DJ, Thanks for beginning this thread...I think this is a great forum to discuss it.
My discomfort with the changes is I think it placed it in a worse state than we had it. Again, its my discomfort and wish to stand by my -1 on it. I cannot equate this to your checkins David, because you typically do have a fair amount of open discussion into what you are doing before making the change. History will attest to that ;-) With that said, lets use this thread to move forward this discussion..so I am glad its here. So lets start with the big question... How do we want to see a clustering component integrated? Do we want this from a configuration/assembly level that allows for an import of this at a plan level? Whats the best way to allow injection at the container level, the host level, and the context level? How do we support multiple clustering components taht have many configuration options? Thanks, Jeff David Jencks wrote: > I agree with Jeff that this change is unsatisfactory but I'm not as sure > as he is that backing it out is necessary, perhaps we can move forward > to an acceptable solution instead. > > I also am not so sure that this magnitude of change needs prior > discussion on the list. I've frequently made larger changes without > discussion of my specific code. I've also broken lots of stuff at > various times. > > One thing I insist on is that it be possible to run geronimo with no > clustering support whatsoever, including no clustering classes anywhere > in the geronimo system. I believe this means that each clustering > system has to be installed as a configuration. Doing this right now as > the first step will I think help focus the rest of the componentization. > > I don't understand the requirements very well, I hope for some answers: > > - do we need to support running more than one clustering system with a > particular web container instance (e.g. JettyContainerImpl gbean > instance)? I'm hoping "no" > > IIUC we are installing clustering as a session manager. Perhaps I don't > understand the code but it looks to me as if the jetty code at least is > creating a new instance for each web app. I can't believe this is an > acceptable strategy for all clustering implementations. For instance, I > would think if you have a bunch of web apps doing cross-context dispatch > you would want them all to share a session manager. I think we want the > possibility of installing a single container wide session manager or > per-app session managers. > > Is it really plausible to rely on the distributable tag in the spec dd > to turn on clustering? I would think a further tag in our plan should be > needed. > > Here's what I propose: > > We define a SessionManagerFactory interface, and for each clustering > technology provide an implementation as a gbean. You can get a local > and a distributed session manager from this interface. The runtime > configuration for the clustering includes this gbean. Each web app > context gets a reference to this gbean and gets the appropriate session > manager when it starts. The web app context knows if it is supposed to > be local or distributed so it can ask for the right session manager. > > We have a deploy time configuration for each clustering technology > also. This at least supplies the gbean reference to the runtime gbean, > and can also install a runtime gbean in the configuration under > construction. In this way the clustering technology can decide on > whether one session manager is shared, a factory that always returns > unconfigured new instances is needed, or if each web app needs a > specially configured session manager. > > > > If this isn't clear, I'll be happy to try to clarify. > > thanks > david jencks > > > On Jan 12, 2006, at 7:54 AM, 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. >> >> 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 log.info() 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. >>> >>> Jeff >>> >>> >>> 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 node.sh 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 >>>> >>>> >>>> >>>> Jules Gosnell wrote: >>>> >>>>> Guys, >>>>> >>>>> 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, >>>>> respectively. >>>>> >>>>> 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 >>>>> ([email protected], [EMAIL PROTECTED]). >>>>> >>>>> 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. >>>>> >>>>> Enjoy, >>>>> >>>>> >>>>> Jules >>>>> >>>>
