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Q182915: 3270 Emulator Hangs and Returns X’1003’ Error to Mainframe

Article: Q182915
Product(s): Microsoft SNA Server
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbbuglist
Last Modified: 15-MAR-2000

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The information in this article applies to:

- Microsoft SNA Server, version 4.0 
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SYMPTOMS
========

A 3270 emulator may hang while receiving a screen of data from a mainframe. The
emulator screen may be partially filled with data when the emulator hangs. The
SNA Server computer that the emulator is connecting through logs a message
similar to the following in its Application Event log:

  Event ID: 21
  Source: SNA Server
  Description: (1124) Negative Response Sent on Connection <connection
  name> (SENSE = 1003).

SUBCODE INFORMATION:
X'1124' A negative response was sent and logged. This error normally follows a
more specific error message, depending on the type of negative response sent and
its cause. The SNA sense data provides details about the type of error.

This problem does not occur if the emulator connects to a mainframe through SNA
Server 3.0 SP2 and earlier.

In addition, this problem may not occur with all 3270 emulators. This problem has
been reproduced using NetSoft's NS/Elite 3270 emulator. It could not be
reproduced using the 3270 Applet included with SNA Server.


CAUSE
=====

SNA Server 4.0 incorrectly sets the ECI (End Chain Indicator) and CDI (Change
Direction Indicator) flags on the first segment of an RU (Request/Response Unit)
sent to a 3270 emulator that has indicated that it can receive RU segments.

When delivering RU segments, EC (End Chain) and CD (Change Direction) indicators
are supposed to be delayed if they occur in the RH (Request/Response Header) of
the RU's first segment until the last segment of the RU is sent to the
emulator.


STATUS
======

Microsoft has confirmed this to be a problem in SNA Server 4.0. This problem was
corrected in the latest SNA Server version 4.0 U.S.Service Pack. For information
on obtaining this Service Pack, query on the following word in the Microsoft
Knowledge Base (without the spaces):

  S E R V P A C K



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

When you start a 3270 session, the 3270 emulator indicates whether it supports
the delivery of RU segments. If the emulator supports the delivery of RU
segments, SNA Server can send data it receives from a mainframe to the emulator
as it is received. If the emulator indicates that it does not support the
delivery of RU segments, SNA Server will not send the data it receives to the
emulator until it receives the entire RU from the mainframe. The SNA Server
service then assembles the data into a complete RU before sending it to the
emulator. Please refer to the "Segment Delivery" section of the SNA Server 3270
Emulator Interface Specification manual for more details on this feature. This
manual is included with the Online SDK Documentation shipped with SNA Server.

IBM sense codes are defined in the IBM SNA Formats Guide (GA27- 3136). Sense code
X'1003' is defined as follows:

  Function Not Supported: The function requested is not supported. The function
  may have been specified by a formatted request code, a field in an RU, or a
  control character.

NetSoft NS/Elite is manufactured by NetSoft, Inc., a vendor independent of
Microsoft; we make no warranty, implied or otherwise, regarding this product's
performance or reliability.

Additional query words:

======================================================================
Keywords          :  kbbuglist
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400
Version           : WINDOWS:4.0
Issue type        : kbbug
Solution Type     : kbfix

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

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