EAI — The specification of EAIRouter and EAITimer as compound operators

Document: UML Profile and Interchange Models for EAI
Sections: 6.4.1.7 (EAIRouter) and 6.4.1.10 (EAITimer)

Description:
The specification of EAIRouter and EAITimer as compound operators does not correctly follow the FCM semantics for FCMCommands (which is the parent of EAICompoundOperator), for two reasons.

1. In order to promote the terminals of the primitive operators contained in the compound operator to terminals of the compound operator, there must be EAISources and EAISinks in contained in the compound operator corresponding to the external terminals. These are not specified in the discussion of the EAIRouter and EAITimer compounds.

2. An FCMCommand is a specialization of an FCMFunction, which invokes a single FCMOperation (see Figure 6-2). The content of the FCMCommand is simply a means to implement this operation. The expected FCM semantics are thus that, when all the inputs are provided, the operation is invoked, producing the specified outputs (via the internal composition, in the case of an FCMCommand). However, the semantics of EAIRouter and EAITimer, as described in Sections 6.4.1.7 and 6.4.1.10, are really to provide the functionality of the contained primitive operators as, effectively, multiple operations of the compound operator. This is not consistent with the FCM semantics, which implies a that an FCMCommand implements a single function from inputs to outputs.

Recommendation:
Do not implement EAIRouter or EAITimer as compound operators. Instead, simply provide the component primitive operators, as appropriate. (See subsequent issues for more detailed recommendations.)

see below