How to communicate Qt Process with non-qt process

[nrabara]

Hi,

How to Communicate 2 different process running on the same host using Dbus?(ARM in my case).

I have few confusion regarding use and implementation of qt Dbus. I am using Qt for Embedded Linux 4.4.

My scenario,
I am developing one device having GUI interface which works as SLAVE and connected to MASTER. SLAVE's main process will communicate with MASTER for sending and receiving messages.

I want to display this messages coming for MASTER.

Process 1:- Main Process take cares of hardware drivers and send and receive messages from MASTER (distributed architecture). e.g.:- ./MainProcess
Process 2:- Separate Qt process for GUI Display. e.g.:- ./QtProcess

Can anybody guide me how to solve this problem?
Immediate response would be highly appreciable.

Thanks in Advance,
Nirav

[wysota]

What is the exact problem? Have you managed to connect to the session bus with both applications?

[nrabara]

I don't know how to create session between two different process. Would you please explain me?

[wysota]

Have you seen the dbus examples that come with Qt?

[nrabara]

Yes, I have seen that Dbus examples. but these examples are only for Qt applications(I mean to communicate to different Qt application).

As per my knowledge(might be wrong also)I need to use QCopChannel to Communicate Qt and non-Qt Application.

there is no examples for QCopChannel.

waiting for feedback, your suggestion would be helpful for me.

[nrabara]

Hi,

I would be really thankful if anybody tell me how to communicate qt Process with not non-Qt process.

I have read DBus and QCopChannel but still not clear about it.

Your immediate response would be highly appreciable.

[wysota]

So you want to use D-Bus or QCopChannel? D-BUS can be used to communicate between Qt and non-Qt application. With QCopChannel I think this is not possible.

[wysota]

Please don't start multiple threads on the same subject - threads merged.

[QbelcorT]

Hi,
You can use QCopChannel. You need a Qt App object though in your non-gui process.
1) In your gui application, start it as such QApplication app(argc,argv, QApplication::GuiServer);
2) then in your non-gui app you need this QApplication app(argc,argv, QApplication::GuiClient);
3) Get your server app (gui application) to start the client app. Using QProcess::start("clientapp"). Start it once the the server app has already entered the event loop. i.e for example when the window is shown.
4)You need to declare a QCopChannel object in your gui app, and receive the events from your client process. In my case I have a channel called "gpio", I declare the QCopchannel("gpio"). This registers the channel. Then whenever your non-gui app sends events to ("gpio") channel your gui app will receive them. You have to implement the receive event in your gui-app.
This is a brief explaination but it should set you in the right direction.

Then you need to send the Server app (your Qt app) a message. This is a helper function you don't need it.

int sendEventWData(char *string, unsigned char *buf, int size)
{
//	QByteArray::fromRawData((const char *)buf,size); 
	sendQCopEvent(GPIO,string,QByteArray::fromRawData((const char *)buf,size));
	return 0;
}
 
int sendQCopEvent( char *channel, char *string, const QByteArray &data)
{ 
	if(QCopChannel::isRegistered(channel))
	{
		QCopChannel::send(channel, string, data);
		QCopChannel::flush();
		return 0;
	}
	return -1;
}

int sendEventWData(char *string, unsigned char *buf, int size)
{
//	QByteArray::fromRawData((const char *)buf,size); 
	sendQCopEvent(GPIO,string,QByteArray::fromRawData((const char *)buf,size));
	return 0;
}

int sendQCopEvent( char *channel, char *string, const QByteArray &data)
{ 
	if(QCopChannel::isRegistered(channel))
	{
		QCopChannel::send(channel, string, data);
		QCopChannel::flush();
		return 0;
	}
	return -1;
}

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[webquinty]

Hello,

I use Share Memory to comunicate varibales between nonQT and QT process