JR27955: CSWIN: LUA HANG IF NOTIFY SENT BEFORE ACTLU RSP

Communications Server for Windows, Version 6.1.2 -- Latest Fix Pack

APAR status

• Closed as program error.

Error description

• Communications Server for Windows, Version 6.1.2
  ------------------------------------------------
  LUA application hangs when the link is stopped (or fails) and is
  restarted, because the RUI_INIT verb does not return.
  

Local fix

• Stop the application before restarting the link.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of LUA applications.               *
  ****************************************************************
  * PROBLEM DESCRIPTION: Trace shows:                            *
  *                      RUI_INIT -->                            *
  *                                 (link activation)            *
  *                                 <-- ACTLU RQ                 *
  *                                 NOTIFY RQ (SLU enable)->     *
  *                                 ACTLU +RSP                   *
  *                                 <-- NOTIFY -RSP 80050000     *
  *                      <-- RUI_INIT SESSION_FAILURE            *
  *                                   LU_COMPONENT_DISCONNECTED  *
  *                      RUI_INIT -->                            *
  *                      The new RUI_INIT never returns.         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The host correctly rejected the NOTIFY with sense code
  8005000 "No Session", since it had not received the ACTLU RSP
  first. It then processed the ACTLU +RSP and believes the
  SSCP-LU half-session is available for use. When CSWIN
  received the 80050000 sense code, it marked the LU as inactive
  internally. This caused the RUI_INIT failure. The subsequent
  RUI_INIT will hang pending activation of the LU, which is
  assumed to be possible because the link is active, or until
  the link terminates. However, this will not happen in this
  case, because the host thinks the LU is active, and CSWIN
  thinks it is inactive and cannot do anything to request
  activation.
  .
  The cause of this problem is that the NOTIFY RQ was
  transmitted before the ACTLU +RSP. Additional examination
  revealed a severe level of network-level retransmissions due
  to an external network issue. In CSWIN, the ACTLU RSP and the
  NOTIFY RQ are processed by two different queues, and the
  pressure caused by the retransmissions caused the queue
  processing the ACTLU RSP to be slightly delayed relative to
  the NOTIFY RQ.
  

Problem conclusion

• Code has been modified to ensure that the ACTLU RSP is
  transmitted before the NOTIFY RQ.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Modules/Macros

• APPN     LLC2
  

Fix information

• Fixed component name

  COMM SERV NT 6.

• Fixed component ID

  5639F2503

Applicable component levels

• R612 PSY

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