforarchitecturedevelopmentaswell<br />
(see,forinstance,Chapter3<strong>and</strong>Langeetal.[2006]).Tosomeextentitcan<br />
beusedasanADL[Medvidovicetal.,2002]. Furthermore,UMLdiagrams<br />
are<strong>of</strong>tenusedinarchitectureviews.<br />
Inthisthesis,wemanipulatedifferenttypes<strong>of</strong>architecturalviewsto<br />
supports<strong>of</strong>twareevolution.Insomecases,wealsopartlydemonstratethe<br />
definition<strong>of</strong>newADLs.Asanexample,inChapter5wetransformonetype<br />
<strong>of</strong>viewintoanothertochecktheconsistency<strong>of</strong>behaviouralspecifications<br />
<strong>of</strong>s<strong>of</strong>twareembeddedinthecopiersdevelopedbyOcé.<br />
2.2.5 S<strong>of</strong>twareArchitectureEvaluation<br />
Animportantreasonforexplicitlyconsiderings<strong>of</strong>twarearchitectureasa<br />
separatetype<strong>of</strong>designactivityordocument,isthatitconstitutesthefirst<br />
opportunityfortheprediction<strong>of</strong>properties<strong>of</strong>thesystemunderdevelopment.Wedistinguishbetweentwotypes<strong>of</strong>propertiesorqualities<strong>of</strong>asystem:operationalproperties<strong>and</strong>development(i.e.,non-operational)properties[Bosch,2000].<br />
Thefirsttypeincludesthosepropertiesthatcanbe<br />
measuredbyobservingthesysteminoperation,suchasfunctionality,performance,reliability.Non-operationalproperties,ordevelopmentpropertiesinvolvethedevelopment<strong>of</strong>thesystem,suchas,maintainability,modifiability,portability,developmentcost<strong>and</strong>effort.<br />
1 http://www.uml.org(June2007)