How To How the Server Use Is Determined by OLE (145700)


The information in this article applies to:

  • Microsoft Visual Basic Learning Edition for Windows 5.0
  • Microsoft Visual Basic Learning Edition for Windows 6.0
  • Microsoft Visual Basic Professional Edition for Windows 5.0
  • Microsoft Visual Basic Professional Edition for Windows 6.0
  • Microsoft Visual Basic Enterprise Edition for Windows 5.0
  • Microsoft Visual Basic Enterprise Edition for Windows 6.0
  • Microsoft Visual Basic Control Creation Edition for Windows 5.0
  • Microsoft Visual Basic Standard Edition, 32-bit, for Windows 4.0
  • Microsoft Visual Basic Professional Edition, 16-bit, for Windows 4.0
  • Microsoft Visual Basic Professional Edition, 32-bit, for Windows 4.0
  • Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows 4.0
  • Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows 4.0
This article was previously published under Q145700

SUMMARY

When an OLE Automation client requests an object that can be provided by more than one server, OLE uses a predefined set of rules to determine which server is used to supply that object. This article lists the order used by OLE when providing objects.

MORE INFORMATION

Each object that can be provided to an OLE Automation client can be identified by an unique 64-bit number called a CLSID. The system registry contains a key called CLSID (immediately off of HKEY_CLASSES_ROOT), which has as subkeys every CLSID registered on the system. The subkeys of each CLSID hold information for each object, including the path and filename of the server(s) that can be used to provide that object, according to this table: 
   Key               Server
   ---------------------------------------------------------------------
   InprocServer      16-bit DLL (in-process) server
   InprocServer32    32-bit DLL (in-process) server
   OutprocServer     16-bit EXE (out-of-process) server
   OutprocServer32   32-bit EXE (out-of-process) server
It is possible (and completely allowed by OLE) to have more than one of the above keys beneath a given CLSID. If this situation occurs, OLE uses a predefined order to determine which server is used to provide an object. This decision is based both on the bitness of the potential OLE Automation client and the bitness of the operating system. OLE uses this order:

  1. In-process (DLL) server of same bitness as the client
  2. 32-bit local server (only for 16-bit clients on a 32-bit OS)
  3. Out of process server of same bitness as client
  4. Out of process server of other bitness as client
Modification Type:MinorLast Reviewed:7/1/2004
Keywords:kbhowto KB145700
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