From: Jeremy Quinn > The problem arises when you wish to use a (brilliant) feature of > Hibernate called 'lazy-initialisation', whereby access to the DB is > only made when you actually ask for Bean Properties. > > This is particularly useful when you have large 'graphs' of related > Beans, for instance child/parent relationships, whereby loading one > Bean may result in the whole database loading!! > > If you have closed your Hibernate Session in your Flowscript, your > display layer can throw LazyInitialisationExceptions, because the > connection is no longer available. > > Not closing the Session after you have sent the Response, is > considered > bad practise, so the Servlet Filter is a handy solution.
It's a pity that Hibernate is under LGPL - this would be a great example ... Have the Hibernate people ever been asked if they would put their great piece of software under a more Apache like licence? As I'm curious I have a technical question: What's the difference if I read the necessary data in the flow or some milliseconds latter in the view layer? What do I gain? > >> However, with the generous assistance of Ugo Cei, I am > successfully > >> using the technique highlighted in the first sample here [1] for > >> managing Hibernate Sessions in my FlowApp. > >> > >> The basic issue is that you want to avoid maintaining an open > >> Hibernate Session whilst the user is interacting with a > form (etc.). > >> The Session > >> should to be opened and closed during each Request (and any > >> Transient > >> Beans refreshed before re-use). The above technique uses a Servlet > >> Filter to manage this, with a static method to retrieve a > Session in > >> your flowscript at the beginning of each Request that needs it. > >> > >> [1] http://hibernate.bluemars.net/43.html > >> > > > > Sounds cool and I remember that I've already heard from it > but haven't > > found the time to try it myself. > > I am using it ATM on a client project and it is a dream! > > > <dream-mode> > > I would like to use this Avalon component mentioned above and the > > Flow interpreter takes care of releasing (and providing) stateful > > components within my scripts. So I would have to lookup > the Hibernate > > Session at the beginning(2) and until I finally release(8) > it I don't > > have to take care for it. > > > > 1 function xxx() { > > 2 var hibS = cocoon.getComponent( "hibernateSession" ); > > 3 var custBean = hibS.blablabla // get your beans with hibernate > > 4 sendPageAndWait( "bla", {customer : custBean} ); > > 5 // do something (updates, reads, whatever) > > 6 var someDifferentBean = hibS.blalbalba > > 7 sendPageAndWait( "bla", {diff : someDifferentBean } ); > > 8 sendPageAndRelease( "thankYou", {} ); > > 9 } > > > > This would be IMO a very elegant way and IIU the recent > discussion > > correctly possible from a technical point of view. Maybe Chris can > > comment on this :-) > > > > Thoughts? > > This is a reality! > Wake up and smell the toast ;) ;-) > > I just do not use the Component Manager, because I cannot manage the > Hibernate Session entirely from the FlowScript layer as explained > above. I have a static method that gives me a fresh Session. I get s > Session at the beginning of Function, or directly after a > sendPageAndWait(). Is it possible to have a look at the sources? I would be very interested! Cheers, Reinhard
