Evaluating Application Changes Required for IIS 6.0 Worker Process Isolation Mode

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Applies To: Windows Server 2003, Windows Server 2003 with SP1

In most cases, the existing Web sites and applications can be hosted in worker process isolation mode without modification. However, the following are known application issues that can create incompatibilities with worker process isolation mode and require you to run IIS 6.0 in IIS 5.0 isolation mode.

  • Requires Inetinfo.exe. When the application must run in the same process with Inetinfo.exe, IIS must be configured to run in IIS 5.0 isolation mode because Inetinfo.exe does not process Web requests in worker process isolation mode. In worker process isolation mode, W3wp.exe processes Web requests.

  • Requires Dllhost.exe. When the application depends on Dllhost.exe to process Web requests for the application, IIS must be configured to run in IIS 5.0 isolation mode because Dllhost.exe is not available in worker process isolation mode.

  • Requires read raw data filters. If the application uses an ISAPI raw data filter, IIS must be configured to run in IIS 5.0 isolation mode.

  • Requires version 1.0 of the .NET Framework. When the application requires version 1.0 of the .NET Framework, IIS must be configured to run in IIS 5.0 isolation mode because version 1.0 of the .NET Framework is only supported in IIS 5.0 isolation mode.

  • Requires ISAPI filters or extensions that are incompatible with worker process isolation mode. When the application requires ISAPI filters or extensions that are incompatible with worker process isolation mode, IIS must be configured to run in IIS 5.0 isolation mode. ISAPI filters or extensions might be incompatible if the filter or extension has one of the following characteristics:

    • Runs in multiple instances and expects to be recycled by using the recycling provided in IIS 5.0.

    • Expects to have exclusive lock on a resource, such as a log file.

If any of the Web sites and applications running on the existing Web server has one or more of these characteristics, then do one of the following:

  • Configure IIS 6.0 to run in IIS 5.0 isolation mode to ensure Web site and application compatibility. If the Web sites and applications need to be hosted in IIS 5.0 isolation mode, then the migration process is complete.

  • Modify the existing applications to remove the dependencies.