persistence@glassfish.java.net

Re: Caching-Between-Transactions

From: Adam Bien <abien_at_adam-bien.com>
Date: Tue, 15 Aug 2006 13:37:27 +0200

Hi Kim,

but this shouldn't be the default bevior. No J2EE developer would expect
such configuration.
In an average Java EE environment (many clients use the same database),
the data could become inconsistent,

regards,

adam
Wonseok Kim schrieb:
>
>
> On 8/15/06, *Adam Bien* <abien_at_adam-bien.com
> <mailto:abien_at_adam-bien.com>> wrote:
>
> Hi Marina,
>
>
> Marina Vatkina schrieb:
> > Hi Adam,
> >
> > Are you asking about CMP or Java Persistence implementation?
> > They are based on 2 different code bases in glassfish ('cmp'
> > and 'entity-persistence' sub-modules).
> >
> > CMP supports version consistency, and as such "caching between
> > transactions" for those beans that choose to use this consistency
> > level. It also supports read-only CMPs which states are cached
> for a
> > period of time (refresh interval).
> >
> > JPA implementation always uses "caching between transactions",
> > and you need to call an explicit refresh, to reload an instance
> > from a database (like you have by default in CMP).
> >
> Really, I would expect, that in every new transaction I would get
> fresh
> data from database?
>
>
> I don't think so. Even in a transaction-scoped persistence context,
> TopLink caches entities in the sesion cache so if you do em.find() you
> will get cached result. You can call em.refresh() after em.find() or
> execute query with query hint "toplink.refresh" to get fresh one from
> database.
> - Wonseok
>
> Thanks,
>
>
>
> adam
> > HTH.
> >
> > Regards,
> > -marina
> >
> > Adam Bien wrote On 08/14/06 08:11,:
> >
> >> I read the following thread:
> >> http://www.theserverside.com/news/thread.tss?thread_id=41748
> <http://www.theserverside.com/news/thread.tss?thread_id=41748>
> >>
> >> Do glassfish not support the notion of "caching between
> transactions"
> >> or commit-option A (from CMP 2.1)?
> >>
> >> This is important for real world...
> >>
> >> regards,
> >>
> >> adam
> >>
> >>
> >>
> >
> >
>
>
> --
> Dipl. Inf. adam bien
>
> BEA Technical Director
> Sun Certified Java Programmer
> Sun Certified Enterprise Java Architect
> Sun Enterprise Java Trainer
>
> Mobile: 0049(0)170 280 3144
> eMail: abien_at_adam-bien.com <mailto:abien_at_adam-bien.com>
> Homepage: www.adam-bien.com <http://www.adam-bien.com>
> Weblog: http://www.adam-bien.com/roller/page/abien
> ----------
> Book author:
>
> Enterprise Architekturen
> entwickler.press 2006
> ISBN: 393504299X
>
> and Enterprise Java Frameworks,
> J2EE Patterns, J2EE HotSpots and Struts.
>
>
>
>
> --
> Wonseok Kim
> Senior Developer, TmaxSoft


-- 
 Dipl. Inf. adam bien
 
 BEA Technical Director
 Sun Certified Java Programmer
 Sun Certified Enterprise Java Architect 
 Sun Enterprise Java Trainer
 
 Mobile: 0049(0)170 280 3144
 eMail:  abien_at_adam-bien.com
 Homepage: www.adam-bien.com
 Weblog: http://www.adam-bien.com/roller/page/abien 
 ----------
Book author:
   
   Enterprise Architekturen
   entwickler.press 2006
   ISBN: 393504299X
 
 and Enterprise Java Frameworks, 
 J2EE Patterns, J2EE HotSpots and Struts.