Configuring a COM server to be run as a single instance in Server 2008.

Tip - RunAs(COM)-Configures a class to run under a specific user account when activated by a remote client without being written as a service application.

Details - When COM clients in the client sessions query interfaces of COM servers that are running in session 0, multiple instance of  the COM servers gets instantiate in client sessions even though COM server is running.  This can be avoided by changing the value of following registry key as “nt authority\system”.

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AppID

   {AppID_GUID}

      RunAs = nt authority\system

Note: We cannot use "nt authority\system" with a COM server that is not already started. 

Reference : http://msdn.microsoft.com/en-us/library/ms680046(v=VS.85).aspx

Posted By : Merlin S. Thadathil