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Q140609: TPSTART Enhanced to Support 16-bit Windows Applications

Article: Q140609
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11 SP1;2.11 SP2,3.0 (all SP),4.0,4.0 SP1,4.0 SP2,4.0 SP3
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11 SP1, 2.11 SP2, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, on platform(s):
   - the operating system: Microsoft Windows NT 
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SYMPTOMS
========

When you attempt to invoke a 16-bit Windows application with TPSTART.EXE, the
invokable transaction program (TP) application program starter for SNA Server
Windows NT clients, the following errors occur:

- On Windows NT 3.5:

  16-bit Windows subsystem
  NTVDM encountered a system error. Access is denied

  Choose close to terminate the app, or ignore to continue

  After pressing Ignore, this popup occurs 10-12 times. After choosing Ignore
  each time, the application finally starts. However, subsequent attempts to
  autostart the application fail.

- On Windows NT 3.51:

  TPSTART.EXE calls CreateProcess properly, but it receives an Error 5
  (ACCESS_DENIED).

CAUSE
=====

TPSTART.EXE does not support the startup of 16-bit Windows applications.

The TPSTART.EXE program is setting the DETACHED_PROCESS flag when calling
CreateProcess, which causes the startup of 16-bit Windows applications to fail
with ACCESS_DENIED. This problem does not occur when starting 32-bit Windows
applications, even though the 32-bit application is not a detached process.

Also, if the TP is configured as queued (with SNAServiceType=5), SNA Server does
not detect that the application has ended since the default Windows NT virtual
DOS machine (VDM) is still running. This causes a second invocation of the TP to
fail.

RESOLUTION
==========

Microsoft has updated the file <snaroot>\SYSTEM\TPSTART.EXE to correct
this problem.

To support autostarting of 16-bit Windows applications, the following new
TP-specific registry settings are now supported under the subtree
HKEY_LOCAL_MACHINE under the subkey:

  /SYSTEM/CurrentControlSet/Services/SnaBase/Parameters/TPs/<tpname>/ 
  Parameters/ 

Add following information:

  "Value Name: Win16App
  Data Type: REG_SZ
  Data: YES" (without the quotation marks)

The following entry under the same subkey is also required to autostart 16- bit
Windows applications:

  "Value Name: SeparateWowVDM
  Data Type: REG_SZ
  Data: YES" (without the quotation marks)

This causes TPSTART.EXE to start the 16-bit application in its own Windows NT
VDM. This entry is required if TP is queued (where SNAServiceType=5). If the TP
is configured as queued, and SeparateWowVDM is not set to YES, then the TP is
only invoked once. Subsequent attempts to start the TP fail, because according
to SNA Server the TP is still running, because SNA Server finds that the Windows
NT VDM (NTVDM) process ID is still running. Starting a separate NTVDM corrects
this problem because the NTVDM process ends when the 16-bit Windows application
ends.

STATUS
======

This feature is included in the latest U.S. Service Pack for SNA Server for
Windows NT, version 2.11. For information on obtaining the Service Pack, query
on the following word in the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K

Additional query words: prodsna appc cpic

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Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch
Version           : WINDOWS:2.0,2.1,2.11 SP1;2.11 SP2,3.0 (all SP),4.0,4.0 SP1,4.0 SP2,4.0 SP3

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