CPIC applications no longer limited to single local APPC LU (233373)


The information in this article applies to:

  • Microsoft SNA Server 4.0
  • Microsoft Host Integration Server 2000
  • Microsoft Host Integration Server 2000 SP1
  • Microsoft Host Integration Server 2000 SP2
  • Microsoft Host Integration Server 2004
This article was previously published under Q233373

SYMPTOMS

The SNA Server CPIC interface (Wcpic32.dll) is designed to use a single Local APPC LU for all conversations initiated by a CPIC application. This behavior is described in the following Knowledge Base article:

181123 CPIC application limited to single local APPC LU

Note that this behavior prevents a CPIC application from making use of different pooled Local APPC LUs to reach one or more Remote APPC LUs residing on one or more remote systems. While this continues to be the default behavior for SNA Server 2.0, 2.1, 2.11, 3.0, and 4.0 (all service pack levels), an update to SNA Server 4.0 Service Pack 2 (SP2) is now available that implements a new registry parameter to allow a CPIC application to use multiple Local APPC LUs. See the "More Information" section for more details.

RESOLUTION

To resolve this problem, obtain the latest service pack for SNA Server version 4.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

215838 How to obtain the latest SNA Server version 4.0 service pack

STATUS

Microsoft has confirmed that this is a problem in Microsoft SNA Server version 4.0, 4.0 SP1, and 4.0 SP2. This problem was first corrected in SNA Server version 4.0 Service Pack 3.

MORE INFORMATION

After you apply the updated Wcpic32.dll and configure the GETNEWTPID registry entry (as defined below), a CPIC application can allocate conversations using different Local APPC LUs. However, note the following behavior:
  • The CPIC application needs to call CMINIT (Initialize_Conversation) prior to calling CMALLC (Allocate) to receive a new Local APPC LU. If the CPIC application only calls CMINIT once, followed by two or more CMALLC requests, only one Local APPC LU is used for all conversations.
  • Even when calling CMINIT more than once, a CPIC application may still receive the same Local APPC LU for multiple conversations. There is not any "balancing" of conversation use across different Local APPC LUs from a CPIC application.
  • A CPIC application still tends to get conversations through one SNA Server. A single CPIC application doesn't "balance" conversation requests across different SNA Servers.
This update is intended for SNA Servers or SNA Windows NT client computers running SNA 4.0 SP2. This update should be applied to any computers that support CPIC applications that require access through more than one Local APPC LU. After the update is applied, add the following registry key on the computer:

HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/SnaBase/ Parameters/Client/

GETNEWTPID: REG_SZ: YES

The presence of GETNEWTPID under this registry key enables this new behavior for CPIC applications.
Modification Type:MinorLast Reviewed:6/23/2006
Keywords:kbHotfixServer kbbug kbfix kbQFE kbsna400sp3fix KB233373
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