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I am asking about veins the vehicle network simulator.

In my veins application, I want to fetch some data available on a backend server through an API call.

I tried to use curl inside initialize function and I get this error:

/home/veins/workspace.omnetpp/simple_road/simple_road: symbol lookup error: /home/veins/src/veins/src/libveins.so: undefined symbol: _ZN5veins10MyVeinsApp7callAPIENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE

Simulation terminated with exit code: 127 Working directory: /home/veins/workspace.omnetpp/simple_road Command line: simple_road -m -n .:../../src/veins/examples/veins:../../src/veins/src/veins --image-path=../../src/veins/images -l ../../src/veins/src/veins omnetpp.ini

Environment variables: PATH=/home/veins/src/omnetpp-5.6.2/bin::/usr/lib/ccache:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/home/veins/bin:/home/veins/src/omnetpp/bin:/home/veins/src/sumo/bin:/home/veins/src/veins/bin LD_LIBRARY_PATH=/home/veins/src/omnetpp-5.6.2/lib::/home/veins/src/veins/src: OMNETPP_IMAGE_PATH=/home/veins/src/omnetpp-5.6.2/images

Code snippets:

void MyVeinsApp::initialize(int stage)
{
    DemoBaseApplLayer::initialize(stage);
    if (stage == 0) {
        // Initializing members and pointers of your application goes here
        callAPI("posts/1");
    }
    else if (stage == 1) {
        // Initializing members that require initialized other modules goes here
    }
}

size_t writeCallBack(void* contents, size_t size, size_t nmemb, void *userp) {
    ((std::string*)userp)->append((char*)contents, size * nmemb);
    return size * nmemb;
}

void callAPI(string path) {
    CURL* curl;
    CURLcode res;
    string buffer;

    curl = curl_easy_init();
    if(curl) {
        const string url = SERVER_URL + path;
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallBack);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer);
        res = curl_easy_perform(curl);
        curl_easy_cleanup(curl);

        EV << "code: " << res << ", data: " << buffer << endl;
    }
}
HussamElDin ElShaer
  • 1
  • Google revealed a problem just like this, maybe it if of help: https://github.com/openmm/openmm-tensorflow/issues/8 – Luuk Jun 01 '21 at 18:36
  • Have you been able to use curl from a small C++ program you wrote? As an OMNeT++ simulation is just a C++ program as well, it might be easier to first test everything in a small program and to then combine this with the simulator. If you need any compiler/linker flags to build, these go into the makefrag file. – Christoph Sommer Jun 02 '21 at 06:52

0 Answers0