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Q259205: APPC TP_STARTED Does Not Verify Local LU Alias By Default

Article: Q259205
Product(s): Microsoft SNA Server
Version(s): 
Operating System(s): 
Keyword(s): 
Last Modified: 18-APR-2000

This article discusses a Beta release of a Microsoft product. The information in this article is provided as-is and is subject to change without notice.

No formal product support is available from Microsoft for this Beta product. For information about how to obtain support for a Beta release, see the documentation that is included with the Beta product files, or check the Web location from which you downloaded the release.
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The information in this article applies to:

- Microsoft Host Integration Server 2000 
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SUMMARY
=======

When you use Host Integration Server 2000, an APPC application receives an AP_OK
return code when it calls TP_STARTED with an invalid local APPC LU alias.
However, the subsequent [MC_]ALLOCATE call fails with the following error
message:

  primary_rc = 0xF004 (AP_COMM_SUBSYSTEM_NOT_LOADED) secondary_rc = x020000F0

Unlike previous versions of SNA Server, Host Integration Server 2000 defers the
client-server resource location until the APPC application issues the
[MC_]ALLOCATE request when a local LU is provided to TP_STARTED. This change has
been implemented in Host Integration Server 2000 to improve client-server
resource location and load-balancing support. However, you can still configure a
registry parameter to revert to the previous behavior in earlier versions of SNA
Server.

For additional information about the AP_COMM_SUBSYSTEM_NOT_LOADED secondary
return codes, click the article number below to view the article in the
Microsoft Knowledge Base:

  Q148359 SNA Server APPC Error: F004 AP_COMM_SUBSYSTEM_NOT_LOADED

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

By default, when an APPC application provides a local LU alias to the TP_STARTED
call, Host Integration Server 2000 no longer verifies that the local LU has been
configured. Instead, the APPC application now contacts the Host Integration
Server when the [MC_]ALLOCATE request is issued to improve resource location and
load-balancing support.

This change has a side effect for APPC applications that require two-phase commit
support (if an APPC application issues TP_STARTED with syncpoint_rqd = AP_YES,
and [MC_]ALLOCATE with sync_level = AP_SYNCPT). By default, such applications
are not able to retrieve a valid Logical Unit of Work ID (luw_id) until after
the [MC_]ALLOCATE request is issued. In other words, such applications should
not call TP_STARTED followed by GET_TP_PROPERTIES to retrieve the luw_id until
after the [MC_]ALLOCATE request is issued.

However, to disable this behavior and enforce local LU alias verification for
TP_STARTED, or to receive a valid luw_id immediately after calling TP_STARTED,
the following registry parameter can be configured:

On the computer running Host Integration Server or on the Admin client:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaBase\Parameters\Client\
  GenerateLUWIDonTPSTARTED: REG_SZ: YES

-OR-

On the Host Integration Server end-user client:

  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SnaBase\Parameters\Client\
  GenerateLUWIDonTPSTARTED: REG_SZ: YES

NOTE: Unlike SNA Server, Host Integration Server 2000 does not support the
LUWIDSUP registry entry. Instead, this registry entry has been replaced with
GenerateLUWIDonTPSTARTED.

Also, the GetAPPCReturnCode function has been updated to return the following
error message when F004/020000F0 occurs:

  Local LU not configured on an active Node. Either the Local LU has not been
  configured, or its Node is not started.

Therefore, any APPC application that uses the GetAPPCReturnCode function to
convert the APPC error to a text string receives the correct error message.


Additional query words:

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Keywords          :  
Technology        : kbAudDeveloper kbHostIntegServ2000
Version           : :

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