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Q145700: HOWTO: How the Server Use Is Determined by OLE

Article: Q145700
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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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

Additional query words: kbVBp400 kbVBp500 kbVBp600 kbVBp kbdsd kbDSupport kbOLE

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Keywords          : kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400 kbZNotKeyword3 kbVB16bitSearch
Issue type        : kbhowto

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