//! [0]
class MyObject: public QObject,
                protected QDBusContext
{
    Q_OBJECT
    QDBusConnection conn;
    QDBusMessage msg;

...

protected slots:
    void process();
public slots:
    void methodWithError();
    QString methodWithDelayedReply();
};

void MyObject::methodWithError()
{
    sendErrorReply(QDBusError::NotSupported,
                   "The method call 'methodWithError()' is not supported");
}

QString MyObject::methodWithDelayedReply()
{
    conn = connection();
    msg = message();
    setDelayedReply(true);
    QMetaObject::invokeMethod(this, "process", Qt::QueuedConnection);
    return QString();
}
//! [0]