Issue - 1: Non-permeable scopes

["Maciej Szefler" <mbs@fivesight.com>]

All this talk about links reminds me of our first issue, non-permeable scope
semantics. To recap, adopting non-permeable scopes would mean that a link
status would not be visible outside a scope boundry until that scope
terminates. This amounts to an "isolation" property for links (where the
scope boundry behaves like a traditional nested transaction). The primary
benefit of this would be that in case of a fault, any link exiting the
faulting scope would always be negative, which would be more in line with
the behavior of deadpath elimination and transition condition evaluation (in
case of failure or elimination, the link status is always negative). This
would also encourage the proper use of fault handlers as an "undo"
mechanism. With permeable scopes, it is very easy to write processes that
"see into" a faulted scope, which works to defeat the whole fault handling
and compensation mechanism. 

-Maciej