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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: TransactionManagerFactory and WAS (was: [VOTE] publish openjpa 0.9.5-incubating podling release)
Date Thu, 19 Oct 2006 00:50:35 GMT
I think that there are a few issues being discussed here.

1. Best practice for OpenJPA when running with servers/containers  
implementing the TransactionSynchronizationRegistry is to use this  
interface to register for transaction events of interest. There is a  
well-known JNDI name for the instance that implements the interface  
when running in a standard Java EE 5 environment. So this should be  
done in preference to other proprietary mechanisms.

But this interface is not guaranteed to be available if running in  
older servers. In particular, AFAIK, Websphere does not yet ship a  
product that implements this interface. So,

2. For pre-TSR servers, what do we do? Best practice here is to use  
the proprietary mechanisms of the servers, but do so in a way that  
does not require the implementation to be dependent on the  
proprietary interfaces unless running in that environment.

3. I don't see an issue using proprietary (public, documented)  
interfaces as an alternative to TSR. This is a time-honored way to  
get what you need given what is available.

I've just looked at the implementation of *ManagedRuntime in the  
org.apache.openjpa.ee package and found best practice 2 to be  
implemented. Nice job, Marc (attribution in code).

Using TSR will require a non-trivial change to the classes in the  
package. In particular, there will need to be a definition of an  
interface that performs the required registrations without a real  
implementation of TransactionManager.

I don't believe that this is a reason to hold up the release. I hope  
we will be supporting pre-Java EE 5 servers for several years to come.

Craig

On Oct 18, 2006, at 3:39 PM, Marc Prud'hommeaux wrote:

> Kevin-
>
> On Oct 18, 2006, at 2:43 PM, Kevin Sutter wrote:
>
>> -0
>>
>> Although it looks like you already have the three +1 votes to  
>> publish the
>> 0.9.5 release, I'm hesitant with this publish since the current  
>> OpenJPA
>> implementation is using internal WebSphere methods.  I knew about the
>> problem of not using the TransactionSynchronizationRegistry interface
>> (OPENJPA-61), but I didn't realize the implications of using internal
>> WebSphere methods to get around this issue.  Specifically, OpenJPA  
>> is using
>> the following method:
>>
>> com.ibm.ws.Transaction.TransactionManagerFactory.getTransactionManage 
>> r
>
> Is this a problem because you would like to see OpenJPA using more  
> modern methods of getting at the TM, or because there are other  
> serious consequences to calling this method? Note that Kodo has  
> been using this method fine for years, and it looks like a number  
> of other popular frameworks (Spring, Castor, and Hibernate, after  
> some quick Googling on the method name) also use this method to get  
> the WAS TM, so it doesn't seem uncommon.
>
>> I would like to see this get resolved before we publish the 0.9.5  
>> release.
>> The OPENJPA-61 report has two aspects to it.  One is to use the  
>> new JTA
>> interface for Java EE 5 compliant environments.  That's one  
>> problem.  But,
>> the other, more immediate, problem is to remove the usage of internal
>> WebSphere methods for existing WebSphere environments.  We will  
>> attempt
>> resolve this immediate problem first.  And, then worry about the
>> TransactionSynchronizationRegistry.
>
> If it is just a matter of using a more modern method to get the  
> same TM functionality, then we can pretty quickly implement this by  
> adding a new WASManagedRuntime that gets the TM in whatever way we  
> want. However, if it doesn't work with older WAS versions, we  
> should keep the old method around as well, since otherwise people  
> won't have any way of integrating with this version.
>
> Ideally, of course, everything would move towards the  
> TransactionSynchronizationRegistry, but as I mentioned in  
> OPENJPA-61, we currently rely internally on having a  
> javax.transaction.Transaction instance for both managed and stand- 
> along transactions. The quickest route to getting this to work  
> would be to make some  
> TransactionSynchronizationRegistryTransactionManagerFacade that  
> returns a TransactionFacade implementation of  
> javax.transaction.Transaction whose begin()/commit() methods are  
> just no-ops or throw exceptions (since I don't think the Broker  
> should ever be calling those methods when the  
> "openjpa.TransactionMode" is set to "managed").
>
> However, I haven't yet experimented with a container that supports  
> the TransactionSynchronizationRegistry, so that implementation work  
> would be best done by someone who has experience with one of those  
> containers (hint :)
>
> Anyway, in conclusion, I'm happy to see an update to the methods  
> through which the transaction integration is performed provided we  
> don't break backwards compatibility with older versions. I'd also  
> rather not hold up 0.9.5 just for this ... we can always cut a new  
> release pretty quickly once we get the updated integration working  
> and tested, but in the near term, it'd be nice to get something out  
> there beyond the nightly snapshots that people can start relying on.
>
>
>> Thanks,
>> Kevin
>>
>> On 10/18/06, Abe White <awhite@bea.com> wrote:
>>>
>>> +1
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>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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