PRB: Server Stops Responding When You Call Microsoft Transaction Server Component Under Active Server Pages (260075)


The information in this article applies to:

  • Microsoft Internet Information Server 4.0
  • Microsoft Visual Basic Professional Edition for Windows 6.0
  • Microsoft Visual Basic Enterprise Edition for Windows 6.0
This article was previously published under Q260075

SYMPTOMS

When you call a Microsoft Transaction Server (MTS) component from a non-Microsoft Transaction Server component that is
  • running under Microsoft Active Server Pages (ASP) -and-

  • written in Microsoft Visual Basic
then your server may stop responding to ASP requests when it is placed under stress.

CAUSE

This behavior can happen if the calling component creates the second component through the use of CreateObject, instead of through the object context's CreateInstance method.

A call to Server.CreateObject always creates an MTS thread with a context wrapper. Therefore, the first object is created on an MTS thread and ends up creating a second object, which is an MTS object. CreateInstance should be used when you create an MTS object from an object in Microsoft Transaction Server.

Another way to avoid this problem is to configure the calling component into an MTS server package so that it will start in a different process than if it were created in Inetinfo.exe's process space.

RESOLUTION

Because the calling component is running under ASP, it has access to all of the ASP properties and methods. Instead of creating the component using CreateObject, you can use the CreateInstance property of the ObjectContext object. For an example of how to accomplish this, see the example in the "More Information" section.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

  1. Create a new ActiveX DLL project in Visual Basic.
  2. Rename the project from "Project1" to NotAnMTSComponent.
  3. Rename "Class1" to CNotAnMTSComponent.
  4. Paste the following code into cNotAnMTSComponent:
    Option Explicit

Public Sub Test()

    Dim x As Object
    
    Set x = CreateObject("MyMTSComponent.cMTSComponent")
    x.DoSomething
    Set x = Nothing
    
    
End Sub
  5. From the Visual Basic File menu, select Add Project, and create a new ActiveX DLL.
  6. Rename the project from "Project1" to MyMTSComponent.
  7. Rename "Class1" to cMTSComponent.
  8. Set the MTSTransactionMode of cMTSComponent to 2 - Requires Transaction.
  9. From the Project menu, select References, and add a reference to Microsoft Transaction Server Type Library.
  10. Paste the following code into cMTSComponent:
    Option Explicit

Public Sub DoSomething()

    Dim oc As ObjectContext
    Dim x  As Integer
    Dim strNothing As String
    
    
    Set oc = GetObjectContext
    
    'Waste some time here
    For x = 1 To 1000
        strNothing = strNothing + String(1000 * Rnd() + 1, " ")
    Next x
        
    
    oc.SetComplete
    Set oc = Nothing
    

End Sub
  11. Compile both .dll files.
  12. Use your MTS Explorer to create a new package, and then add MyMTSComponent.dll to the package.
  13. Create an ASP page named Test.asp. Paste the following code into it:
    <%@ LANGUAGE = VBScript %>
<html>
<body>
<%
     dim myObj
     set myObj = SErver.CreateObject("NotAnMTSComponent.cNotAnMTSComponent")

%>

Done!
</body>
</html>
  14. Use the Internet Services Manager to create a new application. Make its path C:\Inetpub\Wwwroot\Test. (Modify the path as necessary to suit your Internet Information Services [IIS] setup.) Ensure that the application is running in a separate process. Name the application Test.
  15. Put Test.asp into C:\Inetpub\Wwwroot\Test.
  16. Use a Web application stress tool (for example, http://webtool.rte.microsoft.com/) to apply a load to your Web site. Your application should stop responding ("hang").
To solve the problem, change the code in cNotAnMTSComponent to:
Option Explicit

Public Sub Test()

    Dim x As Object
    Dim oc as ObjectContext

    Set oc = GetObjectContext
    Set x = oc.CreateInstance("MyMTSComponent.cMTSComponent")
    x.DoSomething
    Set x = Nothing
    set oc = nothing
    
End Sub

REFERENCES

Ted Pattison provides good information on this topic in his book Programming Distributed Applications with COM and Microsoft(r) Visual Basic(r) 6.0 (pages 284-288) and in "Creating Objects Properly in an MTS App" in the August 1999 edition of the Microsoft Independent Developer.
Modification Type:MajorLast Reviewed:11/18/2003
Keywords:kbprb kbScalability KB260075
©2003 Microsoft Corporation. All rights reserved.