timed polling of a database in a W2K service

i thought about starting a worker thread in Run() then making that a while(SERVICE_RUNNING) and then at the top of the while do a Sleep(300000) so each time round it waits 300 seconds before going round again.

oops that should be:

while(_Module.m_status = SERVICE_RUNNING){
   Sleep(300000);

   //do code here
}

Sounds reasonable, as long as you don't need to be doing anything else at the time (including message processing).

>>Can ATL system services support MFC class usage?

When you create the service, the AppWizard presents that as an option.  There is a "Support MFC" checkbox.

-- Dan

oops, I see that the Support MFC checkbox gets dimmed when you select the Service radio button.  Looking at my code, for a service that uses MFC, I see that I needed to add some headers to StdAfx.h:

#include <afxwin.h>         // MFC core and standard components
#include <afxext.h>         // MFC extensions

I also see that for some reason I have this in the InitInstance:

    afxContextIsDLL= FALSE;

Alas, I did not comment the reason for that code!
-- Dan

Why don't you just kick off a separate thread from the service in order to do the polling work - it could be as simple as

long WINAPI TimerThread ( LPVOID pv) {

DWORD dwWait = ( DWORD) pv,

for ( ;;) {

 Sleep ( dwWait);

 // do work here...
}
}

BTW, if you'd like something more sophisticated than the above, check out http://support.microsoft.com/support/kb/articles/q184/7/96.asp ("HOWTO: Use a Waitable Timer with an Asynchronous Procedure Call (Q184796)") and http://msdn.microsoft.com/library/en-us/dllproc/synchro_2bcj.asp ("Using Waitable Timer Objects")

Ah, drat as usual, excellent answer....but from completely different people.

Thanks guys.  Gimme a couple of days and I will dish out some points. :-)

MattC

one last thing :-)

below is the Run() method.
I have put '*****************' where i think my code should go, is this right???

void CServiceModule::Run()
{
    _Module.dwThreadID = GetCurrentThreadId();

    HRESULT hr = CoInitialize(NULL);
//  If you are running on NT 4.0 or higher you can use the following call
//  instead to make the EXE free threaded.
//  This means that calls come in on a random RPC thread
//  HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);

    _ASSERTE(SUCCEEDED(hr));

    // This provides a NULL DACL which will allow access to everyone.
    CSecurityDescriptor sd;
    sd.InitializeFromThreadToken();
    hr = CoInitializeSecurity(sd, -1, NULL, NULL,
        RPC_C_AUTHN_LEVEL_PKT, RPC_C_IMP_LEVEL_IMPERSONATE, NULL, EOAC_NONE, NULL);
    _ASSERTE(SUCCEEDED(hr));

    hr = _Module.RegisterClassObjects(CLSCTX_LOCAL_SERVER | CLSCTX_REMOTE_SERVER, REGCLS_MULTIPLEUSE);
    _ASSERTE(SUCCEEDED(hr));

    LogEvent(_T("Service started"));
    if (m_bService)
        SetServiceStatus(SERVICE_RUNNING);

    MSG msg;
    while (GetMessage(&msg, 0, 0, 0))
        DispatchMessage(&msg);

************************************** //<-- My Code here

    _Module.RevokeClassObjects();

    CoUninitialize();
}

Well, that depends on what your code is like :o)

:-)

see cookre's response at the top, I was gonna do something like that.
Matt

>>I was gonna do something like that

Uh, so your service has a UI?

no, but the hWnd argument can be NULL.

Yes, but the docs to 'SetTimer()' state:

"Remarks
An application can process WM_TIMER messages by including a WM_TIMER case statement in the window procedure or by specifying a TimerProc callback function when creating the timer. When you specify a TimerProc callback function, the default window procedure calls the callback function when it processes WM_TIMER. Therefore, you need to dispatch messages in the calling thread, even when you use TimerProc instead of processing WM_TIMER."

If you don't have any UI, there will be no msg processing/dispatching...

MSG msg;
while (GetMessage(&msg, 0, 0, 0))
DispatchMessage(&msg);

i thought that's what this section did?

Ooops :o)

phew, i thought i was gonna have to rewrite a whole load of documentation there :0)

Documentation?
You mean there's more to this job than coding?

>>******************************* //<-- My Code here

I think you would want to start the timer above there, then handle it in the TimerProc, outside of the loop.

-- Dan