Primary Interop Assembly (PIA)

Question

Hi I want to know that What benefit do you get from using a Primary Interop Assembly (PIA)?

Vulpes · Answer

The benefit of using a PIA for a particular COM component is that you are using the 'official' version produced by the author of the component which aids interoperability. If you produce your own interop assembly using tlbimp.exe then it will be incompatible with an assembly produced by another developer because the types will not be regarded as being equivalent This is no longer a problem from .NET 4.0 onwards which now supports type equivalence for linked interop types. So if two assemblies each link to an interop type those types are regarded as equivalent provided that they represent the same underlying COM type no matter how they were generated. This of course means that PIAs are no longer needed.

Hemant Kumar · Answer

An interop assembly is a collection of types that are deployed versioned and configured as a single unit. However unlike other managed assemblies an interop assembly contains type definitions (not implementation) of types that have already been defined in COM. http://msdn.microsoft.com/en-us/library/aa302338.aspx