Executor Changes. The duty of the executor part is to provide the bodies of all the guards that potentially must be evaluated in order to determine the reactions to be fired and, also, the bodies of the actions that can be fired as a reaction to an event; for Framework for adaptation through reconfiguration of components eDIANA: GA no.: 100012 D2.2-C instance, the implementation of the actions and guards that have been associated to all transition (normal or internal) of the statechart. One motivation for changing the executor part at run-time is the toleration of software faults. Upon the detection of those faults, the framework can replace the current one with another one. This way, in an easy form, there can be applied Backward-Recovery [16] algorithm to this particular part. MessageSending In a simple form, it can be a class having the mentioned elements plus some pseudo-state variables. For enabling the above mentioned run-time change in a generic manner, figure 5-3 illustrates one way to accomplish it. For that issue, an extra indirection is inserted that whenever a guard must be evaluated or an action must be executed, traps any exception launched from the current executor and, provided the necessary redundancy it an redirect the actual invocation to another version. MethodInvocation +evaluateGuard() +executeAction() Executor ExecutorHandler +execute(context: GlobalRepository) +getName(): String #actName: String Action Figure 5-3. Extra classes to trap possible exception of the executor part.
