IMarshal::ReleaseMarshalData method (objidl.h)

Article
08/19/2022

Destroys a marshaled data packet.

Syntax

HRESULT ReleaseMarshalData(
  [in] IStream *pStm
);

Parameters

[in] pStm

A pointer to a stream that contains the data packet to be destroyed.

Return value

This method can return the standard return values S_OK and E_FAIL, as well as any of the stream-access errors for the IStream interface.

Remarks

If an object's marshaled data packet does not get unmarshaled in the client process space and the packet is no longer needed, the client calls ReleaseMarshalData on the proxy's IMarshal implementation to instruct the object to destroy the data packet. The call occurs within the CoReleaseMarshalData function. The data packet serves as an additional reference on the object, and releasing the data is like releasing an interface pointer by calling Release.

If the marshaled data packet somehow does not arrive in the client process or if ReleaseMarshalData is not successfully re-created in the proxy, COM can call this method on the object itself.

Notes to Callers

You will rarely if ever have occasion to call this method yourself. A possible exception would be if you were to implement IMarshal on a class factory for a class object on which you are also implementing IMarshal. In this case, if you were marshaling the object to a table where it could be retrieved by multiple clients, you might, as part of your unmarshaling routine, call ReleaseMarshalData to release the data packet for each proxy.

Notes to Implementers

If your implementation stores state information about marshaled data packets, you can use this method to release the state information associated with the data packet represented by pStm. Your implementation should also position the seek pointer in the stream past the last byte of data.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps \| UWP apps]
Minimum supported server	Windows 2000 Server [desktop apps \| UWP apps]
Target Platform	Windows
Header	objidl.h (include ObjIdl.h)

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