I am using Hivernate 2.0 and weblogic 6.1 sp1.
The hibernate.properties file:

hibernate.dialect=net.sf.hibernate.dialect.DB2Dialect
hibernate.connection.datasource=meta_db2
hibernate.show_sql=true
hibernate.transaction.factory_class=net.sf.hibernate.transaction.JTATransactionFactory
hibernate.transaction.manager_lookup_class=net.sf.hibernate.transaction.WeblogicTransactionManagerLookup

meta_db2 is an jndi datasource name registered in weblogic.

The mapping file for Task Entity:
<hibernate-mapping>
<class
name="com.volcano.metadata.model.TaskEntity"
table="ELEMENT_TASK"
dynamic-update="false"
dynamic-insert="false"
>
<id
name="id"
column="id"
type="long"
>
<generator class="hilo">
</generator>
</id>
...
<set
name="taskParameters"
table="SCHEDULER_TASK_PARAMETER"
lazy="false"
inverse="false"
cascade="save-update"
sort="unsorted"
>

<key
column="TASK_ID"
/>
<composite-element class="com.volcano.metadata.model.TaskParameterEntity">

<many-to-one name="parameter"
class="com.volcano.metadata.model.ParameterEntity"
cascade="none"
outer-join="auto"
update="true"
insert="true"
column="PARAMETER_ID"
not-null="true"
/>
<property
name="sequence"
type="int"
update="true"
insert="true"
column="SEQUENCE"
/>

<property
name="parameterValue"
type="java.lang.String"
update="true"
insert="true"
column="PARAM_VALUE"
length="100"
/>
</composite-element>

</set>
...
</hibernate-mapping>

I need to delete a task for an id from a SLSB:
public void removeTask(long id ) throws
Exception {

Session session = null;
try {
session = sessionFactory.openSession();
Task task = ( Task )session.load( TaskEntity.class, new Long( id ) );
session.delete(task);
session.flush();
} catch( Exception e ) {
sessionContext.setRollbackOnly();
throw ...
} finally {
session.close();
}
}

When I delete a task which have several parameters, the hibernate first delete the relation table, and then delete the task table:

Hibernate: delete from SCHEDULER_TASK_PARAMETER where TASK_ID=?
Hibernate: delete from ELEMENT_TASK where id=?
16:19:59,000 WARN JDBCExceptionReporter:36 - SQL Error: -532, SQLState: 23504

An Exception occur when delete a task, then all parameters of the task in SCHEDULER_TASK_PARAMETER table will be delete!!! Why the transaction did not rollbak although i called sessionContext.setRollbackOnly() when catching Exception?

This is certainly an issue with either your transaction demarcation or the definition of your data source.

Make sure, for example, that the driver is not set to specify connections as auto-commit. Make sure in the WL console that your "meta_db2" datasource is defined as a TxDataSource and not just a plain DataSource. Also, make sure that a transaction is actually in effect when entering this method.

I change the plain DataSource to TxDataSource. Then the transaction works correctly. Thanks for your reply so quick!!!

How do you define a datasource as a TxDataSource?
I'm using JBoss 3.2.3.

There are two kinds of datasource in WLS, one is plain DataSource, another is TxDataSource. Only TxDataSouce can participate in CMT. Maybe it is a specialization of WLS. I did not find that kind of DataSource in WebSphere too.