communication between server client in qt dbus

Question

I'm new to QT programming. I'm trying to communicate between two qt applications using DBUS, I've been able to create a interface adapter and communicate as follows,

• Registering service on the server application.
• connecting to the interface object on the client side and calling the methods in the server.

My question is, if the server has to send back messages to client, should client create a new interface or is there any other way this can be done?

Answer 1

D-Bus has signals (not Qt signals, but they are mapped to signals if used with QDBusAbstractAdaptor).

This example shows a server D-Bus object that can send notifications to the clients:

class MainApplicationAdaptor: public QDBusAbstractAdaptor
{
    Q_OBJECT
    Q_CLASSINFO("D-Bus Interface", "org.kde.DBus.MainApplication")
    Q_PROPERTY(QString caption READ caption WRITE setCaption)
    Q_PROPERTY(QString organizationName READ organizationName)
    Q_PROPERTY(QString organizationDomain READ organizationDomain)

    ...

signals:
    void aboutToQuit();
    void mainWindowHasFocus();
};

Interface definition:

interface org.kde.DBus.MainApplication
{
    property readwrite STRING caption
    property read STRING organizationName
    property read STRING organizationDomain

    method quit() annotation("org.freedesktop.DBus.Method.NoReply", "true")
    method reparseConfiguration()
    method mainWindowObject(out STRING)
    method disableSessionManagement(in BOOLEAN enable)

    signal aboutToQuit()
    signal mainWindowHasFocus()
}