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QUdpSocket : simple communication between 2 Qt applications

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  • ODБOïO ODБOï

    hi @dheerendra ,
    I don't understand,
    i my server i have nothing to read, i only want to write. The reciver (2nd app) has to read (sk.receiveDatagram() ). am i missing something or you misunderstood my question ..?

    JonBJ Offline
    JonBJ Offline
    JonB
    wrote on last edited by JonB
    #9

    @LeLev
    @dheerendra's code is the code to put into your client.
    OIC, he wrote "server" --- it must have been a slip, he meant "client" :)

    1 Reply Last reply
    1
    • ODБOïO Offline
      ODБOïO Offline
      ODБOï
      wrote on last edited by
      #10

      That worked thank you very much

          void skReady(){      
              QByteArray buffer;
              buffer.resize(static_cast<int>(sk->pendingDatagramSize()));
              QHostAddress sender("127.0.0.1");
              quint16 senderPort=65111;
              qDebug()<<sk->readDatagram(buffer.data(), buffer.size(),&sender, &senderPort);          
          }
      
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      1
      • dheerendraD Offline
        dheerendraD Offline
        dheerendra
        Qt Champions 2022
        wrote on last edited by dheerendra
        #11

        Some confusion with where to place my code. Code has to be placed in App2(receiver) & not in the sender(App1)

        1. Client is writing data. So what you have in sender is fine.
        2. Receiver - You should place the code I suggested.

        Then tell me.

        Dheerendra
        @Community Service
        Certified Qt Specialist
        http://www.pthinks.com

        JonBJ 1 Reply Last reply
        2
        • dheerendraD dheerendra

          Some confusion with where to place my code. Code has to be placed in App2(receiver) & not in the sender(App1)

          1. Client is writing data. So what you have in sender is fine.
          2. Receiver - You should place the code I suggested.

          Then tell me.

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by JonB
          #12

          @dheerendra
          I'm only used to TCP. Never thought about terminology for UDP! I would have called the [UDP] server the side which is writing, not client, but maybe you know better than I :)
          https://stackoverflow.com/questions/9951875/who-is-the-server-and-who-is-the-client-in-udp

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          2
          • dheerendraD Offline
            dheerendraD Offline
            dheerendra
            Qt Champions 2022
            wrote on last edited by
            #13

            OK. Client & Server is only terminology.

            1. Server is the one which is waiting for connection.
            2. Client is the one which is initiating the connection.

            Once connection is established client/server terminology w.r.t data transfer is blurred as both will start transferring the data.

            Dheerendra
            @Community Service
            Certified Qt Specialist
            http://www.pthinks.com

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            • dheerendraD dheerendra

              You need to read the datagram. Try the following in server

              int main(int argc, char *argv[])
              {
                  QApplication a(argc, argv);
                  QUdpSocket sk;
                  sk.bind(QHostAddress::Any,65222);
              
                  QObject::connect(&sk,&QUdpSocket::readyRead,[&sk](){
                      qDebug() << Q_FUNC_INFO << endl;
                      sk.receiveDatagram();
                  });
              
              
                  return a.exec();
              }
              
              R Offline
              R Offline
              reshu
              wrote on last edited by
              #14

              @dheerendra i am using QT widget application to receive udp packets from another PC. my udp source is a labview VI. i am able to receive the data which i am sending .it is displaying in the debug window but not displaying in the user interface window.i tried textedit and listwidget. but not displaying anything. this is my first QT pgm. plz help.

              JonBJ 1 Reply Last reply
              0
              • R reshu

                @dheerendra i am using QT widget application to receive udp packets from another PC. my udp source is a labview VI. i am able to receive the data which i am sending .it is displaying in the debug window but not displaying in the user interface window.i tried textedit and listwidget. but not displaying anything. this is my first QT pgm. plz help.

                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by JonB
                #15

                @reshu
                Raise a new topic for this (and you will need to show some code beyond what you have asked here before anyone can help you). It has nothing to do with this QUdpSocket issue.

                R 1 Reply Last reply
                0
                • JonBJ JonB

                  @reshu
                  Raise a new topic for this (and you will need to show some code beyond what you have asked here before anyone can help you). It has nothing to do with this QUdpSocket issue.

                  R Offline
                  R Offline
                  reshu
                  wrote on last edited by
                  #16

                  @JonB i am not able to find the link for a new topic

                  JonBJ 1 Reply Last reply
                  0
                  • R reshu

                    @JonB i am not able to find the link for a new topic

                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by JonB
                    #17

                    @reshu
                    So when you go to https://forum.qt.io/category/10/general-and-desktop you do not see a big blue New Topic button at the top of the page?

                    You seemed to be able to raise https://forum.qt.io/topic/113963/udp-data-reception ?

                    R 1 Reply Last reply
                    2
                    • JonBJ JonB

                      @reshu
                      So when you go to https://forum.qt.io/category/10/general-and-desktop you do not see a big blue New Topic button at the top of the page?

                      You seemed to be able to raise https://forum.qt.io/topic/113963/udp-data-reception ?

                      R Offline
                      R Offline
                      reshu
                      wrote on last edited by
                      #18

                      @JonB yes

                      1 Reply Last reply
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