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Use of <QtConcurrentRun> - Asynchronous Run on a Network class

  • Hi all,

    I have been googling the web for a while and I cannot find the answer, even w/ Qt example.

    Here is the problem:

    • I want to communicate w/ an embedded system that gives me an answer each time I send a message

    • I got high level network class NetworkInterface that (de)connect to the network, send and receive message (those methods are virtual) from serial port (using qtsp) to the embedded module.

    So I send 1 unique message with this method
    @serialClass->sendMessage((QString) my_message);@

    and I got the answer with a connect
    @QObject::connect(serialClass, SIGNAL(readyRead()), this, SLOT(slotReceiveData()), Qt::DirectConnection);@

    That part work well!


    Now if I want to send multiple questions, I stupidly use a while loop on my SQL table:


    As we expected, the loop is too fast and as to be done to start readyRead() signal. So I send every message and only get the first answer!

    So what I want to acheive is :

    Send the message

    Stop the loop until I got the embedded answer

    display the answer

    continu the loop

    That is the reason why I need to use real time operating system by waiting the answer from my embedded module OR stop the while loop for several second and then reactive it!

    4 solutions:

    Using thread ? but my both functions send and received are on the same class and moreover are virtual

    Using semaphore or mutex ?

    Creating a kind of RTOS sytem by doing one unique action each sec (so the system got an action table to realized (beurk !))

    Using QtConcurrentRun ? but my both functions send and received still in the same class and moreover are virtual and does not accept that I declare

    @QFuture<void> future = QtConcurrent::run(sendMessage, message);@
    error: no matching function for call to 'run(<unresolved overloaded function type>, const QString&)'

  • What u need is to build a Soap Server / Client solution no ?

  • I never heard about soap before! Any way to fix it easily ?

  • SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks.

    Qt have a strong partnership KDAB. You can have more info and examples on this link:

  • thx u bjanuario, by the way i m scared that it is not possible to use SOAP in my project, and I am sure it ll be possible to fix it using a different method ?

  • You can use soap for that, but you can also use QCOP class.
    I never worked with that, but I have some friends did it.
    You can check this link:

    Hope this can clarify you.
    Kind Regard

  • Ok problem solve.

    In this king of trouble, the best way to fix it, is to code that way :

    • create a FIFO (w/ a vector<obejct> for example) between your GUI and network interface
    • send only one message from the fifo and pop this message.

    The reception is usually done with a connect like :
    @QObject::connect(ClassNetwork, SIGNAL(readyRead()), this, SLOT(my_slot());@

    In that case, it is easy to get the received message, and so, send the next FIFO message and pop it, etc.

    Finally use a thread for the time out :)

    Hope It will help u !

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