Opening a UDP connection in Veins toward external server

Question

I'm using Veins 4.4 and I need to store some results in an outer server, so I would like to open a UDP connection toward it.

I've read several posts about using a TCP connection for the mobility in Veins,and I understood I should resort to the Inet module to open a connection. Although I don't need it for the mobility, but to send data to an external server.

Is there any suggestion?

I was trying to use the method processCommandFromApp method from inet/src/transport/UDP.cc class:

    void UDP::processCommandFromApp(cMessage *msg)
{
    switch (msg->getKind())
    {
        case UDP_C_BIND: {
            UDPBindCommand *ctrl = check_and_cast<UDPBindCommand*>(msg->getControlInfo());
            bind(ctrl->getSockId(), msg->getArrivalGate()->getIndex(), ctrl->getLocalAddr(), ctrl->getLocalPort());
            break;
        }
        case UDP_C_CONNECT: {
            UDPConnectCommand *ctrl = check_and_cast<UDPConnectCommand*>(msg->getControlInfo());
            connect(ctrl->getSockId(), msg->getArrivalGate()->getIndex(), ctrl->getRemoteAddr(), ctrl->getRemotePort());
            break;
        }
        case UDP_C_CLOSE: {
            UDPCloseCommand *ctrl = check_and_cast<UDPCloseCommand*>(msg->getControlInfo());
            close(ctrl->getSockId());
            break;
        }
        case UDP_C_SETOPTION: {
            UDPSetOptionCommand *ctrl = check_and_cast<UDPSetOptionCommand *>(msg->getControlInfo());
            SockDesc *sd = getOrCreateSocket(ctrl->getSockId(), msg->getArrivalGate()->getIndex());

            if (dynamic_cast<UDPSetTimeToLiveCommand*>(ctrl))
                setTimeToLive(sd, ((UDPSetTimeToLiveCommand*)ctrl)->getTtl());
            else if (dynamic_cast<UDPSetTypeOfServiceCommand*>(ctrl))
                setTypeOfService(sd, ((UDPSetTypeOfServiceCommand*)ctrl)->getTos());
            else if (dynamic_cast<UDPSetBroadcastCommand*>(ctrl))
                setBroadcast(sd, ((UDPSetBroadcastCommand*)ctrl)->getBroadcast());
            else if (dynamic_cast<UDPSetMulticastInterfaceCommand*>(ctrl))
                setMulticastOutputInterface(sd, ((UDPSetMulticastInterfaceCommand*)ctrl)->getInterfaceId());
            else if (dynamic_cast<UDPSetMulticastLoopCommand*>(ctrl))
                setMulticastLoop(sd, ((UDPSetMulticastLoopCommand*)ctrl)->getLoop());
            else if (dynamic_cast<UDPSetReuseAddressCommand*>(ctrl))
                setReuseAddress(sd, ((UDPSetReuseAddressCommand*)ctrl)->getReuseAddress());
            else if (dynamic_cast<UDPJoinMulticastGroupsCommand*>(ctrl))
            {
                UDPJoinMulticastGroupsCommand *cmd = (UDPJoinMulticastGroupsCommand*)ctrl;
                std::vector<IPvXAddress> addresses;
                std::vector<int> interfaceIds;
                for (int i = 0; i < (int)cmd->getMulticastAddrArraySize(); i++)
                    addresses.push_back(cmd->getMulticastAddr(i));
                for (int i = 0; i < (int)cmd->getInterfaceIdArraySize(); i++)
                    interfaceIds.push_back(cmd->getInterfaceId(i));
                joinMulticastGroups(sd, addresses, interfaceIds);
            }
            else if (dynamic_cast<UDPLeaveMulticastGroupsCommand*>(ctrl))
            {
                UDPLeaveMulticastGroupsCommand *cmd = (UDPLeaveMulticastGroupsCommand*)ctrl;
                std::vector<IPvXAddress> addresses;
                for (int i = 0; i < (int)cmd->getMulticastAddrArraySize(); i++)
                    addresses.push_back(cmd->getMulticastAddr(i));
                leaveMulticastGroups(sd, addresses);
            }
            else
                throw cRuntimeError("Unknown subclass of UDPSetOptionCommand received from app: %s", ctrl->getClassName());
            break;
        }
        default: {
            throw cRuntimeError("Unknown command code (message kind) %d received from app", msg->getKind());
        }
    }

    delete msg; // also deletes control info in it
}

I included the inet path as follows:

#include <inet/src/transport/udp/UDP.h>

and I call it as follows, by passing as input UDP_C_CONNECT message.:

cMessage *UDP_C_CONNECT;
void Inet::UDP::processCommandFromApp(UDP_C_CONNECT);

But when I run the simulation, it crashes, returning this error:

Errors occurred during the build.
Errors running builder 'OMNeT++ Makefile Builder' on project 'veins'.
java.lang.NullPointerException

1) Is there the correct way to set up the required connection?

2) Why I'm getting this error as soon as I include the inet path?

UPDATE I also tried another way to establish the connection:

std::string host;
host = "16777343";
int port = 5144;
Veins::TraCIConnection* connection;
connection = TraCIConnection::connect(host.c_str(), port);

but as soon as it load the plugin, then it's like it is waiting for something at time 0.0 without starting the generation of the nodes. Thanks for helping

Do you aim to *simulate* a connection to a server or to physically contact a computer on your network? Your question is not very clear on this and you seem to have attempted a mix of both. — Christoph Sommer, Feb 14 '17 at 23:33
@ChristophSommer I need to transfer the collected data from Veins, to a server on my computer. — moi, Feb 16 '17 at 08:41

score 1 · Answer 1 · answered Feb 16 '17 at 09:31

Simulations using OMNeT++ are C++ programs, so you can use the full range of libraries and system calls available to any C++ program. If you want to open a UDP connection to some other computer on your network, just create a UDP socket as you would in any C++ program, then send the data whenever needed.

Maybe the easiest way to go about writing this is to

start with a plain C++ program that has nothing to do with OMNeT++
move the part of the program that has to run before everything else into the initialize method of a module in your simulation, the rest to a handleMessage method.

Opening a UDP connection in Veins toward external server

1 Answers1