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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136 Chapter7. <strong>Model</strong>-<strong>Driven</strong>Migration<br />
Thisresultsinso-calledhazardousareasinwhichsubsystemscancollide<br />
<strong>and</strong>statetransitionsmustbeinducedsynchronouslytoensuresafety(e.g.,<br />
swappingWS:0<strong>and</strong>WS:1).<br />
Finally,conditionalexecution<strong>of</strong>manufacturingactivitiesneedstobe<br />
supported. Thatis,dependingoncertainconditionsinamachine,differentexecutionpathsforamanufacturingrequestmightbeactivated,each<br />
consisting<strong>of</strong>consecutivemanufacturingactivities. Anexample<strong>of</strong>sucha<br />
conditioninourwaferscannerexampleisthepresence<strong>of</strong>anotherwaferon<br />
thewaferstageatthemeasure-side.<br />
Duringmigration,sequence-dependentsetups,subsystemusage,concurrentexecution,<br />
synchronousexecution<strong>and</strong>conditionalexecutionare<br />
concernsthatneedtobeaddressed.Tothisend,wedefinedconcern-based<br />
transformationrulesthatmaptheseconcernsfromthelegacytothenew<br />
architecture.<br />
7.4 <strong>Model</strong>-<strong>Driven</strong>Migration<br />
Ideally,themigration<strong>of</strong>s<strong>of</strong>twarearchitecturesiscomplete,reproducible,<br />
reliable<strong>and</strong>automated. Weconsiderthestart<strong>and</strong>endpoint<strong>of</strong>themigrationasdifferentarchitecturalviews,referredtoasthesource<strong>and</strong>targetviewrespectively.ThisissimilartotheapproachforarchitecturereconstructionasdescribedbyVanDeursenetal.[2004].<br />
Anarchitecture<br />
viewisassociatedwithaviewpoint[IEEE-1471,2000],that,amongstothers,specifiesametamodelformodelsunderlyingtheprimarypresentation[Clementsetal.,2002a]<strong>of</strong>thatview.Inthischapterwefocusonthose<br />
models.<br />
Forthemigration<strong>of</strong>sourcemodelsintotargetmodelsweproposethe<br />
migrationapproachasshowninFigure7.3.Itusesatwo-stepprocessthat<br />
includesanormalisation<strong>and</strong>transformationstep.<br />
<strong>Model</strong>s<strong>and</strong>theirspecificationsare<strong>of</strong>tenincomplete<strong>and</strong>haveatendencytobecomeinconsistent<strong>and</strong>ambiguousovertime.Thismakesdirectlytranslatingasourcemodelintoatargetmodelinherentlydifficult.<br />
Thisisamplifiedfurtherbytoollimitations<strong>and</strong>thegenerallyinformal<br />
use<strong>of</strong>modellingparadigms<strong>and</strong>languagesinindustry(seeChapter3<strong>and</strong><br />
Langeetal.[2006]). Combinedwithincompleteorgenericmetamodels<br />
(e.g.,theUnified<strong>Model</strong>ingLanguage 1 (UML)metamodel),ornoexplicit<br />
metamodelsatall,amultitude<strong>of</strong>modelsbecomesconceivablethatallhave<br />
thesameintendedmeaning.<br />
Infact,ananalysis<strong>of</strong>howSMCconcernsareaddressedinthesource<br />
modelsforourmigration,revealedalargevariationintheusedidiom.This<br />
1 http://www.uml.org(June2007)
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