3270 Emulators and LUA Applications Stop Responding When They Use the Single Sign-On Feature (321245)


The information in this article applies to:

  • Microsoft SNA Server 4.0
  • Microsoft SNA Server 4.0 SP1
  • Microsoft SNA Server 4.0 SP2
  • Microsoft SNA Server 4.0 SP3
  • Microsoft SNA Server 4.0 SP4
  • Microsoft Host Integration Server 2000
This article was previously published under Q321245

SYMPTOMS

3270 emulators may stop responding (hang) shortly after they connect to a host session when they are configured to use the Single Sign-On (SSO) feature that is included with SNA Server or Host Integration Server 2000. Logical Unit Application (LUA) applications that are configured to use SSO may also experience this behavior.

From an end-user perspective, a typical scenario is that the 3270 emulator stops responding after you enter some data and then press ENTER to send the data to the host application. At this point, a 3270 emulator generally displays an X-CLOCK or an equivalent indicator in the Operator Information Area (OIA) at the bottom of the emulator window.

CAUSE

The SNA Server service (Snaservr.exe) does not respond to an incoming Function Management Interface (FMI) message from a 3270 emulator if all of the following conditions are true:
  • The 3270 emulator is using the LUA variant of the FMI or Emulator Interface Specification (EIS).
  • The host connection in SNA Manager is assigned to a host security domain, enabling it for use with SSO.
  • The data that is being sent to the host application by the 3270 emulator spans multiple Request Unit (RU) chains.
In this scenario, the SNA Server service does not send an ACKLUA (FMI Status Acknowledgment - LUA) message to the 3270 emulator (or LUA application). The 3270 emulator cannot send any additional data until the ACKLUA is received. At this point, the SNA Server service waits for the rest of the data so that it can scan the data as part of the SSO process. The result is that the 3270 emulator stops responding.

RESOLUTION

SNA Server 4.0

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Microsoft SNA Server version 4.0 service pack that contains this hotfix.

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, visit the following Microsoft Web site:

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

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical 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 hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
DateTimeVersionSizeFile name
23-May-200210:334.0.0.606468,864Snaservr.exe

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

Host Integration Server 2000

To resolve this problem, obtain the latest service pack for Host Integration Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

328152 How to Obtain the Latest Host Integration Server 2000 Service Pack

STATUS

SNA Server 4.0

Microsoft has confirmed that this is a problem in Microsoft SNA Server version 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4.

Host Integration Server 2000

Microsoft has confirmed that this is a problem in Microsoft Host Integration Server 2000. This problem was first corrected in Host Integration Server 2000 Service Pack 1.

MORE INFORMATION

As noted in the "Cause" section of this article, this problem affects only 3270 emulators that use the LUA variant of the FMI or EIS. Some third-party 3270 emulation products do use the LUA variant and may be affected by this problem. To determine whether a 3270 emulator uses the LUA variant of the FMI or EIS interface, turn on (enable) SNA Server 3270 message tracing, and then open a 3270 session. If byte 34 of Element #1 in the Open(SSCP) Request is set to 0x01, the LUA variant is being used. If byte 34 is set to 0x00, the LUA variant is not being used.

See the 3270 Emulator Interface Specification in the SNA Server or Host Integration Server 2000 SDK for more details about FMI or EIS and the LUA variant of the interface.

Modification Type:MinorLast Reviewed:10/6/2005
Keywords:kbBug kbfix kbHostIntegServ2000preSP1fix kbHostIntegServ2000SP1fix KB321245
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