(20) port ::= "port" opt-multiple port-dir type-spec identifier ";"
(22) opt-multiple ::= [ "multiple" ]
(21) port-dir ::= "in" | "out"
Ports implement the data flow between components as a publish/subscribe
model. Ports have a name and a type and can be either out
(for
publishing data) or in
(for subscribing to a sibling out
port).
The optional multiple
qualifier defines a dynamic list of ports of
the given type, indexed by strings. In this case, ports are created or
destroyed dynamically be the codels.