public void Execute() { try { var connector = _lookup.LookupConnector(_user1Id); var connectee = _lookup.LookupConnectee(_user2Id); connector.AttemptConnectionWith(connectee, _connectionInProgress); connector.WriteTo(_destination); } catch (InvalidConnectorIdException e) { _connectionInProgress.InvalidUserId(); } catch (InvalidConnecteeIdException e) { _connectionInProgress.InvalidOtherUserId(); } }