Article: Q175375
Product(s): Microsoft SNA Server
Version(s): WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Operating System(s):
Keyword(s): kbsna300sp1 kbsna300sp2 kbsna300sp3 kbsna300sp4 sna4 kbsna400sp1 kbsna400sp2
Last Modified: 13-JUN-2001
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The information in this article applies to:
- Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2
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SUMMARY
=======
SNA Server versions 3.0 through 4.0 SP2 have a new Logical Unit of Work
Identifier (LUW_ID) instance format for LU 6.2-based conversations. Outlined
below are the changes that have been made:
+------------------------------------------------------+
| SNA Server 3.0 | Previous Versions |
+------------------------------------------------------+
| Byte 1- Year (high) | Byte 1- Hundredths of a second |
+------------------------------------------------------+
| Byte 2- Year (low) | Byte 2- Seconds |
+------------------------------------------------------+
| Byte 3- Month | Byte 3- Minute |
+------------------------------------------------------+
| Byte 4- Day | Byte 4- Hour |
+------------------------------------------------------+
| Byte 5- Hour | Byte 5- Day |
+------------------------------------------------------+
| Byte 6- Minute | Byte 6- Month |
+------------------------------------------------------+
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| SNA Server 4.0 Post-SP2 |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Byte 1- Year (high) |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Byte 2- Year (low) |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Byte 3-6- Flipped hexidecimal unsigned long integer containing the number of hundredths of a second in this year (but assuming each month is 31 days). The maximum value of (12/31 23.59.59.99) is 3214079999 or 0xBF92F7FF. If this value clashes with a previously generated value, the number is incremented by one. |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
NOTE: The algorithm is changed in SNA Server 4.0 post-SP2 to prevent possible
clashes in the logical unit of work generated by an SNA Server.
MORE INFORMATION
================
The LUW_ID is used to identify conversations that are part of a single Syncpoint
transaction. All conversations with the same LUW_ID are committed (or backed
out) at the same time. SNA Server 3.0 (not 2.11) assigns two LUW_IDs to a
transaction program (TP) when the TP is started. In the case of locally started
TPs, this is when the TP_STARTED verb is issued. The first LUW_ID is the TP's
protected LUW_ID and is used by SNA Server as the LUW_ID for all synclevel
Syncpoint conversations allocated by the TP. When the TP issues an (MC_)Allocate
verb with synclevel Syncpoint, SNA Server generates an Attach containing the
TP's current protected LUW_ID.
The second LUW_ID is the TP's unprotected LUW_ID. It is used on all conversations
allocated by the TP with a synclevel other than Syncpoint.
For remotely initiated TPs, the incoming Attach may contain an LUW_ID for the TP;
it is mandatory if the conversation is synclevel Syncpoint. For synclevel
Syncpoint conversations, SNA Server saves the LUW_ID as the TP's protected
LUW_ID and generates a new unprotected LUW_ID for it. For conversations other
than Syncpoint, SNA Server saves the LUW_ID as the TP's unprotected LUW_ID and
generates a new protected LUW_ID.
SNA Server generates LUW_IDs by concatenating:
- The fully qualified name of the local LU, preceded by a single byte
indicating its length.
- A 6-byte LUW instance number, generated from the current date and time (see
above summary).
- A 2-byte LUW sequence number, initialized to 1.
There are times when certain non-Syncpoint-related TPs (host or SNA Server based)
make use of the unprotected LUW_ID for accounting purposes and extract this
field using the GET_TP_PROPERTIES verb. These applications may become confused
if they are not aware of the changes that have been made to the LUW_ID instance
field.
NOTE: COM Transaction Integrator for IMS and CICS (also known as "COMTI") is one
application that commonly uses Syncpoint for 2-phased commit.
Additional query words:
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Keywords : kbsna300sp1 kbsna300sp2 kbsna300sp3 kbsna300sp4 sna4 kbsna400sp1 kbsna400sp2
Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ300SP2 kbSNAServ300SP4
Version : WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Issue type : kbinfo
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