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From Brian McCallister <mccallis...@forthillcompany.com>
Subject Re: OTM + Connections/Transactions
Date Mon, 29 Sep 2003 12:56:18 GMT
Responding to myself as I don't want the thread to die...

Thoughts on this anyone? I am the new guy, so want to make sure I *do* 
understand the plan.


On Wednesday, September 24, 2003, at 02:28 PM, Brian McCallister wrote:

> On Wednesday, September 24, 2003, at 01:07 PM, Raghuram Rajah wrote:
>> Hi Oleg/Brian,
>> The reason for registerConnection taking a BaseConnection and not an
>> OTMConnection is this. Many environments do not to support arbitrary
>> association of connections to transactions.
> In these environments, specifically disable it via an 
> OperationNotSupported exception.
>> So, IMHO, exposing the
>> registerConnection is a bad idea. The only environment where this 
>> makes
>> sense is a j2se environment. The correct way to implement that is to 
>> create
>> a new TransactionFactory.
> I disagree. Multiple connections can in fact be used in a J2EE 
> environment -- it is just trickier. It cannot easily be done in a 
> clustered environment unless the Transaction is migratable and only 
> accessed on a single node at a time.
> However, I think disallowing arbitrary associations because it doesn't 
> work easily on a minority environment is not a good idea. If it needs 
> to be disabled in a specific environment, that environment is the 
> exception, not the rule.
> The stated design goal to allow 1:M Transaction:Connection 
> relationships is most easily accomplished form the User perspective by 
> allowing the attachment of a Connection to a Transaction, particularly 
> as that behavior is already somewhat exposed. Do not expose methods on 
> a the published API (the OTMConnection and Transaction interfaces 
> respectively) that the user isn't able to use. It causes chaos and 
> confusion.
> Requiring Connections be obtained from a specific factory is okay to 
> me, as obtaining the Connection and attaching it to a Transaction 
> before using it is the required behavior for this. However, if we are 
> going to do it that we we need to do it that way, and we need to 
> expose a mechanism in the factory interface to do this. Either way, 
> the ability needs to be exposed somehow. Based on the present API, it 
> should be exposed on the Kit, Connection, or Transaction. As 
> Connections and Transactions are required to be aware of each other 
> presently, exposing it at that level (as compared to hiding it in the 
> Kit) is okay.
> I am looking at this from the OJB user perspective..
> Kit.acquireConnection(pbKey, transaction) works fine for me, 
> Transaction.registerConnection(OTMConnection) works for me as well. 
> Heck, Connection.setTransaction(Transaction) works fine too. A good 
> case can be made for putting it on the Kit and hiding the 
> registerConnection() method (remove it from Transaction entirely) in 
> that registerConnection() and setTransaction() would need to invoke 
> each other in practice since each needs to know about the other (I 
> think it could be done with a Transaction not knowing about 
> Connections using it as it is an object-level transaction - it just 
> needs to provide services to the Connection) but it isn't done that 
> way at the moment.
> -Brian
> (all of this said, I do *really* like the OTM, I just want more ;-)
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