How to communicate between two different app using SendMessage API?

[Anasuya2015]

Thanks for your help. I am facing issue in extracting the message. Code is as follows... APP1:

int WM_MYMSG = RegisterWindowMessage (L"MYMESSAGE");
HWND hw = FindWindow(NULL, L"Demo");
LPCTSTR strMsg = L"ClientDemo1";
//Send that message
::SendMessage(hw, WM_MYMSG, NULL, (LPARAM(LPCTSTR)strMsg);

APP2:

LRESULT CDemoDlg::OnMyMsg(WPARAM w, LPARAM l) {

MSG\* p = (MSG\*)l;
LPCTSTR str = (LPCTSTR)p->message;
MessageBox(str);// No message. But getting the alert while sending message. Need to extract the actual msg here.

return (LRESULT) 0;

}

Please let me know what changes is needed here by which it'll display "ClientDemo1" in msgbox.

[Lost User]

The LPARAM in your sending application is a Unicode string, so why are you casting it to a MSG pointer in the receiving app?

[Arthur V Ratz]

You can use COM automation, Named Pipes, TCP/IP Sockets or whatsoever by implementing your own protocol for interprocess communtication. :)

[Anasuya2015]

I am just finding the way to print the message. So you mean to say it is not needed and directly we can use lparam to print the message?

[Anasuya2015]

Here requirement is restrict to SendMessage() API. Anyway thanks for your answer. Can you send any sample code for Named Pipes implementation?

[Arthur V Ratz]

Using Pipes - MSDN Resource

[Lost User]

Anasuya2015 wrote:

So you mean to say ...

No, I am saying that whatever type you use in the LPARAM field in the sending app, you must use the same type in the receiver.

[Arthur V Ratz]

Also you can reuse SendMessage() API function with its regular list of arguments by implementing your own that encapsulates for example named pipes client mechanism. :)

[Serkan Onat]

You can use WM_COPYDATA[^] message with SendMessage API There is a linked example on MSDN topic as well

[David Crow]

Your casting is a bit unclear. It should probably be:

::SendMessage(hw, WM_MYMSG, NULL, (LPARAM) strMsg);
...
LPCTSTR str = (LPCTSTR) l;
MessageBox(str);

The process calling SendMessage() will likely be blocked by the second process since it will be waiting on the message box to be dismissed.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

[Maximilien]

:thumbsup: This is what we use and it works nicely

I'd rather be phishing!