How to communicate with GZServer over a custom Socket-Client

edit

Hi Gazebo Community,

I have to publish some gazebo data to a windows application. For that I wanted to establish a socket communication. I generated a model plugin that is publishing data of interest. The data I can readout through the gazebo gui. For the next step I wanted create a standalone socket client to read the data published by gazebo. As a starter for socket communication the result confuses me.

Code for Client:

using namespace std;

int main(int argc, char* argv[])
{
    int client;
    int portNum = 11345; // NOTE that the port number is same for both client and server
    bool isExit = false;
    int bufsize = 1024;
    char buffer[bufsize];
    char* ip = "127.0.0.1";

    struct sockaddr_in server_addr;

    /// \brief Creating a new Socketconnection
    /// \param[ARG 1] Adress Domain of the Socket
    /// \param[ARG 2] Type of the Socket. Continous TCP Stream
    /// \param[ARG 3] Protocol, choosen by the OS
    client = socket(AF_INET, SOCK_STREAM, 0);

    if(client < 0){
        cerr << "\nError establishing socket..." << endl;
        exit(1);
    }

    cout << "\n=> Client has been created..." << endl;

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(portNum);
    server_addr.sin_addr.s_addr = inet_addr(ip);

    // Connecto to the Socket-Server
    if( connect( client, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0 ){
        cerr << "\nError establishing connection to Server..." << endl;
        exit(1);
    }
    cout << "=> Awaiting confirmation from the server..." << endl;
    recv(client, buffer, bufsize, 0);
    cout << "=> Connection confirmed..." << endl;


    do {
        recv(client, buffer, bufsize, 0);
        cout << buffer << " ";
    } while (true);

    cout << endl;
    cout << "\n=> Connection terminated.\nGoodbye...\n";
    close(client);

    return 0;
}

And the output is the following:

=> Client has been created...
=> Awaiting confirmation from the server...
=> Connection confirmed...
00000048

����؁�:topic_namepaces_init#
default
/gazebo
velodyne_hdl-3200000990

�������:publishers_init�
K
/gazebo/default/pose/local/infogazebo.msgs.PosesStamped
10.12.0.62 ��
E
/gazebo/default/pose/infogazebo.msgs.PosesStamped
10.12.0.62 ��
6
/gazebo/default/guigazebo.msgs.GUI
10.12.0.62 ��
@
/gazebo/default/responsegazebo.msgs.Response
10.12.0.62 ��
J
/gazebo/default/world_statsgazebo.msgs.WorldStatistics
10.12.0.62 ��
?
/gazebo/default/model/infogazebo.msgs.Model
10.12.0.62 ��
A

I assumed a stream of data and not one single output. Is it right what I'm seeing? How can I access for example the custom topic: /gazebo/veldoyne/scan_pose? Is that because I'm not encoding the ProtoBuf message in the right way and should I proceed with ign_transport lib to create a windows socket client for reading gazebo data?

Thanks for every advice.

Cheers, Rob