send message from service to user mode application in vista/windows7

Question

I want to send a message from windows service to user mode application, I know its not allowed in Vista and above OS.

is there any special window message for this? or any other alternate?

I want to play sound on a specific operation, service should inform to application for play the sound on some specific events.  

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मनोज कुमार जांगिड NATHCORP

Answer 1

A service and a user mode application can communicate by using a named pipe.  See CreateNamedPipe()

Answer 2

You can use a named event. The user mode application can wait for the event to be signaled. The name of the event must be prefixed with Global\.

Look at the documentation for CreateEvent.

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«_Superman_»
Microsoft MVP (Visual C++)

Answer 3

Yes its worked

Thank you

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मनोज कुमार जांगिड NATHCORP

Answer 4

When I call CreateFile() second time I am getting error massege 231 [ERROR_PIPE_BUSY - All pipe instances are busy]

I am sending message from service application to client application.
Named pipe is create in service application and client application is receving data from service application.

Service Application Functions

bool InitServer()
{
	try
	{
		SECURITY_ATTRIBUTES sa;
		sa.lpSecurityDescriptor = (PSECURITY_DESCRIPTOR)malloc(SECURITY_DESCRIPTOR_MIN_LENGTH);
		if (!InitializeSecurityDescriptor(sa.lpSecurityDescriptor, SECURITY_DESCRIPTOR_REVISION))
		{
			strLog.Format(_T("ERROR(Line:%d):%s"),__LINE__, GetErrorString(::GetLastError()));
			AddToLog(strTitle,strLog);
		}
		if (!SetSecurityDescriptorDacl(sa.lpSecurityDescriptor, TRUE, (PACL)0, FALSE))
		{
			strLog.Format(_T("ERROR(Line:%d):%s"),__LINE__, GetErrorString(::GetLastError()));
			AddToLog(strTitle,strLog);
		}
		sa.nLength = sizeof sa;
		sa.bInheritHandle = TRUE;

		union maxSize
		{
			UINT _1;
		};

		m_hServer = ::CreateNamedPipe(	m_strPipeName,
			PIPE_ACCESS_OUTBOUND, 
			PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT, 
			PIPE_UNLIMITED_INSTANCES, 
			sizeof maxSize,	
			sizeof maxSize, 
			NMPWAIT_USE_DEFAULT_WAIT, 
			&sa);

		if (m_hServer == INVALID_HANDLE_VALUE)
		{
		return false;
		}
	}
	catch(...)
	{
		return false;
	}
	return true;
}


bool SendData(UINT uID)
{
	DWORD dwRead = 0;
	if (!(WriteFile(m_hServer, (LPVOID)&uID, sizeof UINT, &dwRead, 0)))
	{
	return false;
	}
::Sleep(0);
return true;
}

Client Application

bool	InitClient()
{
	DWORD dwError = 0;
	while (true) 
	{ 
		m_hClient = ::CreateFile(	m_strPipeName, 
					GENERIC_READ, 
					0, 
					0, 
					OPEN_EXISTING, 
					0, 
					0);
		if (m_hClient != INVALID_HANDLE_VALUE)
		{
			break;
		}
		if (GetLastError() != ERROR_PIPE_BUSY) 
		{
			return false;
		}
		if (!WaitNamedPipe(m_strPipeName, 10000)) 
		{ 
			return false;
		} 
	}
	return true;
}

Above client code working when I am connecting first time.
After restart client application I am getting above mentioned error.

WaitNamedPipe -  this gives [Error Number - 121 The semaphore timeout period has expired]

any clue to solve this?

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मनोज कुमार जांगिड NATHCORP

Answer 5

>> After restart client application I am getting above mentioned error

Does the first client close the pipe (with CloseHandle)?

If you create only one pipe in the server it can connect to only one client at a time.

Answer 6

Yes client application handle closed with CloseHandle()
::CloseHandle(m_hClient);
  m_hClient = NULL;

I have only one client at a time - but this client can be restart multiple times

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मनोज कुमार जांगिड NATHCORP