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SimEvents: Which entity type should event actions be assigned to? Invoker type or target type?

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Kar Moh
Kar Moh on 30 Jun 2019
Edited: Kar Moh on 1 Jul 2019
Event actions of MATLAB discrete-event system should be named according to this rule: entityType + eventAction. The rule is rather easy to understand for events that target entities. But I got confused for events that target storages, especially testEntry and iterate.
For example, assume that we have 2 storages. Storage1 accepts entities of type Task, while Storage2 accepts entities of type Failure. We want the DES system to open or close the gate of Storage1 via testEntry, when a Failure entity arrives in Storage2. In this situation, should FailureEntry invoke TaskTestEntry (type of the storage that is affected) or FailureTestEntry (type of the storage that invokes the event action)?

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Accepted Answer

Krishna Akella
Krishna Akella on 1 Jul 2019
Hi Kar,
The testEntry method is invoked before an entity enters a storage. This method allows to either accept or refuse an entity from entering that particular storage. In the case of the storage for Task entities, the callback method name would be TaskTestEntry and for the Failure storage it would be FailureTestEntry.
For this example, when a Failure entity arrives into storage 2, an internal flag can be set in the block that would block Task entities from entering the block. When we are done processing the Failure entity, we can reset the flag so that we can start accepting entities into Storage 1. To check if any entities are waiting to enter storage 1, we can schedule a testEntry event for storage 1.
Regards,
Krishna

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Kar Moh
Kar Moh on 1 Jul 2019
Thanks a lot, Krishna. I summarize it as follows:
  • For events that target entities, the event action method is named according to the targetted entity type.
  • For events that target storages, the event action method is named according to the entity type of the targetted storage.
Note that a storage can accept only one type of entity.

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