Input-Output Pattern (IOP) defines
- cardinality (number of messages send or received from one node
to the service)
Message Exchange pattern (MEP) defines
- ditto IOP
- specifies the senders and receivers
- is there a use for not specifying senders and receivers?
- Conservation of messages: For any one message that is
sent by one node, one message is received by one node.
open issue: multicast protocols (should we represent multicast
messages differently at the interface level?)