Fix problem with QTCPSocket?

QTDavid

Hello,

I am having a bit of problem in creating a TCP client/server.
The first message it sends, when the new connection is first established, arrives correctly to the client. However all the messages that I would like to send after are not read correctly (I think that the sending code).
I followed the fortune examples, but I could not get it to work.
Here's come of my code:

@// server sending code

void MainWindow::sendMessage()
{
// what is the next pending connection, that is the socket we want to talk to
ui->textBrowser->append("Sending message...");

if (!ui->messageInput->text().isEmpty()) {
    // there is message in the input line
    messageToSend = ui->messageInput->text();

} else {
    // otherwise use the predefined message
    messageToSend = "Predefined message";
}

QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_4_0);

out << (quint16)0;
out << messageToSend;
out.device()->seek(0);
out << (quint16)(block.size() - sizeof(quint16));

clientConnection->write(block);         // send the block of data

ui->textBrowser->append("Sent: " + messageToSend);

}
@

@// client receiving code

QDataStream in(newSocket);
in.setVersion(QDataStream::Qt_4_0);

if (blockSize == 0) {
    qDebug() << "1";

    if (newSocket->bytesAvailable() < (int)sizeof(quint16))
        return;

    in >> blockSize;
    qDebug() << blockSize << "  " << newSocket->bytesAvailable();
}

if (newSocket->bytesAvailable() < blockSize) {
    qDebug() << "2";
    return;

}

QString nextMessage;
in >> nextMessage;
qDebug() << nextMessage;

@

nextMessage should be the message that was sent by the server.
I think that the client is not reading correctly.

Can anyone help me out?
Thanks

QTDavid

Ah, sorry for repost.
Just assume that the connection between client and server is successful.
I am using something like this:

In client:
@
connect(newSocket, SIGNAL(readyRead()), this, SLOT(readMessage()));
@

In server:
@
connect(newServer, SIGNAL(newConnection()), this, SLOT(sendMessage()));
@

Code_ReaQtor

newConnection() "triggers" only when there are new sockets who want to connect to the sever. apparently, it is already connected so newConnection() will not be called again.

If I remember clearly, that example follows these steps:

client connects

server accepts

server sends message

...and server disconnects client (or client disconnects itself?)

..then return to step 1.

Try disconnecting the client t the end of "sendMessage()" function.

If your goal is to have the server only to send messages, this is OK. But if your goal is a "bidirectional" server-client connection, I don't recommend it.

QTDavid

But my thing is that I want to keep the connection open, I don't want to close it every time a message it's sent.
Is it possible to do that?

Code_ReaQtor

[quote author="QTDavid" date="1358337004"]But my thing is that I want to keep the connection open, I don't want to close it every time a message it's sent.
Is it possible to do that?[/quote]

Yes, it is possible. Might be better if you have the code to revise.