Improved APPC/CPIC Performance on SNA Client Computer

ID: Q193815

The information in this article applies to:

Microsoft SNA Server, versions 4.0, 4.0 SP1

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SUMMARY

When an APPC application calls TP_ENDED (to end the last conversation) from an SNA Server Windows NT or Windows 95 or Windows 98 client computer, the underlying LAN session to the SNA Server is dropped. If the application immediately calls TP_STARTED and [MC_]ALLOCATE to invoke a new conversation, a new LAN session is established to the SNA Server, and the user is authenticated again by the server. This can significantly reduce APPC application performance if the program continuously starts, ends, and restarts new conversation requests.

MORE INFORMATION

An update to Snadmod.dll for SNA Server 4.0 is available which improves performance. Instead of closing a client-server connection immediately after the last conversation ends, Snadmod.dll now waits a short period before it closes the LAN connection. The idea is that if the application starts a new conversation within this period, the snadmod.dll can avoid expensive logon validations and resource allocations by reusing the existing connection. The delay is configurable through the following registry parameter.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

SNA Server Windows NT Client

Apply the hotfix.

Start the Windows NT Registry Editor (Regedt32.exe) and find the following key:


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaBase
       \Parameters\

Add the following entry to this key:
```
       Value Name: CloseTimeout
       Data Type: REG_DWORD
       Data (Decimal): <value> 
```
Where value is the number of seconds. If this entry is not specified, the CloseTimeout value internally defaults to 10 seconds.

SNA Server Windows 95 or Windows 98 Client

Apply the hotfix.

Start the Windows 95/98 Registry Editor (Regedit.exe) and find the following key:
```
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SnaBase
       \Parameters\  
```

Add the following new DWORD value:
```
       CloseTimeout
       Value Data (Decimal): <value> 
```
Where value is the number of seconds. If this entry is not specified, the CloseTimeout value internally defaults to 10 seconds.

This update applies to any SNA Server Windows NT, Windows 95, or Windows 98 client which runs an APPC or CPIC application to connect through an SNA Server running on a separate computer. The SNA Server does not need to be updated, and can remain at SNA Server 4.0 or a prior release. If the application is running on the server itself, it may still establish a LAN session to use resources provided by another SNA Server in the subdomain. In this case, this update should be applied to the server (that is, the computer where the application is running).

RESOLUTION

Microsoft has produced an update to SNA Server 4.0 which improves performance, as described in this article. This update is in included 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

Additional query words:

Keywords :
Version : WINDOWS:4.0,4.0 SP1
Platform : WINDOWS
Issue type : kbinfo