de.uka.ipd.sdq.pcm.seff
Interface GuardedBranchTransition

All Superinterfaces:

AbstractBranchTransition, Identifier

All Known Implementing Classes:

GuardedBranchTransitionImpl

public interface GuardedBranchTransition
extends AbstractBranchTransition

A representation of the model object 'Guarded Branch Transition'. Guarded Branch Transition Provides a link between a BranchAction and a nested ResourceDemandingBehaviour, which includes the actions executed inside the branch. It uses a guard, i.e. a boolean expression specified by a RandomVariable, to determine whether the transition is chosen. If the guard evaluates to true, the branch is chosen, otherwise if the guard evaluates to false another branch transition must be chosen. The guard may contain references to the service�s input parameters or component parameters. A component developer can specify complex boolean expressions by using the AND, OR, and NOT operations provided by the StoEx framework. As the domain expert may have characterised the parameters used in a guard with probability distributions, it might happen that a guard does not evaluate to true or false with a probability of 1.0. For example, the specification can express that a guard evaluates to true with a probability of 0.3, and to false with a probability of 0.7. In any case, the probabilities of the individual guards attached to all GuardedBranchTransitions contained in a BranchAction must sum up to 1.0. There is no predefined order in evaluating the guards attached to a BranchAction. This differs from programming languages such as C or Java, where the conditions on if/then/else statements are evaluated in the order of their appearance in the code. Such programming languages allow overlapping branching conditions (for example, if (X<10) //... else if (X<20) // ...), which are not allowed for the guards in GuardedBranchTransitions, because the missing order specification would lead to ambiguous boolean expressions and enable more than one guard to become true. If X would have the value 5, both conditions would evaluate to true if they would be used directly as guards in GuardedBranchTransitions. The correct specification of the guards in this case would be X.VALUE � 10 and X.VALUE � 10 AND X.VALUE � 20. Guards might lead to stochastic dependencies when evaluating variable characterisations inside a branched behaviour. For example, if the guard X.VALUE � 10 had formerly evaluated to true, and the RDSEFF uses X.VALUE inside the branched behaviour, the sample space of the random variable specifying the characterisation must be restricted, as the event that X takes a values greater than 10 cannot occur anymore. Therefore its probability is zero. Any variable characterisation always needs to be evaluated under the condition that all guards in the usage scenario�s path to it have evaluated to true.

The following features are supported:

• Branch Condition Guarded Branch Transition

See Also:

SeffPackage.getGuardedBranchTransition()

Field Summary

static String

copyright

Method Summary

PCMRandomVariable	getBranchCondition_GuardedBranchTransition() Returns the value of the 'Branch Condition Guarded Branch Transition' containment reference.
void	setBranchCondition_GuardedBranchTransition(PCMRandomVariable value) Sets the value of the 'Branch Condition Guarded Branch Transition' containment reference.

Methods inherited from interface de.uka.ipd.sdq.pcm.seff.AbstractBranchTransition

getBranchBehaviour_BranchTransition, setBranchBehaviour_BranchTransition

Methods inherited from interface de.uka.ipd.sdq.identifier.Identifier

getId, idHasToBeUnique, setId

Field Detail

copyright

static final String copyright

See Also:

Constant Field Values

Method Detail

getBranchCondition_GuardedBranchTransition

PCMRandomVariable getBranchCondition_GuardedBranchTransition()

Returns the value of the 'Branch Condition Guarded Branch Transition' containment reference.

If the meaning of the 'Branch Condition Guarded Branch Transition' containment reference isn't clear, there really should be more of a description here...

Returns:

the value of the 'Branch Condition Guarded Branch Transition' containment reference.

See Also:

setBranchCondition_GuardedBranchTransition(PCMRandomVariable), SeffPackage.getGuardedBranchTransition_BranchCondition_GuardedBranchTransition()

setBranchCondition_GuardedBranchTransition

void setBranchCondition_GuardedBranchTransition(PCMRandomVariable value)

Sets the value of the 'Branch Condition Guarded Branch Transition' containment reference.

Parameters:

value - the new value of the 'Branch Condition Guarded Branch Transition' containment reference.

See Also:

getBranchCondition_GuardedBranchTransition()