omnet++ Error in broadcasting message from a node

Question

Hello I am new to omnet++. I am trying to implement a simple broadcast service in omnet++ without using the inet. I have 6 nodes in ring topology. node[0] is the source and node[3] is the destination. So the idea is node[0] should create message and broadcast them through its gates till it reaches the desitination and delete it once it has reached.

I have attached my code below. I am not sure if there is a logical error here because i can compile the code. Also i am not sure if i have correctly used msg->getArrivalGateId() in my forward function, ideally i would need the getIndex() function. Please let me know how do i fix this. Any feedback is appreciated.

void broadcast::initialize()
{
if (getIndex() == 0) {
    MyMessage *msg = generateMessage();
    scheduleAt(0.0, msg);
    }
}
MyMessage *broadcast::generateMessage()
{
// Produce source and destination addresses.
int source = getIndex();  // our module index
//int n = getVectorSize();  // module vector size
int destination = (3);
int hopcount = 3;


char msgname[20];
sprintf(msgname, "Hello from-%d-to-%d, ", source, destination);

// Create message object and set source and destination field.
MyMessage *msg = new MyMessage(msgname);
msg->setSource(source);
msg->setDestination(destination);
msg->setHopcount(hopcount);
return msg;
}
void broadcast::handleMessage(cMessage *msg)
{
MyMessage *bmsg = check_and_cast<MyMessage *>(msg);
    if (bmsg->getDestination() == getIndex()) {

      delete bmsg;
      // Generate another one.
      EV << "Generating another message: ";
      MyMessage *bmsg = generateMessage();
      EV << bmsg << endl;
      forwardMessage(bmsg);
}
else {

        forwardMessage(bmsg);
  }
}
void broadcast::forwardMessage(MyMessage *msg)
{

// Increment hop count.
// msg->setHopcount(msg->getHopcount()+1);
int size = gateSize("gate");
int baseId = gateBaseId("gate$o");

for (int i = 0; i < size; i++){
        if(i != msg->getArrivalGateId()) {
            EV << "Forwarding message " << msg ;
            send(msg, baseId+i);
        }
}
}

** Event #1 t=0 routing.node[0] (broadcast, id=2) on selfmsg Hello from-0-to-3, (MyMessage, id=0)

send()/sendDelayed(): Cannot send message (MyMessage)Hello from-0-to-3, , it is currently in scheduled-events, being underway between two modules -- in module (broadcast) routing.node[0] (id=2), at t=0s, event #1 errorsnap

Rudi Rudi · Accepted Answer · 2019-06-12T09:16:26

gateId and gateIndex is two entirely different thing and should not be mixed. The ID is an opaque identifier and you cannot assume anything about it. i.e. you should not add, subtract to IDs and assume that it is valid.

You are on the right track, that you say that you should use the getIndex function. Typically, the index of the arriving message is available as msg->getArrivalGate()->getIndex(). And then use the send(msg, "gate$o", index) method to send on a specific gate.

omnet++ Error in broadcasting message from a node

1 Answers