internet information services process model chris adams iis technical lead wa microsoft corporation

1. Internet Information Services Process Model

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3. 3 IIS 4.0 Process Model: Modes Microsoft� IIS 4.0 (Windows NT� Option Pack) Two modes In-process (Inetinfo.exe) Out-of-process (Mtx.exe)

4. 4 IIS 4.0 Process Model: In-Process Benefits Performance is fast Less variables to break Drawbacks InetInfo service is vulnerable to unexpected shutdown

5. 5 In-Process Model

6. 6 IIS 4.0 Process Model: Isolation Integration with MTS Benefits Permits granular isolation from the site to the virtual directory level Runs as isolated individual process called MTX Drawbacks Performance Process delays between InetInfo and MTX WAM Maps requests to low or high isolation

7. 7 Out-of-Process Costs

8. 8 Out-of-Process Entire Costs

9. 9 Process Model IIS 5.0 Three modes: Low (IIS process) Medium (pooled) High (isolated) Low: Process runs totally under identity of system account Excellent for troubleshooting IIS to COM errors Isolated processes: uses COM Out of sync problems

10. 10 COM+ Integration Internals ASP thread pool (uses COM+ STA thread pool) ASP transactions (IIS utilities COM+ application) Out-of-process (medium or high): Process isolation for ISAPI By default, during installation, IIS creates three packages By default, processes created by IIS are run under the identity of IWAM_MachineName User identity is configurable

11. 11 Component Services Default Screen Shot

12. 12 Out-of-Process Application Properties Default Screen Shot

13. 13 Identity Configuration Screen Shot

14. 14 Metabase Stored Data Screen Shot

15. 15 ASP.NET and IIS 5.0 IIS in-process ISAPI applications Handled directly by InetInfo How does this differ from default handling? Inetinfo routes directly to ASPNET_WP.exe Is ASP.NET an in-process or out-of-proc ISAPI? An In-Proc ISAPI Application Is classic ASP an in-process ISAPI? ASP ISAPI can run either InProc or OOP If it is an in-process account, what account is the ISAPI running under? ASPNET � User created during ASP.NET Framework Install Why is this important? To understand what is loaded and running in the InetInfo process Default in-process ISAPIs

16. 16 ASP.NET and IIS 5.0 (2)

17. 17 Process Considerations In-process is sufficient to use: When hardware limitations restrict the system from having good performance running out-of-process On IIS 4.0, only when application code or third-party code has been thoroughly tested! On IIS 5.0 With enough power, most applications should stay in the medium-pooled process Keep in mind that making one call to one DLLHost is better than one DLLHost calling another, and another� When errors are occurring on the server It is frequently a good idea to isolate the problem to IIS or COM by moving the site/virtual directory in- or out-of-process If breaking while InProc, take out-of-process If breaking while out-of-process, move InProc

18. 18 Process Considerations (2) Out-of-process should be used: To isolate known problematic code On IIS 5.0 Only isolate high volume using high isolated Leave most sites running in pooled memory space On IIS 4.0 Troubleshooting or high volume sites are typically the only reason to run in high isolation

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