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 Chapter1. Introduction<br />
Figure 1.1:ASMLwaferscanner<br />
<strong>of</strong>controlcomponentsfromadeclarativespecification.Asaresult,therequiredeffortfordevelopment<strong>and</strong>maintenance<strong>of</strong>thecontrols<strong>of</strong>twarecan<br />
bereduced.<br />
Aproblemthatremainsisthemigration<strong>of</strong>existingcontrolcomponents<br />
tothisnewarchitecture. Apossibleapproachistostart-over<strong>and</strong>develop<br />
thesecomponentsfromscratchaccordingtothenewarchitecture. Inthis<br />
casethismeansthatforeachcontrolcomponentanewspecificationhas<br />
tobecreated. Unfortunately,theknowledgeincorporatedinthecode<strong>and</strong><br />
designs<strong>of</strong>alreadyexistingcontrolcomponentswillbelargelylostthisway.<br />
Consideringthefactthatthecurrentbehaviour<strong>of</strong>thesecomponentsdoes<br />
notneedtobechanged, thisconstitutesawaste<strong>of</strong>knowledge<strong>and</strong>resources,<strong>and</strong>anunnecessaryrisk.Analternativesolutionistoderivethespecifications<strong>of</strong>thesecomponentsforthenewarchitecturefromtheirexistingspecifications.<br />
Thescenariosketchedabove,whichisfullyexploredinChapter7,is<br />
aboutachangingorevolvings<strong>of</strong>twarearchitecture<strong>and</strong>illustratessome<br />
<strong>of</strong>theissuesweaddressinthisthesis. Manycompaniesareconfronted<br />
withsimilarscenarios.Anexampleinacompletelydifferentdomainisthe<br />
problem<strong>of</strong>makingexistinginformationsystemsaccessibleviatheWorld<br />
WideWeb.Thistypicallyalsorequiresarchitecturalchanges.Manyother<br />
scenarioscanbementionedthatinvolvearchitecturalchangesforreasons<br />
thatincludemaintainability<strong>and</strong>functionality.<br />
However, while<strong>of</strong>tenrequired, architecturalchangestypicallycome<br />
withasignificantrisk<strong>and</strong>areexpensivetoperform. Moreover,whenthe<br />
objective<strong>of</strong>suchchangesismaintainabilityimprovement,asinthescenarioabove,theirbenefitsareonlyexperiencedlateron.Thismakessuch
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