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From David Jencks <>
Subject Re: Geronimo Transaction manager
Date Mon, 23 Feb 2009 18:26:00 GMT

On Feb 23, 2009, at 10:13 AM, Juergen Weber wrote:

> djencks wrote:
>>> So, even if it cannot be used as OTS, can the Geronimo Transaction
>>> service
>>> be used from outside of Geronimo?	
>> Geronimo TM just does xa but does not try to do OTS.  It does do
>> transaction import so the main obstacle to distributed xa  
>> transactions
>> (i..e. more than one transaction manager participating in a tx) is  
>> the
>> lack of a transport mechanism between tms.
> Well, sorry, I mis-formulated, by "outside of Geronimo" I meant  
> using the TM
> running in Geronimo over the network to control data base operations  
> in
> another process.
> So, I guess one would need an OTS transport mechanism. Do you think  
> it would
> be difficult to expose the Geronimo TM as OTS service?

Despite studying the OTS spec for some time I didn't understand it  
well enough to come up with a guess at how hard it would be to  
implement or whether it would be easier to wrap an XA tm or start  
over.  It's been several years since I looked at this.  In the  
unlikely event that I remember correctly, if an OTS wraps an XA tm you  
will end up running a copy of the XA tm on the node that is doing the  
work on the database anyway as a manager for the tx branches for that  
node so IMO you might as well just use the xa tm on that node to start  
with.  As I said I don't remember very well how this is supposed to  

Could you explain in more detail what you are trying to do?

> djencks wrote:
>> trunk includes j2ca connector 1.6 spec code which doesn't really  
>> alter
>> the tm at all but has some other nice features.
> Do you mean Transaction Inflow (cited in the slides linked here:
> ?

Transaction inflow has been present since connector 1.5, although its  
implemented a little differently in 1.6.  It certainly seems like a  
possible foundation for constructing distributed transactions.   
However, I've yet to find anyone who knows anyone who is using  
distributed transactions in production.  (just to reiterate, by  
distributed tx I don't mean an xa tx with more than one resource  
manager, but a transaction with more than one transaction manager  

david jencks

> Thanks very much for you explanations,
> Juergen
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