Information exchanging between modules and Number of entries in Location table

[HuyTyskland]

Dear @riebl and everyone,

Currently I am working with Artery and Vanetza and I have two questions:

• I am doing some reading about the location table in GeoNet and I am curious how can I retrieve the number of entries (corresponding to the estimated number of neighbouring of an ITS)? I looked at the location table class and the SoftStateMap class and haven't figured out which function/variable I can use. I can add a counter to the location table class but I want to make sure not reinventing the wheel.

• With the Vanetza module, how can I make the dcc sub-module and router sub-module to exchange information. To be specific, I want to periodically send the number of entries from the first question from router sub-module to dcc submodules.

Kind regards, Huy Nguyen.

[fysch]

how can I retrieve the number of entries (corresponding to the estimated number of neighbouring of an ITS)?

You can get an iterator over all neighbours by calling LocationTable::neighbours(). std::distance(neighbours.begin(), neighbours.end()) should then give you the number of neighbours. However, if efficiency is important, it might be better to implement a new counter.

With the Vanetza module, how can I make the dcc sub-module and router sub-module to exchange information.

If you want communication between modules in Artery, the easiest way might be using omnetpp signals. The dcc submodule can then subscribe to the signal and the router can emit signals. There are plenty of examples in Artery, where you can get inspired.

[HuyTyskland]

hello @fysch , thank you for your reply. Indeed there are examples about emitting signals and subscribing signals in Artery as I am reading those.

However, I am a bit confused about the process so would you mind correcting me on this:

• Let say I want to emit CountSignal attached with variable Count from A.cc and A.ned from Router submodule. I can do the signal registration and signal emitting from A.cc and A.ned.
• However, I am confused about the process of subscribing and extracting information from the signal. Assume that I need the CountSignal at B.cc of the dcc submodule. With the emitting I describe, I will need to subscribe to CountSignal in the initialize(), and then I will write a function called receiveSignal(). Am I right? If so, I have a question about the set of inputs for receiveSignal():
  1. always the omnetpp cComponent: cComponent*
  2. simsignal_t signal: simsignal_t signal
  3. the type of the variable/object that attached with the signal (in my case it is int of the Count variable):int countValue
  4. always a cObject: `cObject Let say, I want to assign another variable, ReceivedCount, declared in B.h with Count. I can just do ReceivedCount = countValue`. Am I right?

[HuyTyskland]

Also, do I need to add anything to connections in Vanetza.ned files or anything similar to establish connection between dcc submodule and router submodule?

[fysch]

Am I right?

Yes, that seems correct.

Also, do I need to add anything to connections in Vanetza.ned files or anything similar to establish connection between dcc submodule and router submodule?

Afaik: no. Your sender-class just needs to inherit from omnetpp::cComponent and the receiver-class from omnetpp::cIListener. And in the .ned file of the sender-class you need to declare the signal by using @signal.

A more detailed explanation is also available in the Simulation Manual (chapter 4.14.2)

[HuyTyskland]

Ah I understand. Thank you very much

[HuyTyskland]

Hello @fysch , sorry for bothering you again.

the LocationTable::neighbours().std::distance(neighbours.begin(), neighbours.end()) seems like it does not work. The error when I used it is std::distance is not a class member and when I put using namespace std before the line, the error is that the range (of neighbour) has no member distance. I did some research on how to get the number of elements in a boost range but I haven't been able to find anything yet.

Would you mind helping me at this?

[fysch]

Assuming you are in src/artery/networking/Router.cc:

auto neighbours = getLocationTable().neighbours();
auto numNeighbours = std::distance(neighbours.begin(), neighbours.end());

If you are somewhere else, you need to find a way to get access to the LocationTable.

[HuyTyskland]

Hello @fysch , your suggestion works so thank you for that.

On the listener's side, there is an issue. So the class I am working right now is LimericDccEntity class inherited from DccEntityBase class inherited from omnetpp::cListener class. In the DccEntityBase class, the function receiveSignal() is defined. However that is not what I want. That is why I defined another receiveSignal() in LimericDccEntity. And I think that leads to my problem.

Problem: before declaring receiveSignal() in LimericDccEntity.h and defining it in LimericDccEntity.c and after subscribing the signal I want in LimericDccEntity, I have a signal called avgCBR and it is displayed as a vector. However, right after I declared and defined receiveSignal(), that caused avgCBR to disappear.

What might be the cause of this issue and do you have any suggestion on this? Is it an inheritance error or Artery does not allow me to do that?

[HuyTyskland]

I can solve it now. I misunderstood the subscribe() and that was why I could not receive anything.

No worries and thank you. I shall close this issue