Mixing 64 and 32 bit applications pools on OWA website

May 23, 2009

If you need to create and run a 32-bit application pool on the same website you are running Exchange OWA, usually the Default Web Site, you need to make a couple changes. For example, you want to run an old ASP component that only runs in 32 bit mode.

1. Register the DLL - copy it to \Windows\SysWOW64 and run regsvr32 your.dll
2. Create a 32 bit application pool in IIS 7 - On the advanced settings, set Enable 32-bit applications = True
3. Create a subfolder and assign your 32-bit app pool to it.
4. Modify \Windows\system32\inetsrv\config\applicationhost.config:

   <location path="Default Web Site">
           <system.webServer>
               isapiFilters>
                   <clear />
                   <filter name="Exchange OWA Cookie Authentication ISAPI Filter" path="D:\Program Files\Microsoft\Exchange Server\ClientAccess\owa\auth\owaauth.dll" enabled="true" preCondition="bitness64" />
                   <filter name="Exchange ActiveSync ISAPI Filter" path="D:\Program Files\Microsoft\Exchange Server\ClientAccess\sync\bin\AirFilter.dll" enabled="true" preCondition="bitness64" />
               </isapiFilters>

   Notice the added preCondition=”bitness64″. This tells those filters to only run on 64 bit app pools.

Filed under: Microsoft, Windows |