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From Jules Gosnell <>
Subject Re: -1 on checkin of 368344 was Re: [wadi-dev] Clustering: WADI/Geronimo integrations.
Date Thu, 12 Jan 2006 17:16:39 GMT
Jeff Genender wrote:

>I didn't finish #4..sorry...
>4) Your integration of setting the manager (no matter what) is a direct
>clash with the Tomcat clustering components (GBeans).  We need a more
>unified approach to selecting a clustering component.
OK - this is finally a useful point.

Questions :

- does my change prevent the use of alternative Tomcat clustering 
components ?
- if so, how - I will fix it ?


>Jeff Genender wrote:
>>Hi Jules.
>>A few comments.  First, you made changes without discussing them on the
>>dev lists.
>>As per the discussions in the past, both Aaron and David Jencks, as well
>>as I threw in our .02 on how to integrate the clustering.  I would
>>appreciate you discuss code ideas and changes that have such a drastic
>>impact on the Geronimo code base.  Here are the issues with your check in:
>>1) I explained before for Jetty, and obviously now I need to do it for
>>Tomcat, a -1 on Axion as a dependency.  There should not be any web
>>application dependencies injected at the container level.  This means
>>there is a severe architectural issue with WADI when we are injecting
>>these dependencies into the container.
>>2) You hard coded in org.codehaus.wadi.tomcat55.TomcatManager as the
>>distributablesession manager in the TomcatContainer.  Hardcoding a
>>pluggable session engine is very bad, and defeats the pluggability of a
>>configuration that we requested.
>>3) You placed in the code, and Aaron worked pretty hard to
>>clean those up.
>>4) Your integration of setting the manager (no matter what) is a direct
>>clash with the
>>Jules, I am giving a complete -1 of checkin of 368344.  These are all
>>for technical reasons.  Please back out these changes, and bring this
>>discussion to the Geronimo lists as this needs some significant
>>discussion for implementation.  I would appreciate that you please
>>involve the Apache way and open discussions on the lists before doing
>>this sort of thing in the future.
>>Again, I will CC the G lists to make this clear, that I would like this
>>change backed out.
>>Jules Gosnell wrote:
>>>Here is a list of outstanding issues associated with this work:
>>>- ActiveMQ's shutdown hook seems to trigger when Geronimo is shutdown,
>>>removing AMQ before WADI - WADI doesn't like this. I have added a
>>>property to the script which suppresses this behaviour. I will
>>>document it in the Getting Started doc.
>>>- There 'may' be issues with nodes finding each other, when a Geronimo
>>>node is introduced into a WADI cluster - investigating.
>>>- Jeff - you should look over the changes and make sure that they do not
>>>impact on any other TC fn-ality. They were done with Emacs, so the
>>>formatting may be offensive. Please feel free to make them your own and
>>>bring any issues back to the list. The WADIGBean, is no longer used, so
>>>you may want to remove this from the repo.
>>>- Jan and Jeff - since this config is now done on the container bean and
>>>not in the geronimo-web.xml, you may no longer need to implement your
>>>own geronimo-web.xml schemas (I haven't looked very closely at TC). You
>>>may want to consider this and perhaps lose them.
>>>- In order to get the same webapp to work in all containers
>>>(tomcat5[05], jetty[56], geronimo-[tomcat/jetty], jboss-tomcat), I had
>>>to move deps back to Geronimo container-level. These include Axion,
>>>which I know will upset Jeff. As I have stated before, WADI's dependence
>>>on Axion is easily removed. If Jeff or anyone wants to look at replacing
>>>it with Derby, it is fine with me, as long as they do some testing and
>>>confirm that having created a session on a single node and restarted it,
>>>the session survives (if the DB is still running). This needs to be
>>>tested on all supported containers. Axion was used because it is an
>>>in-VM DB (so imposes no further integration dependencies on the Getting
>>>Started stuff and is useful for unit-testing) and was in use by Geronimo
>>>at the time. So I suggest that any replacement needs to also be able to
>>>run in-vm aswell. As we go further and move WADI's actual configuration
>>>from the app to the container-level, these issues will disappear and
>>>WADI will be able to be hooked to whatever persistance mechanism is
>>>shipped in Geronimo by default.
>>>- Jan & Jeff , you may want to consider pushing some of this session
>>>manager selection code up into a shared GeronimoWebContainer abstraction
>>>so that you don't both end up maintaining similar but diverging code...
>>>- I may have overlooked a couple of issues. If I come across them, I
>>>shall post them.
>>>Further work on Geronimo integration :
>>>- more testing
>>>- make a new WADI release and update geronimo-trunk to use it
>>>- look at applying diffs to a G1.0 tree and producing a binary patch for
>>>1.0 distros.
>>>- update website and release it
>>>Jules Gosnell wrote:
>>>>Jan and I have just refactored the Geronimo Jetty and Tomcat
>>>>integrations to take the same approach to the installation of a 3rd
>>>>party session manager, to ease the integration of WADI. This is now
>>>>checked in on Geronimo's trunk.
>>>>Each top level web container GBean now supports a pair of attributes -
>>>>LocalSessionManager and DistributableSessionManager. These may be used
>>>>to override the container's choice of SessionManager for webapps with
>>>>and without the <distributable/> tag present in the WEB-INF/web.xml,
>>>>The attributes expect to be given a classname, if required, this class
>>>>will be loaded and instantiated. The resulting instance will be used
>>>>as the session manager. If not provided, the container will use a
>>>>sensible default. Currently Jetty and TC are set up to use their own
>>>>default session managers in the local case and the correct WADI
>>>>session manager in the distributable case.
>>>>This means that the same WADI-enabled webapp, with its plan held
>>>>internally (WEB-INF/geronimo-web.xml) may now be hot-deployed on
>>>>either a Jetty or a Tomcat based Geronimo, without changes :-)
>>>>I will post specific WADI issues to the WADI dev lists
>>>>This shouldn't be seen as a final position on the subject - there is
>>>>still much to talk about, but is a useful interim step, that allows us
>>>>to have something working whilst we figure out how to go forward.

"Open Source is a self-assembling organism. You dangle a piece of
string into a super-saturated solution and a whole operating-system
crystallises out around it."

 * Jules Gosnell
 * Partner
 * Core Developers Network (Europe)
 * Open Source Training & Support.

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