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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7.8. Transformation 155<br />
SystemDefinition<strong>and</strong>Request TheSystemDefinitionrootelementinatarget<br />
modelcontainsallrequiredelementsthatdefinethedomainspecificpart<strong>of</strong><br />
anSMCcontroller.Assuch,thiselementcorrespondstoacompletesource<br />
model.<br />
ARequestencompassesrulesthatdeterminehowthatparticularmanufacturingrequest,suchasourunloadwaferfromFigure7.6onpage142,isplanned.Planningrulesinvolveaset<strong>of</strong>Tasks<strong>and</strong>correspondingpredecessorrelations.Additionally,aTaskcanbeanAndTaskoranOrTask.Inthesourcemodel,acompletestatemachineisusedtospecifyhowamanufacturingrequestistobeexecuted.So,wecreateaRequestelementinthe<br />
targetmodelforeveryStateMachineinthesourcemodel.<br />
Listing7.4onthenextpageshowstheATLspecification<strong>of</strong>thismapping.<br />
The RequestrulegeneratesaRequestelementforeveryStateMachinein<br />
thesourcemodel.ThisRequestcontainstaskswhicharecreatedbyother<br />
rules.Aswillbeexplainedlater,StatesorGuardsinthesourcemodelmay<br />
mapto Tasksinthetargetmodel. Becausethetasksinourtargetmodel<br />
maybecompositeinwhichcasetheyownothertasks,weshouldtakecare<br />
nottoselectallmodelelementsinthecompletestatemachinethatmap<br />
toaTask.Instead,foraRequestwediscardallStatesorGuardsinsidea<br />
CompositeStateotherthanthetop,<strong>and</strong>onpathsthatareonlyconditionally<br />
enabled(i.e.,byatransition’sguard).Tothisend,wedefinedtwoadditional<br />
generichelpers.First, rootOfSubTreetakesaset<strong>of</strong>statesasargument<strong>and</strong><br />
recursivelyselectsthe‘first’state<strong>of</strong>thatset(i.e.,theonewithoutincoming<br />
transitionsfromotherstatesintheset). Second, getTask<strong>Model</strong>Elementsis<br />
appliedtothat‘first’StatetocollectallmodelelementsthatmaptoaTask.<br />
Inessence,thishelpertakesaset<strong>of</strong>states<strong>and</strong>traversesthissetasa<br />
state‘tree’startingfromtheState(orGuard)itisappliedto,<strong>and</strong>bypassing<br />
CompositeStates<strong>and</strong>conditionalpaths.Duringthistraversalitcollectsall<br />
modelelementsitencountersthatmaptoaTask(i.e.,GuardsorStates).<br />
The SystemDefinitionrulegeneratesaSystemDefinitionelementthat<br />
correspondstothecompletesourcemodel.The behaviours, resources<strong>and</strong><br />
capabilityfeatures<strong>of</strong>theSystemDefinitionelementareboundtotheresult<strong>of</strong>otherrules.<br />
Inparticularfor behaviours<strong>and</strong> resourceswehadto<br />
usethe resolveTemphelperasthesearenotcreatedbythedefaulttarget<br />
elements<strong>of</strong>theinvolvedrules. Inthiscase,therelevantsourcemodelelementsareselectedbytwohelpersthataredefinedinthecontext<strong>of</strong>the<br />
transformationmoduleitself: behaviourStatesgivesallthesourcemodelelements(SimpleStates)thatmaptoaBehaviour,<strong>and</strong><br />
resourceActionsgives<br />
allthesourcemodelelements(≪claim≫Actions)thatmaptoaResource.<br />
TherequestfeatureisboundtotheelementscreatedbytheRequestrulefor<br />
allStateMachinesinthesourcemodel.
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