SendMessage in Windows/Linux

[AndrzejB]

In qt-solutions project is implement SendMessage by sockets:

bool QtLocalPeer::sendMessage(const QString &message, int timeout)
{
    if (!isClient())
        return false;

    QLocalSocket socket;
    bool connOk = false;
    for(int i = 0; i < 2; i++) {
        // Try twice, in case the other instance is just starting up
        socket.connectToServer(socketName);
        connOk = socket.waitForConnected(timeout/2);
        if (connOk || i)
            break;
        int ms = 250;
#if defined(Q_OS_WIN)
        Sleep(DWORD(ms));
#else
        struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
        nanosleep(&ts, NULL);
#endif
    }
    if (!connOk)
        return false;

    QByteArray uMsg(message.toUtf8());
    QDataStream ds(&socket);
    ds.writeBytes(uMsg.constData(), uMsg.size());
    bool res = socket.waitForBytesWritten(timeout);
    if (res) {
        res &= socket.waitForReadyRead(timeout);   // wait for ack
        if (res)
            res &= (socket.read(qstrlen(ack)) == ack);
    }
    return res;
}

How implement standard messages like Windows:

SendMessage(globalHWND, RegisterWindowMessage(IDENT), 0, 0)

Linux has not usual messages and must be used QLocalSocket ?