I want to send messages between 2 windows-applications. What must I do?

Both applications are written in C++. The first application must send a message and the other application must react if the message is sent. Any help is appreciated.

[Michael Owen]

One way to do it is to use the FindWindow() function and post a mutually defined message to the other app.

[Serguei Batchila]

Here is the sample (not the only way, I guess, but I would use it)

// 1. In your application-sender:
UINT Message2Send = ::RegisterWindowMessage("STR_CoolMessage");

// 2. In your application - receiver:
UINT Message2Receive = ::RegisterWindowMessage("STR_CoolMessage");

// Note: the trick is to register messages using EXACTLY THE SAME
// string in both applications: Windows will return THE SAME value.

// 3. In your application-sender:
::SendMessage(HWND_BROADCAST, Message2Send, (WPARAM)0, (LPARAM)0);
// This call will send the message for all top-level windows in the system, see Help

// 4. The rest is to catch and handle the message in application - receiver:
// In you MainFrame declare function-handler
afx_msg LRESULT OnCoolMessage(WPARAM WParam, LPARAM LParam);

// In message map of your MainFrame add this entry
ON_REGISTERED_MESSAGE(Message2Receive, OnCoolMessage)

// And add implementation:
LRESULT CMainFrame::OnCoolMessage(WPARAM WParam, LPARAM LParam)
{
AfxMessageBox("COOL!");
return (LRESULT)0;
}

[shankar]

Hi,

Use the user defined messages.
In the first app define a message with WM_USER + ...
i.e #define WM_MYMSG WM_USER+1
Same in the second app.

Handle the messages with appropriate functions.

Call the SendMessage with ur own MessageHandler
i.e SendMessage(WM_MYMSG, .......)

Hope this helps
Shankar

[ktpark]

Hi. I had tested your code. But did not work between 2 app. What's the prolem ?

Regards

ktpark

[Sadhu]

Check out this link

http://codeguru.developer.com/bbs/wt/showpost.pl?Board=vc&Number=59995&page=3&view=collapsed&sb=5

sadhu

[Serguei Batchila]

Hi
I don't know why, but SendMessage(HWND_BROADCAST, ... ) really doesnt work. You can use PostMessage instead (parameters are the same). I works, I've tested it.

[ktpark]

Hi. Thanks for your response. I got it this problem. See the link below.
http://codeguru.developer.com/bbs/wt/showpost.pl?Board=vc&Number=61261&page=0&view=expanded&mode=threaded&sb=5&category=

Thanks for all comments

Best regards

ktpark