# IFillLockBytes - Implementation

The system provides an IFillLockBytes implementation as part of its existing implementation of Compound Files. Downloading code can instantiate an asynchronous Compound File object by calling StgOpenAsyncDocFileOnIFillLockBytes and can instantiate an asynchronous byte array wrapper object on an existing file or byte array by calling either the StgGetIFillLockBytesOnFile function or the StgGetIFillLockBytesOnILockBytes function.

When to Use

Currently, URL monikers are the only users of OLE’s asynchronous storage implementation.

Remarks

FillAppend
  Writes a new block of bytes to the end of a byte array.
FillAt
  The system implementation does not support this method. Returns E_NOTIMPL.
SetFillSize
  Sets size of byte array. Returns E_FAIL from calls to ILockBytes::ReadAt that attempts to access data beyond the upper bound specified
Terminate
  Informs byte array that a download has been terminated, either successfully or unsuccessfully.