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Q247319: PRB: PUBLIC Variables Not Released from InProcess Servers in ASP

Article: Q247319
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbAutomation kbInternet kbvfp600 kbGrpDSFox kbDSupport
Last Modified: 11-DEC-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Public variables declared in an in-process Microsoft Visual FoxPro OLE
Automation Server, launched from an ASP page, are not released when the OLE
Automation Server is released.

CAUSE
=====

PUBLIC variables declared within an in-process OLE Automation Server are public
to the thread and any object on the thread. PUBLIC variables are not released
until the thread has been uninitialized and the client has unloaded the
in-process server. Setting the instance of the in-process server object to
"nothing" does not unload the server.

RESOLUTION
==========

Set the scope of variables used within in-process OLE Automation Servers, used
with Active Server Pages, to PRIVATE rather than PUBLIC.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new project named MTHREAD.

2. Add a new program file to the project, using the following code:

  DEFINE CLASS mthread AS CUSTOM OLEPUBLIC

     FUNCTION PublicHit
        LPARAMETER lnSecs
        LOCAL x
        lnSecs=IIF(EMPTY(lnSecs),0,lnSecs)

        IF lnSecs > 60
           lnSecs = 61
        ENDIF

        IF VARTYPE(gnPubValue) = "N"
           gnPubValue = gnPubValue + 1
        ELSE
           PUBLIC gnPubValue
           gnPubValue = 1
        ENDIF

        IF VARTYPE(gnPrivValue) = "N"
           gnPrivValue = gnPrivValue + 1
        ELSE
           PRIVATE gnPrivValue
           gnPrivValue = 1
        ENDIF

        DECLARE Sleep IN WIN32API INTEGER
        FOR x=1 TO lnSecs
           FOR x=1 TO lnSecs
              Sleep(1000)
           ENDFOR
        ENDFOR

        DECLARE INTEGER GetCurrentThreadId IN WIN32API
        lcHTML = [<p><table style="background:black;color:white">] + CHR(13) + ;
           [<tr><td style="font:normal normal 14pt Verdana">] + ;
           "The request completed in " + TRANS(lnSecs) + " seconds." + [</td></tr>] +CHR(13) +;
           [<table>] + CHR(13) + ;
           "The current Thread ID is: " + TRANS(GetCurrentThreadId()) + "<p>"+CHR(13) + ;
           "The Public Value  (gnPubValue) : = " + TRANS(gnPubValue) + "<br>"+ CHR(13) + ;
           "The Private Value (gnPrivValue): = " + TRANS(gnPrivValue) + "<br>"

        RETURN lcHTML
     ENDFUNC
  ENDDEFINE

3. Click the Build button on the Project Manager, and select either a
  Single-threaded COM server (dll) or a Multi-threaded COM server (dll).

4. Install the COM Server and run-time files on a computer running Internet
  Information Server.

5. Register the COM Server.

6. Create an Active Server Page named TEST.ASP in the IIS WWWROOT directory
  using the following code, and make certain that the directory has execute
  privileges:

  <%@ Language=VBScript %>
  <HTML>
  <HEAD>
  <META NAME="GENERATOR" Content="Microsoft Visual Studio 6.0">
  </HEAD>
  <BODY>

  <%
  Set oVFPApp = Server.CreateObject("mthread.mthread")

  Response.Write oVFPApp.PublicHit

  set oVFPApp = nothing

  %>	

  </BODY>
  </HTML>

7. Launch your Web Browser and navigate to the Active Server Page that was
  created in step 4. Refresh the page several times, and note that the value of
  gnPubValue is incremented each time the page is refreshed.

8. Close your Web Browser.

9. Launch your Web Browser and navigate to the Active Server Page that was
  created in step 4. Note that the value of gnPubValue is not 1.

REFERENCES
==========

  Q156547 HOWTO: Manually Register a Custom OLE Server

  Q156014 HOWTO: Set Up OLE Automation in Visual FoxPro

Additional query words:

======================================================================
Keywords          : kbAutomation kbInternet kbvfp600 kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbprb

=============================================================================

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