DBus connection

[Nitz]

Hi,

I'm trying to create two Qt applications and connect them through DBus system.

The first application, the receiver, has a slot named "reload". The other application, the sender, must call this slot.

The receiver

The main.cpp:

MainWindow is a class that inherits from QMainWindow.

#include <QApplication>
#include <QTextCodec>
#include <QDBusConnection>
 
#include "MainWindow.hpp"
#include "DBusManager.hpp"
 
int main(int argc, char *argv[]) {
	QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
	QApplication app(argc, argv);
 
	MainWindow *mainWindow = new MainWindow();
	new DBusManager(mainWindow, &app);
	QDBusConnection::sessionBus().registerObject("/", &app);
 
	mainWindow->show();
 
	return app.exec();
}

#include <QApplication>
#include <QTextCodec>
#include <QDBusConnection>

#include "MainWindow.hpp"
#include "DBusManager.hpp"

int main(int argc, char *argv[]) {
	QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
	QApplication app(argc, argv);

	MainWindow *mainWindow = new MainWindow();
	new DBusManager(mainWindow, &app);
	QDBusConnection::sessionBus().registerObject("/", &app);

	mainWindow->show();

	return app.exec();
}

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The DBusManager.hpp:

#ifndef COMPONENT_DBUSMANAGER
#define COMPONENT_DBUSMANAGER
 
#include <QDBusAbstractAdaptor>
#include <QApplication>
 
#include "MainWindow.hpp"
 
class DBusManager : public QDBusAbstractAdaptor {
	Q_OBJECT
	Q_CLASSINFO("D-Bus Interface", "org.simple-environment.sdesktop")
 
	private:
	MainWindow *mainWindow;
 
	public:
	DBusManager(MainWindow *mainWindow, QApplication *parent);
 
	public slots:
	Q_NOREPLY void reload();
};
 
#endif

#ifndef COMPONENT_DBUSMANAGER
#define COMPONENT_DBUSMANAGER

#include <QDBusAbstractAdaptor>
#include <QApplication>

#include "MainWindow.hpp"

class DBusManager : public QDBusAbstractAdaptor {
	Q_OBJECT
	Q_CLASSINFO("D-Bus Interface", "org.simple-environment.sdesktop")

	private:
	MainWindow *mainWindow;

	public:
	DBusManager(MainWindow *mainWindow, QApplication *parent);

	public slots:
	Q_NOREPLY void reload();
};

#endif

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The DBusManager.cpp:

#include "DBusManager.hpp"
 
/* Constructor */
 
DBusManager::DBusManager(MainWindow *mainWindow, QApplication *parent) : QDBusAbstractAdaptor(parent) {
	this->mainWindow = mainWindow;
}
 
/* Public slots */
 
void DBusManager::reload() {
	this->mainWindow->reload();
}

#include "DBusManager.hpp"

/* Constructor */

DBusManager::DBusManager(MainWindow *mainWindow, QApplication *parent) : QDBusAbstractAdaptor(parent) {
	this->mainWindow = mainWindow;
}

/* Public slots */

void DBusManager::reload() {
	this->mainWindow->reload();
}

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The sender

The sender, executes this code:

QDBusMessage message = QDBusMessage::createMethodCall("org.simple-environment.sdesktop", "/", "sdesktop", "reload");
QDBusConnection::sessionBus().call(message);

QDBusMessage message = QDBusMessage::createMethodCall("org.simple-environment.sdesktop", "/", "sdesktop", "reload");
QDBusConnection::sessionBus().call(message);

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I can compile both applications without problems, but when I execute them, the sender writes this through stderr:

process 14899: arguments to dbus_message_new_method_call() were incorrect, assertion "interface == NULL || _dbus_check_is_valid_interface (interface)" failed in file dbus-message.c line 1076.
This is normally a bug in some application using the D-Bus library.
QDBusConnection: error: could not send message to service "org.simple-environment.sdesktop" path "/" interface "sdesktop" member "reload"

What is wrong with this code?

[Nitz]

Ok, now it doesn't write the error through stderr. The problem was that I have specified bad dbus inteface at sender.

The new sender code:

QDBusMessage message = QDBusMessage::createMethodCall("org.simple-environment.sdesktop", "/", "", "reload");
QDBusConnection::sessionBus().call(message);

QDBusMessage message = QDBusMessage::createMethodCall("org.simple-environment.sdesktop", "/", "", "reload");
QDBusConnection::sessionBus().call(message);

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I run both applications but the receiver doesn't execute the "reload" slot

[Nitz]

The error is that I'm registering the object but not the service at receiver.

The solution is, at main.cpp:

#include <QApplication>
#include <QTextCodec>
#include <QDBusConnection>
 
#include "MainWindow.hpp"
#include "DBusManager.hpp"
 
int main(int argc, char *argv[]) {
	QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
	QApplication app(argc, argv);
 
	MainWindow *mainWindow = new MainWindow();
	new DBusManager(mainWindow, &app);
	QDBusConnection bus = QDBusConnection::sessionBus();
	bus.registerObject("/", &app);
	bus.registerService("org.simple-environment.sdesktop");
 
	mainWindow->show();
 
	return app.exec();
}

#include <QApplication>
#include <QTextCodec>
#include <QDBusConnection>

#include "MainWindow.hpp"
#include "DBusManager.hpp"

int main(int argc, char *argv[]) {
	QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
	QApplication app(argc, argv);

	MainWindow *mainWindow = new MainWindow();
	new DBusManager(mainWindow, &app);
	QDBusConnection bus = QDBusConnection::sessionBus();
	bus.registerObject("/", &app);
	bus.registerService("org.simple-environment.sdesktop");

	mainWindow->show();

	return app.exec();
}

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