Programming WebLogic JTA
Using Third-Party JDBC XA Drivers with WebLogic Server
This section discusses the following topics:
- Overview of Third-Party XA Drivers
- Using Oracle Thin/XA Driver
- Using Sybase jConnect 5.5 and 6.0/XA Drivers
- Using Other Third-Party XA Drivers
Overview of Third-Party XA Drivers
This section provides an overview of using third-party JDBC drivers with WebLogic Server in distributed transactions. These drivers provide connectivity between WebLogic Server connection pools and the DBMS. Drivers used in distributed transactions are designated by the driver name followed by /XA; for example, Oracle Thin/XA Driver.
Table of Third-Party XA Drivers
The following table summarizes known functionality of these third-party JDBC/XA drivers when used with WebLogic Server:
Table 10-1 Two-Tier JDBC/XA Drivers Driver/Database Version Comments Oracle Thin Driver XA See Using Oracle Thin/XA Driver. Sybase jConnect/XA
- Version 6.0
- Version 5.5
- Adaptive Server Enterprise 12.0
See Using Sybase jConnect 5.5 and 6.0/XA Drivers.
Using Oracle Thin/XA Driver
WebLogic Server ships with the Oracle Thin Driver version 10g preconfigured and ready to use. If you want to update the driver or use a different version, see “Using Orace Extensions with the Oracle Thin Driver” in Programming WebLogic JDBC.
The following sections provide information for using the Oracle Thin/XA Driver with WebLogic Server.
Software Requirements for the Oracle Thin/XA Driver
The Oracle Thin/XA Driver requires the following:
- Java 2 SDK 1.4.x or later.
The Oracle 10g and 9.2 Thin driver (ojdbc14.jar) are the only versions of the driver supported for use with a Java 2 SDK 1.4.X.
- Oracle server configured for XA functionality (limitation does not apply for non-XA usage).
Set the Environment for the Oracle Thin/XA Driver
Configure WebLogic Server
See “Using Oracle Extensions with the Oracle Thin Driver” in Configure WebLogic JDBC.
Enable XA on the Database Server
To prepare the database for XA, perform these steps:
- Log on to sqlplus as system user, e.g. sqlplus sys/CHANGE_ON_INSTALL@<DATABASE ALIAS NAME>
- Execute the following command: @xaview.sql
The xaview.sql script resides in the $ORACLE_HOME/rdbms/admin directory
- Grant the following permissions:
- grant select on v$xatrans$ to public (or <user>);
- grant select on pending_trans$ to public;
- grant select on dba_2pc_pending to public;
- grant select on dba_pending_transactions to public;
- (when using the Oracle Thin driver 10.1.0.3 or later)
grant execute on dbms_system to <user>;If the above steps are not performed on the database server, normal XA database queries and updates may work fine. However, when the Weblogic Server Transaction Manager performs recovery on a re-boot after a crash, recover for the Oracle resource will fail with XAER_RMERR. Crash recovery is a standard operation for an XA resource.
Oracle Thin/XA Driver Configuration Properties
The following table contains sample code for configuring a JDBC data source:
Using Sybase jConnect 5.5 and 6.0/XA Drivers
The following sections provide important configuration information and performance issues when using the Sybase jConnect Driver 5.5 and 6.0/XA Drivers:
- Configuring a Sybase Server for XA Support
- XA and Sybase Adaptive Server
- Configuration Properties for Java Clients
- Known Sybase jConnect 5.5 and 6.0/XA Issues
Configuring a Sybase Server for XA Support
Follow these instructions to set up the environment on your database server:
- Run sp_configure "enable DTM",1 to enable transactions.
- Run sp_configure "enable xact coordination",1.
- Run grant role dtm_tm_role to <USER_NAME>.
- Copy the sample xa_config file from the SYBASE_INSTALL\OCS-12_0\sample\xa-dtm subdirectory up three levels to SYBASE_INSTALL,where SYBASE_INSTALL is the directory of your Sybase server installation. For example:
$ SYBASE_INSTALL\xa_config- Edit the xa_config file. In the first [xa] section, modify the sample server name to reflect the correct server name.
To prevent deadlocks when running transactions, enable row level lock by default:
- Run sp_configure "lock scheme",0,datarows
Both the jConnect.jar, jconn2, and jconn3.jar files are included in the WL_HOME\server\lib folder and are referenced in the weblogic.jar manifest file. When you start WebLogic Server, the drivers are loaded automatically and are ready to use with WebLogic Server. To use these drivers with the WebLogic utilities or with other applications, include the path to these files in your CLASSPATH.
XA and Sybase Adaptive Server
Correct support for XA connections is available in the Sybase Adaptive Server Enterprise 12.0 and later versions only. XA connections with WebLogic Server are not supported on Sybase Adaptive Server 11.5 and 11.9.
Execution Threads and Transactions in Sybase Adaptive Server
Prior to Adaptive Server version 12.0, all resources of a transaction were privately owned by a single task on the server. The server could not share a transaction with any task other than the one that initiated the transaction. Adaptive Server version 12.x includes support for the suspend and join semantics used by XA-compliant transaction managers (such as WebLogic Server). Transactions can be shared among different execution threads, or may not be associated with an execution thread (detached).
Setting the Timeout for Detached Transactions
On the Sybase server, you can set the dtm detach timeout period, which sets the amount of time (in minutes) that a distributed transaction branch can remain in the detached state (without an associated execution thread). After this period, the DBMS automatically rolls back the transaction. The dtm detach timeout period applies to all transactions on the database server. It cannot be set for each transaction.
For example, to automatically rollback transactions after being detached for 10 minutes, use the following command:
sp_configure 'dtm detach timeout period', 10You should set the dtm detach timeout period higher than the transaction timeout to prevent the database server from rolling back the transaction before the transaction times out in WebLogic Server.
For more information about the dtm detach timeout period, see the Sybase documentation.
Transaction Behavior on Sybase Adaptive Server
If a global transaction is started on the Sybase server, but is not completed, the outcome of the transaction varies depending on the transaction state before the transaction is abandoned:
- If the client is terminated before the xa.end call, the transaction is rolled back.
- If the client is terminated after the xa.end call, the transaction remains on the database server (and holds all relevant locks).
- If an application calls xa.start but has not called xa.end and the application terminates unexpectedly, the database server immediately rolls back the transaction and frees locks held by the transaction.
- If an application calls xa.start and xa.end and the application terminates unexpectedly, the database server rolls back the transaction and frees locks held by the transaction after the dtm detach timeout period has elapsed. See Setting the Timeout for Detached Transactions.
- If an application calls xa.start and xa.end, and then the transaction is prepared, if the application terminates unexpectedly, the transaction will persist so that it can be properly recovered. The Transaction Manager must call rollback or commit to complete the transaction.
Configuration Properties for Java Clients
Set the following configuration properties when running a Java client.
Known Sybase jConnect 5.5 and 6.0/XA Issues
These are the known issues and Oracle workarounds:
Using Other Third-Party XA Drivers
To use other third-party XA-compliant JDBC drivers, include the path to the driver class libraries in your CLASSPATH and follow the configuration instructions provided by the vendor.