Discussion:
Bizarre COM interop problem (using OPC automation wrapper)
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j***@gmail.com
2015-02-09 09:15:26 UTC
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I have had the same problem, while devloping with .net2. After switching to .net4 it worksy very well. I can not explain it :(
d***@gmail.com
2015-09-08 14:29:37 UTC
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hello i'm just a users MS.Net (newbie), and then i also still develop the OPC, did you help to explain about Classic COM Clients different with COM .Net? why?.
if i see the envrnmt from .NET very complete.

Regards
Dian Muhammad Adam

On Wednesday, June 5, 2002 at 11:42:01 AM UTC-7, Andy DeMaurice [MS] wrote:
> The problem with get_OPCGroups doesn't have anything to do with the one or
> zero based array problem.
>
> The opcdaauto.dll behaves different from what its type library says. The
> type library indicates that there are three different coclasses: the
> server, the groups, and the group. It indicates that when you call
> get_OPCGroups you get a Groups object.
>
> You don't.
>
> The server object and the Groups object are one and the same. When you
> call get_OPCGroups you just get a different interface pointer to the same
> object (the server object). This does not pose a problem with classic COM
> clients (VB6, C++) but it causes a big problem with .NET.
>
> NET checks the COM identity rule of the interface pointer that it gets
> back from get_OPCGroups, and realizes that it is the same object as the
> server object. Since it already has a RCW for the server object, it just
> uses the same wrapper for the new pointer.
>
>
> Andy DeMaurice
> Microsoft Developer Support
>
> This posting is provided "AS IS" with no warranties, and confers no rights.
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