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From "Hiram Chirino" <hi...@hiramchirino.com>
Subject Re: [Discussion] Removal of TransactionContextManager
Date Thu, 03 Aug 2006 19:10:41 GMT
+1 great job dain.  This is a great move toward making geronimo
components more decoupled and more re-usable.

On 7/31/06, Dain Sundstrom <dain@iq80.com> wrote:
> <history length="too long">
> About a week ago there was a discussion on the OpenEJB mailing list
> regarding the TransactionContextManager.  In OpenEJB 3 we removed the
> use of the TCM from Geronimo and replaced it with just a
> javax.transaction.TransactionManager.  This brought all of the
> openejb containers into alignment.  The other big motivation was to
> ease the integration of OpenEJB and third part libraries,
> specifically Spring.  The problem with the TCM is that if you use it
> you can't use the TM directly since the TCM needs to know about all
> TM calls.  Additionally, to use the TCM you must demarcate all
> changes in "component context" by starting an unspecified transaction
> context.  This is all quite invasive and made OpenEJB hard to use in
> Spring or plain old Tomcat.
>
> That was all fine and good for OpenEJB 3, but as it turns out there
> is a desire to keep the OpenEJB 2 and 3 code aligned as much as
> possible, so a discussion started around how to backport the changes
> to 2.  We determined there were two options:
>
> 1) wrap the TCM with a class that implements TM but delegates to the
> TCM - this would be tricky to get working and there is always the
> problem of demarcating the unspecified transaction context
>
> 2) remove the TCM from Geronimo entirely - this could be a lot of work
>
> After a quick look at the first option, I decided to try option two.
> It turned out to be a lot easier than I thought since, the biggest
> user of TCM was OpenEJB and I had already pulled it out of OpenEJB.
> I also think I have become the master of using the IntelliJ refactor
> tools and was able to remove the code without too much hand tweaking.
> </history>
>
> I have checked the fruits of this effort into https://svn.apache.org/
> repos/asf/geronimo/branches/dain/notcm and there is a matching
> OpenEJB branch that is checked out with maven m:co.  I have not
> updated the m2 build yet, as it was finalized during this work.
>
> For those of you that are following the Jencks project, which wraps
> the Geronimo transaction and connector modules with Spring bean
> factories, I have created a branch there also, which contains a
> massive simplification due to the refactors in the removal of the
> Geronimo TCM.  Here are some fun examples from that project:
>
> http://fisheye.codehaus.org/browse/jencks/branches/notcm/src/test/
> resources/org/jencks/samples/outbound/jencks-tranql.xml?r=112
> http://fisheye.codehaus.org/browse/jencks/branches/notcm/src/test/
> resources/org/jencks/spring-request-reply-jta.xml?r=112
>
> So what does everyone think about removing the TCM in general?  After
> that I think we may want to discuss the specifics of my branch.  I
> may have gotten too refactory happy :)  Details on the specific
> changes I made follow:
>
> TransactionContextManager
> -------------------------
> Removed TransactionContextManager and replaced all uses with a plain
> old TransactionManager
> Removed all code from web containers, app client and timer that was
> simply demarcating an unspecified transaction context, which is no
> longer needed
>
> TransactionManager
> ------------------
> Merged XATerminator portion of TCM into GeronimoTransactionManager
> which is a subclass of TransactionManagerImpl
> Improved tx thread association code so we can throw an error if
> someone attempts to resume a tx associated with another thread
> Added TransactionManagerMonitor which is used by the connection
> tracker to know when a transaction context has changed
>
> UserTransaction
> ---------------
> TransactionManagerImpl now implements UserTransaction to ease
> integration with third party libraries such as Spring
> Removed OnlineUserTransaction since it was only really used by
> OpenEJB and it has it's own UserTransaction implementation
> Web containers now use GeronimoUserTransaction which is an always on
> wrapper around a transaction manager
>
> Third party support
> -------------------
> Moved use of ServerInfo from HOWLLog to HOWLLogGBean so it can be
> more easily use by third party libraries
> Moved connector related transaction data to connector module
> Replace use of Geronimo's thread pool with a concurrent executor
>
>
> -dain
>


-- 
Regards,
Hiram

Blog: http://hiramchirino.com

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