Model-Driven Evolution of Software Architectures - Software and ...
Model-Driven Evolution of Software Architectures - Software and ...
Model-Driven Evolution of Software Architectures - Software and ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
7.8. Transformation 153<br />
Foreveryelementinthesourcemodelthatmatchesthesourcepattern<br />
<strong>of</strong>arule,theelementsspecifiedbythetargetpatternarecreatedinthetargetmodel.NotethatinATL,thesourcemodelisread-only<strong>and</strong>thetarget<br />
modeliswrite-only.ThiscanalsobeseenfromListing7.2,whereonlythe<br />
sourcemodelisnavigatedtoinitialisethefeaturesreferredtointhebindings<strong>of</strong>thetargetpattern.Therefore,aspecificvalue-resolutionalgorithm<br />
isusedtoinitialisefeatures:iftheexpression<strong>of</strong>abindingreferstoanother<br />
targetelement(createdbythesamerule)itissimplyassigned,ifitrefers<br />
toasourceelementitisresolvedbyapplication<strong>of</strong>therulethatmatches<br />
thatsourceelement<strong>and</strong>takingthedefault(first)targetelement.<br />
Forcaseswheretherequiredtargetelementisnotthedefaultelement<br />
<strong>of</strong>anotherrule,ATL<strong>of</strong>fersthe‘resolveTemp’construct,aso-calledhelper<br />
operation. Ittakesasourcemodelelement<strong>and</strong>areferencetoaspecific<br />
targetelement<strong>of</strong>thematchingruleasinputparameters.InListing7.2,for<br />
example,thisisdoneinthebinding<strong>of</strong>thebehaviourfeature.Inthiscases.<br />
behaviourStateevaluatestoaSimpleStatethatismatchedbyanotherrule<br />
withmultipletargetelements,<strong>of</strong>whichthe ‘b’targetelementisselected<br />
tobindtothatfeature.<br />
Helpersaretypicallydefinedinthecontext<strong>of</strong>ametamodelelement<strong>and</strong><br />
effectivelyaddafeatureoroperationtoinstances<strong>of</strong>thatelement(cf. the<br />
use<strong>of</strong>OCLdefinitionconstraintsinListing7.1onpage144).Alternatively,<br />
ahelpercanbedefinedwithoutanycontext. Then,thedefaultcontext<strong>of</strong><br />
thecompletetransformationmodule,representedbythe thisModuleelement,applies.<br />
The resolveTemphelperisalsodefinedinthisdefaultcontext.<br />
7.8.2 BasicTarget<strong>Model</strong>Elements<br />
SimpleTask<strong>and</strong>Behaviour SimpleTaskscorrespondtomanufacturingactivities,<strong>and</strong>Behaviourscorrespondtotypes<strong>of</strong>manufacturingactivitiesinSMC<br />
systems. Therefore,tocreateSimpleTasks<strong>and</strong>Behavioursinthetarget<br />
modelweneedtoidentifyActionscorrespondingtomanufacturingactivitiesinthesourcemodel.AccordingtotheUMLSMCpr<strong>of</strong>ile,anActionthatcorrespondstoamanufacturingactivityhasnostereotype<strong>and</strong>isexecutedasaStateentryAction(see<br />
C3inListing7.1onpage144). ForeverysuchAction,aSimple-<br />
Taskneedstobecreated. ThisisspecifiedbytheruleinListing7.3on<br />
thenextpage.Itcontainsaguardthatusesthe behaviourStateshelperto<br />
onlymatchSimpleStatesthatmaptoaBehaviour.Notethatinthespecification,wedonotmapActionstoSimpleTasks,butinsteadwemaptheSimpleStatesinwhichtheyareexecutedtoSimpleTasks.ThisdoesnotaffectourmigrationresultssinceActionscorrespondingtoSimpleTasksare<br />
alwaysStateentryActions(byconstraintC3<strong>of</strong>theSMCpr<strong>of</strong>ile).
Change language