SYSML2_ — Semantics of transfers across interfaces

In 7.16.1 Actions Overview, in the "Bindings and Flows Between Actions" section, it states in the last paragraph (italics added):

A send action usage includes an expression that is evaluated to provide the values to be transferred, and it specifies the destination to which those values are to be sent (possibly delegated through a port and across one or more interfaces – see also 7.12 and 7.14 on interfaces between ports).

However, the semantics of "delagation across an interface", per the italicized part above, are not described in 7.12 or 7.14, nor are they specified in 8.4.10 Interfaces Semantics.

Add transfer semantics to interfaces

This resolution updates the semantics of Ports and Interfaces to support automatic sending of Transfers between the participants of an Interface.

1. In the base PortDefinition Port:
   • The feature interfacingPorts is added, which collects, for all the Interfaces in which a Port is participating, all the other participant Ports.
   • The outgoingTransfers of a Port are constrained to be a subset of the incomingTransfersToSelf of the interfacingPorts of the Port. That is, every Transfer with a Port as its source must have a Port as its target that is connected to the first Port via an Interface.
   • Note that, when a Transfer is sent via a Port using a send action, the actual target does not have to be given because the target can be chosen from the interfacingPorts of the Port (if there is more than one interfacingPort it is not determined which is chosen). While a target can be given when sending via a Port, that target still must be one of the interfacingPorts – it is considered semantically invalid to send from a Port in any other way.
2. In the base InterfaceDefinition Interface:
   • The feature participant is redefined to have the type Port and to add the nested feature otherParticipants. For each participant of an Interface, the otherParticipants are the participants that are values of other ends of the _Interface.
   • For each participant, the otherParticipants are specified to be a subset of the interfacingPorts of the original participant, so that the interfacingPorts of a Port include the otherParticipants from all the Interfaces in which it participates.