QCopChannel Class Reference
[QtGui module]

Detailed Description

The QCopChannel class provides communication capabilities between clients in Qt for Embedded Linux.

Note that this class is only available in Qt for Embedded Linux.

The Qt COmmunication Protocol (QCOP) is a many-to-many protocol for transferring messages across registered channels. A channel is registered by name, and anyone who wants to can listen to the channel as well as send messages through it. The QCOP protocol allows clients to communicate both within the same address space and between different processes.

To send messages to a given channel, QCopChannel provides the static send() function. Using this function alone, the messages are queued until Qt re-enters the event loop. To immediately flush all queued messages to the registered listeners, call the static flush() function.

To listen to the traffic on a given channel, you typically instantiate a QCopChannel object for the given channel and connect to its received() signal that is emitted whenever there is incoming data. Use the static isRegistered() function to query the server for the existence of a given channel. QCopChannel provides the channel() function returning the name of this QCopChannel object's channel.

In additon, QCopChannel provides the virtual receive() function that can be reimplemented to filter the incoming messages and data. The default implementation simply emits the received() signal.

See also QWSServer, QWSClient, and Qt for Embedded Linux Architecture.

Member Function Documentation

 void MyClass::receive(const QString &message, const QByteArray &data)
 {
     QDataStream in(data);
     if (message == "execute(QString,QString)") {
         QString cmd;
         QString arg;
         in >> cmd >> arg;
         ...
     } else if (message == "delete(QString)") {
         QString fileName;
         in >> fileName;
         ...
     } else {
         ...
     }
 }

 QByteArray data;
 QDataStream out(&data, QIODevice::WriteOnly);
 out << QString("cat") << QString("file.txt");
 QCopChannel::send("System/Shell", "execute(QString,QString)", data);