CoGetStandardMarshal function (combaseapi.h)

Creates a default, or standard, marshaling object in either the client process or the server process, depending on the caller, and returns a pointer to that object's IMarshal implementation.

Syntax

HRESULT CoGetStandardMarshal(
  [in]           REFIID    riid,
  [in]           LPUNKNOWN pUnk,
  [in]           DWORD     dwDestContext,
  [in, optional] LPVOID    pvDestContext,
  [in]           DWORD     mshlflags,
  [out]          LPMARSHAL *ppMarshal
);

Parameters

[in] riid

A reference to the identifier of the interface whose pointer is to be marshaled. This interface must be derived from the IUnknown interface.

[in] pUnk

A pointer to the interface to be marshaled.

[in] dwDestContext

The destination context where the specified interface is to be unmarshaled. Values come from the enumeration MSHCTX. Unmarshaling can occur either in another apartment of the current process (MSHCTX_INPROC) or in another process on the same computer as the current process (MSHCTX_LOCAL).

[in, optional] pvDestContext

This parameter is reserved and must be NULL.

[in] mshlflags

Indicates whether the data to be marshaled is to be transmitted back to the client process (the normal case) or written to a global table where it can be retrieved by multiple clients. Values come from the MSHLFLAGS enumeration.

[out] ppMarshal

The address of IMarshal* pointer variable that receives the interface pointer to the standard marshaler.

Return value

This function can return the standard return values E_FAIL, E_OUTOFMEMORY, and E_UNEXPECTED, as well as the following values.

Remarks

The CoGetStandardMarshal function creates a default, or standard, marshaling object in either the client process or the server process, as may be necessary, and returns that object's IMarshal pointer to the caller. If you implement IMarshal, you may want your implementation to call CoGetStandardMarshal as a way of delegating to COM's default implementation any destination contexts that you do not fully understand or want to handle. Otherwise, you can ignore this function, which COM calls as part of its internal marshaling procedures.

When the COM library in the client process receives a marshaled interface pointer, it looks for a CLSID to be used in creating a proxy for the purposes of unmarshaling the packet. If the packet does not contain a CLSID for the proxy, COM calls CoGetStandardMarshal, passing a NULLpUnk value. This function creates a standard proxy in the client process and returns a pointer to that proxy's implementation of IMarshal. COM uses this pointer to call CoUnmarshalInterface to retrieve the pointer to the requested interface.

If your OLE server application's implementation of IMarshal calls CoGetStandardMarshal, you should pass both the IID of (riid), and a pointer to (pUnk), the interface being requested.

This function performs the following tasks:

1. Determines whether pUnk is NULL.
2. If pUnk is NULL, creates a standard interface proxy in the client process for the specified riid and returns the proxy's IMarshal pointer.
3. If pUnk is not NULL, checks to see if a marshaler for the object already exists, creates a new one if necessary, and returns the marshaler's IMarshal pointer.

Requirements

See also

IMarshal