Application Development Guide

Multisite Update with DB2 Connect

DB2 Connect allows you to perform a multisite update, also known as an update of multiple databases within a single distributed unit of work (DUOW). Whether you can use this capability depends on several factors:

• Your application program must be precompiled with the CONNECT 2 and SYNCPOINT TWOPHASE options.

• If you have SNA network connections, you can use two-phase commit support provided by the DB2 Syncpoint Manager (SPM) function of DB2 Connect Enterprise Edition Version 6 on AIX, OS/2, and Windows NT. This enables the following database servers to participate in a distributed unit of work:

  • DB2 Universal Database for AS/400 Version 3.1 or later

  • DB2 for MVS/ESA Version 3.1 or later

  • DB2 Universal Database for OS/390 Version 5.1 or later

  • DB2 for VM & VSE Version V5.1 or later.

  The above is true for native DB2 Universal Database applications and applications coordinated by an external Transaction Processing Monitor such as IBM TXSeries, CICS for Open Systems, Encina Monitor, and Microsoft Transaction Server.

• If you have TCP/IP network connections then the following database servers can participate in a distributed unit of work:

  • DB2 Universal Database for OS/390 V5.1 or later.

  If the application is controlled by a Transaction Processing Monitor such as IBM TXSeries, CICS for Open Sytems, Encina Monitor, or Microsoft Transaction Server, then you must use the DB2 Syncpoint Manager. With DB2 Universal Database Version 6 (including DB2 Universal Database Enterprise Edition, DB2 Enterprise - Extended Edition, and DB2 Connect Enterprise Edition), the DB2 Syncpoint Manager has been enhanced to support TCP/IP connections.

  If the application is a native DB2 UDB application, then the DB2 Syncpoint Manager is not required for two phase commit.

  If a common DB2 Connect EE gateway is used by both native DB2 applications and TP Monitor Applications to access host data over TCP/IP connections then the DB2 Syncpoint Manager must be used.

Note:

If a single DB2 Connect Enterprise Edition gateway will be used to access host data using both SNA and TCP/IP network protocols and two phase commit is required, then the DB2 Syncpoint Manager must be used. This is true for both DB2 applications and TP Monitor applications.

Notes:

1. DB2 Common Server Version 2.1 databases can be updated with two-phase commit in a unit of work only when DB2 Universal Database for OS/390 Version 5.1 is not the transaction manager database.

2. If the TM_DATABASE for the transaction is DB2 Universal Database for OS/390 Version 5.1, then DB2 CS V2.1 databases participating in that transaction become READ-ONLY for the client application.

3. DB2 Universal Database Version 6 client applications can participate in distributed units of work with different levels of database server only if DB2 Universal Database for OS/390 Version 5.1 is the TM_DATABASE for the transaction. For further information refer to either DB2 Connect Enterprise Edition for OS/2 and Windows NT Quick Beginnings, or DB2 Connect Personal Edition Quick Beginnings.

4. The database levels supported for two-phase commit transactions over TCP/IP depend on the DB2 client level, the TM_DATABASE level, and the participant database levels.

   We strongly recommend that all clients accessing DB2 Universal Database Version 6 and DB2 Universal Database for OS/390 Version 5 databases be at DB2 Universal Database Version 6. DB2 Version 2.1 clients cannot initiate two-phase commit transactions if DB2 Universal Database for OS/390 Version 5 databases participate in the transaction.

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