MESSAGES

In this section the user may define structures of messages with user's defined fields, besides the default fields (see 9.1). The declarations must have the heading MESSAGES. After this one or more message declarations follow. The declaration syntax is:

| <node identifier> | <message identifier> | (<list of field declaration>);

<node identifier> is the name of a I type node. Index must not be included in this declaration. The declaration defines the structure of the messages generated at that Input type node.

<message identifier> is an identifier that may be used by a CREATE instruction to generate messages with the declared structure. The CREATE instruction may be used in any node, except I type nodes

<list of field declaration> is a list of field declarations with the same syntax that the RECORD structure declaration.

Examples:

  ShipArr (I) :: ShipType := FTypeFreq; IT := EXPO(Tba[ord(ShipType)];
  ......................................
  TrainContr (A) ::
        ................................
        CREATE(Train) BEGIN
                        WCars := Round(TotalLoad / Capacity);
                        SENDTO(Yard) END;
  ......................................
  DECL
  TYPE St = (Freighter, Tanker, Barge)
  MESSAGES  ShipArr(ShipType: St; Load: ARRAY[1 .. 5] OF REAL; Displ: REAL);
            Train(WCars: INTEGER; Capacity: REAL);

In the node ShipArr, messages representing different types of simulated ships are generated. The characteristics (fields of the message) are: ship type, five quantities indicating different kinds of loads, and displacement. In the node TrainContr, according to conditions computed by a complex code, the decision of sending a message (train) to a yard is taken.