OTS — The need for a default system SignalSet for failure scenarios.

The need for a default
system SignalSet for failure scenarios.
Malik originally requested this function so I'm raising it as an issue on
his behalf.

The following section is taken from the Activity srevice specification
orbos/2000-06-19.
P47: "If a SignalSet fails to produce Signals (e.g., it is physically
remote from the ActivityCoordinator and fails to respond to invocations),
then the completion status of the Activity is set to
CompletionStatusFailOnly, and the ActivityCoordinator should act
accordingly."

What does it mean by "should act accordingly", and what should be sent to
registered Actions if the (remote) SignalSet cannot be reached to produce
Signals?
Malik proposes a default SignalSet such as org.omg.SignallingFailure with
the signal "Failure", which should be sent to any Actions involved with the
unavailable SignalSet. This would require all Actions that cared about such
failure scenarios to be able to react to such a Signal. All Actions would
at least need to tolerate receiving such a Signal. We could go further and
define system Outcomes that Actions could return to the SignallingFailure
SignalSet and which could be percolated back up to Current::complete or
just define a new exception that could be thrown back up to
Current::complete. The important behaviour to provide is the ability for
the Actions in the failing Activity to be given the chance to register or
drive compensations or whatever recovery is necessary.

see above