Choosing a Threading Model

[This is preliminary documentation and subject to change.]

There are two versions of the XML control: a version with a rental model and a version with a free-threaded model. The rental model version is designed for single-threaded access. The free-threaded version is designed for multiple thread access.

The two versions are distinguished by their progIDs. To use the rental model control, use the "Microsoft.XMLDOM" progID. To use the free-threaded control, use the "Microsoft.FreeThreadedXMLDOM" progID.

If you plan for several threads to access your XML data from a single control, be sure to use the free-threaded control. If only one thread will access the XML data, use the rental model control since it will perform better.

The following is a sample global.asa file that creates session-level and application-level free-threaded versions of the XML control.

<SCRIPT LANGUAGE=VBScript RUNAT=Server>
  Sub Session_OnStart
    ON error RESUME next
     
    SET Application("AppFXMLdoc") = _
      server.CreateObject("Microsoft.FreeThreadedXMLDOM")
    SET Session("SessFXMLdoc") = _
      server.CreateObject("Microsoft.FreeThreadedXMLDOM")
  End Sub
  Sub Session_OnEnd
    ON error RESUME next
      
    SET Session("SessFXMLdoc") = nothing
    SET Application("AppFXMLdoc") = nothing
    Session("SessFXMLdoc") = empty
    Application("AppFXMLdoc") = empty
  End Sub
</SCRIPT>

Scripts accessing the Session and Application objects will be able to simultaneously access the "AppFXMLdoc" and "SessFXMLdoc" objects.