COM

Do you set the DBSTATUS_S_ISNULL in the status field for the accessor in your custom OLEDB provider??? I guess that is why VB does not cosider it as NULL properly.

Thanks for your concern, but I asked the author of those VB components to recompile his works. Don't understand why, but after recompilation, I could view all the IDL's with OLE Viewer and #import them without any problems. As long as it works - I am happy.

Sure. 1) and 2) will call same function implementation. I don't quite catch your intention. This is just simple class or struct inhertance. This is nothing to do with COM as I understand. What do you want to do? Regards, Ryan

Thanks Felix. This will definitely raise me from ATL HELL. The problem with those #import's - lack of documentation and examples. I only understood no_namespace, rename_namespace, rename and named_guids (the easiest ones). All other flags had been complete mystery. Kirill.

Sorry guys, fixed it now. I was using memset and including memory.h in one of my classes which seemed to cause it. Although I could comment out the memset and include statements, build it, uncomment them and build again and then it'd work. Although gives a warning: LINK : warning LNK4089: all references to "MSVCIRT.dll" discarded by /OPT:REF Which is good I guess. Can't see any options or flags that may have changed to cause this though.

That's where COM apartment may help. Your ActiveX control is apartment threaded, which means that all calls to that object always must be executed on the same thread. Looks like your client also apartment threaded, but probably when you use your ActiveX object on other thread you didn't marhsall you interface pointer (CoMarshalInterface or CoMarshalInterThread..). One possible fix, that won't require much changes, is to put all client threads in free threaded apartment (each thread should calls CoInitialiseEx(NULL, COINIT_MULTITHREADED)). There will be slight perfomance hit, since all the calls to your object will be marshalled. If it's not acceptable ( or the client must be apartment threaded), than you'll need to use CoMarshal../Unmarshall or Global interface table (see IGlobalInterfaceTable, CLSID_StdGlobalInterfaceTable) to marshal interface pointer between apartments. In this case the calls from apartment that created object won't be marshalled. Hope this helps. Edward.

In the event that the CLSID of the CoClass object is not known, you can: - use the COM category manager (ICatInformation) and enumerate the objects' CLSIDs at runtime - do category management under your own registry key(s), basically you store the list of COM object CLSIDs and you call CoCreateInstance() on those CLSID and get your interface using QueryInterface() after that

first rid yourself of the [50]'s cause you don't need them. the string attribute tells MIDL to look for the null terminator and it does size calculations on its own. Next get rid of the typedef. MIDL doesn't need it. just use struct PATIENT_INFO { [string] wchar_t wszPatientID; [string] wchar_t wszLastName; }; Hope this helps ya out. Joseph Dempsey jdempsey@cox.rr.com Joseph.Dempsey@thermobio.com "Software Engineering is a race between the programmers, trying to make bigger and better fool-proof software, and the universe trying to make bigger fools. So far the Universe in winning." --anonymous

Hi Yamini :rose: The component u r using in VC++, i suppose have u tried L"xyz" in this fashion.if not then try it,possibly u will get the answer.Or try in this way:- CString str; str="ABC"; str.SysAllocString(); Then pass this instead of BSTR argument. This may solve the problem. Bye