Omnet++/INET: parameter added to cMessage becomes 0 when received - simulation

Question

In our simulation we added two fields to cMessage class as protected:
/* sequence number for log files */
long seqNo = 0;
/* timestamp at sending message */
simtime_t sendingTime;
and we add the following publics methods
public:
void setSeqNo(long n) {
this->seqNo = n;
}
long getSeqNo() {
return this->seqNo;
}
void setSentTime(simtime_t t) {
this->sendingTime = t;
}
simtime_t getSentTime() {
return this->sendingTime;
}
Now, when the server simulated application runs, before each message seding it performs:
pkt->setSeqNo(numPkSent);
pkt->setSentTime(simTime());
fprintf(this->analyticsCorrespondentNode, "PKT %u SENT AT TIME %f TO NODE %s \n", numPkSent, pkt->getSentTime().dbl(), d->clientAddr.get4().str().c_str());
On the other hand, when the message is received by the simulated application client if performs:
double recvTime = simTime().dbl();
fprintf(this->analyticsMobileNode, "RECEIVED PKT num. %d SENT AT TIME: %f RECEIVED AT TIME %f TRANSMISSION TIME ELAPSED %f \n", msg->getSeqNo(), msg->getSentTime().dbl(), recvTime, recvTime - msg->getSentTime().dbl());
The problem is that SeqNo is correctly written by the client as it had been set by the server before sending. Instead, the methods
msg->getSentTime.dbl()
always returns 0 in the client log file while it is correctly set by the server in the server log file. I don't understand why, maybe there's something strange happening in the conversion between cMessage to cPacket in the client application...do you know this?

Answer 1

In order to add own fields to a packet definition you should only prepare the definition in *.msg file. For example file FooPacket.msg:
packet FooPacket {
long seqNo;
simtime_t sendingTime;
// other fields...
}
Then, in your source file *.cc add:
#include "FooPacket_m.h"
The class FooPacket which derives from cPacket as well as all setter and getter methods will be generated automatically during the compilation - you will see the following files: FooPacket_m.h and FooPacket_m.cc.
When your client receives a message, you should check whether the type is the same as you expected and then cast it to FooPacket type. For example this way:
void handleMessage(cMessage *msg) {
if (dynamic_cast<FooPacket* >(msg)) {
FooPacket *pkt = check_and_cast<FooPacket* >(msg);
simtime_t t = pkt->getSendingTime();
}
// ...
}

Answer 2

It could be the conversion from cMessage to cPacket. Have you tried this?
Packet pk = check_and_cast<Packet *>(msg);
pk->getSentTime.dbl();
Also you can try to check if there is a problem with simtime_t double somewhere, try double for sentTime parameter