Transaction propagation

[mettus]

Hi,
I have a jar file for data access. it manages the transactions using Spring. i use GenericApplicationContext to load beans and transaction information.

This jar file is used in many web applications, that doesn't initiate any transactions, to access and update data.

Now if i build a new web application using struts MVC or spring MVC that initiates its own transactions, is it possible for the jar file data access objects to participate in that tranaction instead of their own tranaction.

I am new to Spring! i really appreciate your help.

Thanks,
-Mettu.

[marius]

One solution that I see right now is to use POJO wrappers over your "jar" objects, and make these POJO's to participate in a transaction e.g thourgh TransactionProxyFactoryBean.

[mettus]

Hi Marius,
Thanks for the reply! these are the layers i have in jar file
Service layer - which is accessed by web applications
- relies on Broker layer for actual database operations
Broker Layer - does actual database access and update work.
i defined the transactions at Broker level in the jar file.

Now can the Broker layer participate in the existing transaction if the web application makes the service layer participate in the transaction that initiates?

Please let me know if i got it right.

Thanks,
-Mettu.

[marius]

... these are the layers i have in jar file
Service layer - which is accessed by web applications
- relies on Broker layer for actual database operations
Broker Layer - does actual database access and update work.
i defined the transactions at Broker level in the jar file.

Now can the Broker layer participate in the existing transaction if the web application makes the service layer participate in the transaction that initiates?

Please let me know if i got it right.

Thanks,
-Mettu.

Here is how I see things:

1. Make a POJO and wrap it around your Service layer.
2. Make it transactional (very important).
3. If your Broker layer throws an exception (e.g. SQLException) and it propagates up to your POJO, hence you don't catch it or rethrow it out of your POJO (or mark it as rolleBackOnly), transaction started by Spring AOP will be automatically rolledback therefore all participats to this transaction will be rolledback.

On the other hand, If you don't get any exception out of your Service layer due to an exception from Broker layer (e.g. SQLException) and there is no way to know if JDBC operations from Broker layer failed, then I'm not sure how you can you make it participate to Spring transaction. It might be possible though if you're using DataSource's and somehow make it use a Spring defined DataSource.



I hope that helps.

[marius]

I forgot to mention about one other thing. If some other participant of the transaction causes a rollback, and you want your broker to also rollback, then I guess DataSource from Broker needs to be know by Transaction Manager (That of course in case that you're using DataSource and you're not doing "manual" commit)