This function destroys a previously marshaled data packet.
This function supports the standard return values E_FAIL, E_INVALIDARG,
E_OUTOFMEMORY, and E_UNEXPECTED, as well as the following:
The data packet was successfully destroyed.
An IStream error dealing with the pStm parameter.
The CoInitialize function was not called on the current thread before this function was called.
The CoReleaseMarshalData function performs the following tasks:
The function reads a CLSID from the stream.
If COM's default marshaling implementation is being used, the function gets an IMarshal pointer to an instance of the standard unmarshaler.
If custom marshaling is being used, the function creates a proxy by calling the CoCreateInstance function, passing the CLSID it read from the stream, and requesting an IMarshal interface pointer to the newly created proxy.
Using whichever IMarshal interface pointer it has acquired, the function calls IMarshal::ReleaseMarshalData.
Typically your application will not call this function. It might need to call this function only if using custom marshaling to write and use a special implementation of IMarshal. The following are examples of situations for which CoReleaseMarshalData should be called:
A failed attempt has been made to unmarshal the data packet.
A marshaled data packet has been removed from a global table.
As an analogy, the data packet can be thought of as a reference to the original object, just as if it were another interface pointer being held on the object. Like a real interface pointer, that data packet must be released at some point. The use of IMarshal::ReleaseMarshalData to release data packets is analogous to the use of IUnknown::Release to release interface pointers.
Note that your application does not need to call CoReleaseMarshalData after a successful call of the CoUnmarshalInterface function. That function releases the marshal data as part of its processing.
To determine whether the platform supports this function, see Determining Supported COM APIs.