Need help with events in COM in pure C++!

Question

Hello, guys! Very important question:

Please, look at my project (300Kb). I can`t use MFC/ATL, pure C++ only.

I have COM library (niapi.dll), but no sources/headers available, dll only.

There is class for connecting to server (NiApi::SrvrSession), class has login event handler (NiApi::SrvrSession::OnLogin).

I used

#import "NiApi.dll"

to generate wrappers/information,

then

ISrvrSessionPtr session(L"NiApi.SrvrSession");

to create object, then trying

session->put_OnLogin();

to assign events, but there is no one put_On or such member.

niapi.tlh have _ISrvrSessionEvents struct inside, but it have no relations with SrvrSession.

I need to use events from NiApi::SrvrSession for handling connection status.

Please help or my boss kill me! (sorry for broken english, I read better than speak;)

Answer 1

The put_ prefix is the default prefix for the raw interface (customizable via the raw_property_prefixes attribute). Since you are not using the raw interface, use session->OnLogin=... instead.

For event handling see ADO Events Model Example (VC++)

Answer 2

COM events are handled via connection points. You need to write your own COM object that implements whichever event interface you are interested in. Then you need to connect it to the COM object that fires the events. First you QI the COM object for its IConnectionPointContainer, then find the corresponding connection point of the GUID of the event interface. The you call its Advise method to connect it to your event sink.

class CSrvrSessionEvents: public _ISrvrSessionEvents
{
public:
    HRESULT OnLogin(long LoginResult)
    {
        // do something
        return S_OK;
    }
    // implement rest of _ISrvrSessionEvents
};

ISrvrSession* pSrvrSession = ...; // get ISrvrSession from somewhere
_ISrvrSessionEvents* pSrvrSessionEvents = new CSrvrSessionEvents();
IConnectionPointContainer* pCPC = NULL;
pSrvrSession->QueryInterface(IID_IConnectionPointContainer, &pCPC);
IConnectionPoint* pCP = NULL;
pCPC->FindConnectionPoint(__uuidof(_ISrvrSessionEvents), &pCP);
DWORD dwCookie = 0;
pCP->Advise(pSrvrSessionEvents, &dwCookie);
pSrvrSession->Connect(); // I assume this fires some events
pCP->Unadvise(dwCookie);

Answer 3

What is really necessary, is to carefully read http://www.codeproject.com/kb/com/TEventHandler.aspx.

All explainrd here.

Thanks to all for help!