FIX: Large Number of Methods in an OLE Interface Causes Failure

ID: Q170989

The information in this article applies to:

• Microsoft OLE Libraries included with: - Microsoft Win32 Software Development Kit (SDK)

SYMPTOMS

Under Windows NT 4.0, no more than 110 methods can be present in an OLE automation dual interface that is remoted via type library marshalling. Some applications, such as Microsoft Word, have automation interfaces containing more than 110 methods. This can cause crashes and other unexpected behavior when a controller invokes an automation method in such a server.

The limit under Windows 95 is 512 methods per dual interface.

CAUSE

This problem is caused by a marshalling bug in the RPC runtime libraries.

RESOLUTION

The limit on the number of methods in an interface has been increased in the later releases of the RPC libraries.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. The limit on the number of interface methods has been increased in Windows NT 4.0 Service Pack 2 (see the MORE INFORMATION section of this article).

MORE INFORMATION

Currently the maximum number of methods in an OLE automation dual interface are:

Windows NT 4.0       -   110 methods
Windows NT 4.0 SP2   -   512 methods
Windows NT 4.0 SP3   -  1024 methods
Windows 95           -   512 methods

Keywords          : LeTwoAto 
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix

Last Reviewed: October 30, 1997