can 32bit and 64bit .net COM have same GUID

Question

can 32bit and 64bit .net COM have same GUID

Whelan, Ken (Baker Hughes Contractor) 20

Have a C# created COM object originally implemented for 32bit. Now have a need for it in 64bit for additional applications. Can the 64bit have the same GUID as the 32bit version. They will reside on the same machine

David Lowndes 2,640 Reputation points MVP

2023-07-12T20:51:14.8833333+00:00

I believe so - the 32-bit registry (on a 64-bit OS) is separated by Wow6432Node branches.

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David Lowndes 2,640 Reputation points MVP

2023-07-12T20:51:14.8833333+00:00

I believe so - the 32-bit registry (on a 64-bit OS) is separated by Wow6432Node branches.

Answer 1

Anonymous

Hi @Whelan, Ken (Baker Hughes Contractor) , Welcome to Microsoft Q&A.

As David Lowndes mentioned, 32-bit and 64-bit COM components are located differently in the registry because they are registered in different Windows registry paths. This means that when registering a COM component, it needs to be correctly registered in the 32-bit or 64-bit registry path so that it can be used correctly in the corresponding environment. From this consideration, you can use the same GUID.

In .NET COM (Component Object Model), GUID (Globally Unique Identifier) is an identifier used to uniquely identify a component. From this definition, I wouldn't recommend you to use the same guid.

Did you know that 64-bit programs can also use 32-bit com? Check out DLL Surrogates.

Best Regards,

Jiale

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RLWA32 49,541 Reputation points

2023-07-13T14:10:01.4533333+00:00

It should be noted that DLL Surrogates run as out-of-process servers. Depending on the Questioner's objectives this may be a relevant consideration.
RLWA32 49,541 Reputation points

2023-07-13T16:21:01.4966667+00:00

I can't see a reason why a 64-bit COM object that implements the same interfaces, methods and properties as its 32-bit predecessor shouldn't have the same CLSID. For example, I don't think that Microsoft uses unique CLSIDs to differentiate between the COM objects instantiated by its 64-bit and 32-bit Office products.
Anonymous

2023-07-14T00:16:23.03+00:00

@RLWA32 ， This is a suggested answer, both are fine.

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can 32bit and 64bit .net COM have same GUID

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