Interoperability of a first framework or platform (e.g., COM) and a second different framework or platform (e.g., .NET) is provided via an attribute mechanism. The attribute mechanism is provided in a non-COM based platform (e.g., .NET) to expose classes to COM. In this manner, a compiler (e.g., the .NET compiler) creates class and events interfaces and adds attributes to the class and interfaces as appropriate for correct interoperability and marshaling. By adding this attribute mechanism to a class in .NET, the .NET compiler is able to use the class declarations (such as public methods, properties, and events) to automatically generate a class interface and an events interface, including appropriate dispatch IDs and GUIDs. Validation is performed on the class being mapped to provide an indication, such as an error message or warning, to the user that the underlying framework marshaling layer cannot marshal certain data types as desired or expected.