what is the best way to make a network app? multi-thread...heart-beating...

opengpu2

what is the best way to make a network app? multi-thread...heart-beating...
i seems that there is no msg loop explicitly in main()...
i want to read data from the server in a loop.

is there any good example to create a thread and do this network thing(eg. heart-beating)?

thank you!

sneubert

Hi opengpu2,
if you´re not tied to Qt have a look at boost::asio.

mcosta

@opengpu2 said:

what is the best way to make a network app? multi-thread...heart-beating...

The right answer is: "There isn't the BEST way". It depends of your application feauters and requirements

i seems that there is no msg loop explicitly in main()...
i want to read data from the server in a loop.

Qt usually prefers the Asynchronous approach but you can read from a socket with blocking API like QUdpSocket::readDatagram()

is there any good example to create a thread and do this network thing(eg. heart-beating)?

thank you!

SysTech

Alternatively you can do threads and timers to sort of make your own loop.

opengpu2

yes, i don't want to use boost, and i want to use Qt.
what is the API or demo that shows how to create a thread in Qt?
and where should i create the timer? in the main thread or the new thread?
and how to write the slot...thank you.
and i think this timer method is sort of heart-beating, right?

mcosta

Hi,

as I said before you don't necessarily need a Thread for this work; Do you need to receive data from server or request data to the server?

Receive Data (f.i. using a UDP socket)

void ServerConnection::initSocket()
{
    udpSocket = new QUdpSocket(this);
    udpSocket->bind(QHostAddress::LocalHost, 7755);

    connect(udpSocket, SIGNAL(readyRead()),
            this, SLOT(readPendingDatagrams()));
}

void ServerConnection::readPendingDatagrams()
{
    while (udpSocket->hasPendingDatagrams()) {
        QByteArray datagram;
        datagram.resize(udpSocket->pendingDatagramSize());
        QHostAddress sender;
        quint16 senderPort;

        udpSocket->readDatagram(datagram.data(), datagram.size(), &sender, &senderPort);

        processTheDatagram(datagram);
    }
}

Request Data

myTimer = new QTimer(this);
connect(myTimer, &QTimer::timeout, this, &MyClass::requestData);

void MyClass::requestData()
{
   // Request data to the server
}

opengpu2

thank you very much.
i dont use QUdpSocket..i use my own network classes.
right now i Tick the network io in the new thread. that's why i want to readData in msg loop, or heart-beating...

maybe Tick the network io in the new thread, and use a timer as heart-beating in the main thread to readData() is a good method?

mcosta

Hi,

if you don't need to use high-speed communication or a lot of data you can do the whole processing (tick and readData) without threads

opengpu2

u mean i can put all this in the Times' slot()?

opengpu2

and if i want high-speed communication or a lot of data, what should i do ?
it seems that u prefer not to create a new thread...why ? what is the disadvantage?

mcosta

Hi,

I think you should use something only if you really need it.
Qt is designed to work in asynchronous mode so you can handle multiple source of data in a single-thread application.

You should move to multi-threading when you need the handle long time processing or when you need to non block who's sending you data.

opengpu2

thank you
i need the network io always Tick().
and i also need readData from the server all the time...eg. in a msg loop in windows..
but there seems no msg loop in Qt, so i wanted to use a timer as heart-beat to put readData in it.

mcosta

Hi,

do you need to read data only at tick?? In that case use the timeout signal to read data

connect (timer, &QTimer::timeout, this, &MyClass::readData);

void MyClass::readData() 
{
   // Read from server
}

opengpu2

yes,
in addition, i want to put the network io Tick into a new thread.
the readData() in the timeout slot.

opengpu2

and what is the normal way to create a new thread? (i want sth like ::CreateThread in window)