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Q311584: LUA App May Hang If VTAM Recycled While RUI_WRITE Outstanding

Article: Q311584
Product(s): Microsoft SNA Server
Version(s): 4.0
Operating System(s): 
Keyword(s): kbDSupport sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4
Last Modified: 08-MAY-2002

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

- Microsoft SNA Server, version 4.0 
- Microsoft Host Integration Server 2000 
-------------------------------------------------------------------------------

SYMPTOMS
========

A logical unit application (LUA) application may stop responding ("hang") if it
has an outstanding RUI_WRITE when Virtual Telecommunications Access Method
(VTAM) is recycled on the IBM mainframe.

This can occur when the RUI_WRITE was issued to send an INITSELF Request Unit
(RU) to the host system.

CAUSE
=====

If VTAM is unavailable when an LUA application issues an RUI_WRITE(INITSELF) to
an IBM mainframe, the INITSELF may not be responded to. Once VTAM is available,
it may issue an ACTLU(ERP) to recover the session over which the LUA application
was communicating. When this occurs, the Request Unit Interface (RUI) library
(Winrui32.dll) does not return an error on the outstanding RUI_WRITE() verb when
the host issues the ACTLU(ERP) to recover the session. The result is that the
outstanding RUI_WRITE() verb never finishes, which may cause the LUA application
to stop responding.

RESOLUTION
==========

SNA Server 4.0

No fix is available for this problem in SNA Server 4.0 at this time.

Host Integration Server 2000

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem. This fix may receive additional
testing at a later time, to further ensure product quality. Therefore, if you
are not severely affected by this problem, Microsoft recommends that you wait
for the next Microsoft Host Integration Server 2000 service pack that contains
this fix.

To resolve this problem immediately, contact Microsoft Product Support Services
to obtain the fix. For a complete list of Microsoft Product Support Services
phone numbers and information about support costs, please go to the following
address on the World Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English version of this fix should have the following file attributes or
later:

+-----------------------------------+
| File name    | Date       | Time  | 
+-----------------------------------+
| Winrui32.dll | 01/25/2001 | 14:42 | 
+-----------------------------------+

NOTE: Because of file dependencies, the most recent fix that contains the above
files may also contain additional files.



NOTE: If this product was already installed on your computer when you purchased
it from the Original Equipment Manufacturer (OEM) and you need this fix, please
call the Pay Per Incident number listed on the above Web site. If you contact
Microsoft to obtain this fix, and if it is determined that you only require the
fix you requested, no fee will be charged. However, if you request additional
technical support, and if your no-charge technical support period has expired,
or if you are not eligible for standard no-charge technical support, you may be
charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the
following article in the Microsoft Knowledge Base:

  Q154871 Determining If You Are Eligible for No-Charge Technical Support

STATUS
======

SNA Server 4.0

Microsoft has confirmed this to be a problem in Microsoft SNA Server version
4.0,.


Host Integration Server 2000

Microsoft has confirmed this to be a problem in Microsoft Host Integration Server
2000.

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

The following is an example of a scenario that can result in the problem
described in this article:

+-------------------------------------------------------------------+
| LUA Application        | SNA/HIS 2000 Server      | Host          | 
+-------------------------------------------------------------------+
| RUI_WRITE(INITSELF) -> |                          |               | 
+-------------------------------------------------------------------+
|                        | INITSELF ->              |               | 
+-------------------------------------------------------------------+
|                        |                          | <- ACTLU(ERP) | 
+-------------------------------------------------------------------+
|                        | ACTLU +RSP ->            |               | 
+-------------------------------------------------------------------+
|                        | NOTIFY(SLU Enabled) ->   |               | 
+-------------------------------------------------------------------+
|                        | <- FMIST(LU Reactivated) |               | 
+-------------------------------------------------------------------+

The IBM mainframe doesn't respond to the INITSELF because VTAM is not available.
Once VTAM is available, it sends an ACTLU(ERP) to recover the session. The SNA
Server service (Snaservr.exe) responds to the ACTLU(ERP) with the NOTIFY and it
sends a Function Management Interface (FMI) Session Status (LU Reactivated)
message to the RUI library. The RUI library fails to return an error on the
outstanding RUI_WRITE to indicate that the RUI_WRITE will not be responded to.

For additional information on SNA Server and Host Integration Server 2000 support
for ACTPU(ERP) and ACTLU(ERP) RUs, click the article number below to view the
article in the Microsoft Knowledge Base:

  Q138469 SNA Server Support for ACTPU (ERP) and ACTLU (ERP)

Additional query words:

======================================================================
Keywords          : kbDSupport sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4 
Technology        : kbAudDeveloper kbSNAServSearch kbHostIntegServ2000 kbSNAServ400
Version           : :4.0
Issue type        : kbbug
Solution Type     : kbnofix

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

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