Create a WSM inherented message - omnet++

Question

I would like to make a new message type called wsm_info.
In this message type, I want to include a vehicle structure, as it follows:
struct vehicle{
int vehicle_id;
Coord vehicle_pos;
float speed;
};
In the veins example there is a function called: prepareWSM that's declared in BaseWaveApplLayer.h. This function is a virtual WaveShortMessage* type.
If the wsm_info was inherented from WaveShortMessage I wouldn't need to write and declare a new prepareWSM for wsm_info, right?
So how can I make this wsm_info message inherented of WaveShortMessage?
I tried to write like this in the wsm_info.h:
class wsm_info : public WaveShortMessage
Instead of, that was written previously:
class wsm_info : public ::omnetpp::cPacket
But the error that I get is the following one:
cannot initialize a variable of type wsm_info * with an rvalue of type WaveShortMessage
The full code of my msg_info is below:
cplusplus {{
#include "veins/base/utils/Coord.h"
#include "veins/modules/messages/WaveShortMessage_m.h"
}}
class noncobject Coord;
class WaveShortMessage;
struct vehicle {
int vehicle_id;
Coord vehicle_pos;
float speed;
};
message wsm_info extends WaveShortMessage {
//Version of the Wave Short Message
int wsmVersion = 0;
//Determine which security mechanism was used
int securityType = 0;
//Channel Number on which this packet was sent
int channelNumber;
//Data rate with which this packet was sent
int dataRate = 1;
//Power Level with which this packet was sent
int priority = 3;
//Unique number to identify the service
int psid = 0;
//Provider Service Context
string psc = "Service with some Data";
//Length of Wave Short Message
int wsmLength;
vehicle data;
int senderAddress = 0;
int recipientAddress = -1;
int serial = 0;
Coord senderPos;
simtime_t timestamp = 0;
}
Can anyone take a look on my code and point me where is wrong and why? Thanks!

Answer 1

The msg_info.msg should have the following content:
cplusplus {{
#include "veins/modules/messages/WaveShortMessage_m.h"
}}
class noncobject Coord;
struct vehicle {
int vehicle_id;
Coord vehicle_pos;
float speed;
};
class WaveShortMessage;
packet wsm_info extends WaveShortMessage {
vehicle data;
}
You cannot use prepareWSM() because it creates a WaveShortMessage object which cannot be cast to wsm_info. Instead you may write a new method, for example:
In /veins/src/veins/modules/application/ieee80211p/BaseWaveApplLayer.h add:
#include "veins/modules/messages/wsm_info_m.h"
and in the class add the declaration:
wsm_info* prepare_wsm_info(std::string name, int dataLengthBits, t_channel channel, int priority, int rcvId, int serial=0);
In /veins/src/veins/modules/application/ieee80211p/BaseWaveApplLayer.cc add:
wsm_info* BaseWaveApplLayer::prepare_wsm_info(std::string name, int lengthBits, t_channel channel, int priority, int rcvId, int serial) {
wsm_info* wsm = new wsm_info(name.c_str());
// ... content similar to prepareWSM()
}
In order to set vehicle structure you can just write:
wsm_info* info = prepare_wsm_info(/* parameters */);
vehicle veh;
veh.speed = 60;
veh.vehicle_id = 3;
// ...
info->setData(veh);
Alternatively you can add parameters for vehicle in the definition of prepare_wsm_info().

Answer 2

If i get you right, you want to extend your wsm_info.msg, is that correct?
According to THIS question, you can modify your wsm_info.msg in the following way:
cplusplus {{
#include "veins/modules/messages/WaveShortMessage_m.h"
}}
class WaveShortMessage;
message wsm_info extends WaveShortMessage {
int vehicle_id;
Coord vehicle_pos;
float speed;
}

Answer 3

where must be declare wsm_info.msg ?in which folder?