Re: Issue on DLL Registration

"Alexander Nickolov" <>
Mon, 3 Jul 2006 11:06:25 -0700
Micrsoft ships marshaling support for its system interfaces
with the OS. ole32.dll and oleaut32.dll contain marshaling
code. For example the so called "universal" marshaler (e.g.
the IDispatch marshaler) resides in oleaut32.dll

Alexander Nickolov
Microsoft MVP [VC], MCSD

"Angela Yan" <> wrote in message

Hi Kim,

Thanks for pointing out that I can cross-post messages across newsgroup. I
did not realised that I can do that.

Hi Igor,

Thanks for the prompt reply. If both my DLL are actually implemented as
In-proc servers, am I correct to say that I do not need to merge the
proxy/stub into my DLL since I do not need marshalling, other than
multi-threading issues?

Just curious. So how does the OS managed the interface registration for
the system defined IDLs or those provided by Visual Studio Include? I
would think that these IDLs would be considered as shared common IDL as
well. In many cases, I also import a system defined IDL into my DLL, but I
do not see the same issue occuring.


"Igor Tandetnik" <> wrote in message

"Angela Yan" <> wrote in message

I have 2 different DLL files that shares a common IDL file. This
common IDL file contains some interfaces that is implemented by both
my DLL. When I register the 1st DLL file, it seems that some entries
are written into the HKCR/interface key.

When I register the 2nd DLL file, the same thing happens and the
entries are overwritten in the ProxyStubClsid32 to point to my 2nd

Are these automation interfaces marshalled via TLB, or are they custom
interfaces marshalled via proxy/stub DLL, and you are merging proxy/stub
code into the main DLL?

The problem is that you define the same interface in two different TLBs
(or provide the same marshalling code in two different DLLs - for
simplicity I'm going to assume the former for the rest of the
discussion). This is bad, for reasons you've discovered the hard way.

Take this common IDL file, and compile it into its own TLB. The two DLLs
should share this TLB file. If they don't have their own (non-shared)
interfaces, simply use MIDL-generated header or #import the shared TLB
into both projects. If they do have such interfaces, they would need
separate IDLs to describe them. In this case, don't forget to import the
shared IDL outside library section, and importlib the shared TLB inside.

When deploying either or both DLLs, don't forget to register the TLB too.
And be careful upon uninstall - you can only remove the TLB when all the
DLLs relying on it are removed. You may need some kind of reference
counting scheme.

Can anyone advise me on what might be wrong? I not sure why is there a
ProxyStubClsid32 key created for interface for my idea of interfaces
is that it is independent of the DLL that implements it

Interface is independent of the DLL that implements it. But it depends on
the DLL or TLB that provides marshalling support for it. This is why it's
a really good idea to have exactly one such DLL or TLB, ever.
With best wishes,
   Igor Tandetnik

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necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
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