How to access sub object in CANoe COM Server Interface

Question

I have one big and difficult to understand problem with COM Server. I’m trying write client application to CANoe (application by Vector). They gave CANoe.tlb, CANoe.h and CANoe_i.cpp files but I use only CANoe.tlb via #import. All examples are in Visual Basic and I’m trying to write it in VC++ (console application). The problem is with inheritance. I.e. in help they wrote, that main object is Application and access to all methods, object events etc. is possible only via this object. All examples in Visual Basic are also simple, i.e:

Dim gCanApp As CANalyzer.Application
Set gCanApp = New Application
gCanApp.Open ("C:\Program Files\CANalyzer\Demo_CL\motbus.cfg")
gCanApp.CAPL.Compile
gCanApp.Measurement.Start

I’m sure that I’m making mistake but I have no idea where. In simply words I don’t have access to subobjects, their methods etc. I have only access to Application’s methods. For example I’d like to call method Start from Measurement object in this way: pApp->Measurement->Start() but it is impossible.

My source code:

#import "CANoe.tlb" //importing CANoe type library
#include "stdafx.h"
#include <atlbase.h> //COM Server methods
#include <iostream>

using namespace CANoe;
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
    /*This part is working perfectly: */
    CComPtr<IApplication> pApp = NULL;
    CComPtr<IMeasurement> measure = NULL;
    CComPtr<ICAPL> capl = NULL;
    CLSID clsid;
    IID iid;
    HRESULT result;

    /* Initialization COM library: */
    if (FAILED(CoInitialize(NULL))) 
    {
        cerr << "Initialization COM Library error" << endl;
        system("pause");
        return 1;
    }
    if((result = CLSIDFromProgID(L"CANoe.Application", &clsid)) != S_OK) 
    {
        cerr << "Problem with opening application" << endl;
        system("pause");
        return 2;
    }
    result = pApp.CoCreateInstance(clsid);  //Opening CANoe Application
    if(result != S_OK)
                cout << "pApp fault" << endl;

    pApp->Open(L"C:\\test\\test.cfg", FALSE, TRUE); //Opening test.cfg file
    /****************End of good part**********************/

    //pApp->Measurement->Start();//I'd like to use it in this way - compiler error: error C2039: 'Start' : is not a member of 'IDispatch'

    pApp->get_Measurement((IDispatch**)&measure);
    measure->Start();//Unhandled exception at 0x7711d78c in canoe.exe: 0xC0000005: Access violation writing location 0x7711d78c.
    CoUninitialize(); //Uninitialization COM Library
}

I attache CANoe COM Server files (it is legal from free Demo version): http://www.sendspace.com/file/5pgcou

P.S. Using COM Server is new for me so sorry for eventually stupid mistake. I was searching for any helpful information but I didn't find anything about using this COM Interface.

Answer 1

Try to change your code:

CComQIPtr<IMeasurement> measure;
CComPtr<IDispatch> measureDisp;

pApp->get_Measurement(&measureDisp);
measure = measureDisp;
measure->Start();

Also don't forget to check results of called methods.