通过多个数据源进行事务管理

Question

If we are performing a transaction using a datasource (named 'ABC') and inside that transaction we need a different connection object from other datasource (named 'DEF')

So what we are currently doing is, we set the @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED) on the EJB method, In the same method we are writing the code for getting the new connection from other datasource (named 'DEF').

The reason why we are doing this is 'There is transaction going on that is using a connection from datasource named 'ABC', but now we need to perform some other operation in other transaction so we need a connection from other datasource named 'DEF', that is why we need to suspend the first transaction by saying NOT_SUPPORTED and do the necessary operation on the new connection and then again resume the same old transaction'

Please validate my understanding.

Answer 1

TransactionAttributeType.NOT_SUPPORTED is not what you need, if I understand your scenario correctly.

You need to annotate the method with TransactionAttributeType.REQUIRES_NEW . This will suspend the outer transaction and create a new independent transaction.

Answer 2

You're reasoning is sound. If you're using Spring, there is a more simple way:

@Transactional( "DEF", propagation: Propagation.NESTED )

This will create always create a new transaction using the TransactionManager DEF

Unfortunately, the EJB standard doesn't support NESTED .

Answer 3

Transactions can be classified into two categories

1. Local Transaction -- single unit of work in single database.
2. Global Transaction --- single unit of work deals with more than one database.

For more details refer J2EE online documents..

Cheers!