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Posted to dev@myfaces.apache.org by Jakob Korherr <ja...@gmail.com> on 2010/01/13 12:42:15 UTC
[core] Introduce ManagedBeanRegistry
Hi guys,
To ensure the execution of the ManagedBean's @PreDestroy methods on a
container shutdown/restart, I would like to introduce a ManagedBeanRegistry,
in which all active ManagedBeans from all scopes are referenced.
The problem is the following: At the moment on a container shutdown or
restart, only contextDestroyed is invoked (tested in tomcat 6), thus only
the @PreDestroy methods of all ApplicationScoped ManagedBeans will be
invoked, but not those of any existing ManagedBeans in session, request,
view (and maybe also custom) scope, because they can not be referenced in
contextDestroyed().
Any opinions on that?
Thanks in advance!
Regards,
Jakob
Re: [core] Introduce ManagedBeanRegistry
Posted by Mark Struberg <st...@yahoo.de>.
Session handling is a pretty complex topic.
I assume that a HttpSessionListener#sessionDestroyed() is only be called if
a) a session times out
b) the server shuts down and no session persistence is available
would that be an option?
LieGrue,
strub
--- On Thu, 1/14/10, Jakob Korherr <ja...@gmail.com> wrote:
> From: Jakob Korherr <ja...@gmail.com>
> Subject: Re: [core] Introduce ManagedBeanRegistry
> To: "MyFaces Development" <de...@myfaces.apache.org>
> Date: Thursday, January 14, 2010, 2:20 PM
> Hi,
>
> I just answered to your comment in the JIRA:
>
> So you're saying it would be better not to destroy all
> session beans on
> a container shutdown, because they are maybe serialized?
> Then what
> about a config parameter to turn this feature on or off?
>
>
>
>
>
> And what about view and request beans?
>
> Regards,
> Jakob
>
> 2010/1/14 Bernhard Huemer <be...@gmail.com>
>
> Hey,
>
>
>
> sorry, I haven't noticed this thread, so I've
> already commented on the according JIRA issue (https://issues.apache.org/jira/browse/MYFACES-2485).
> Basically I've already mentioned it there, but I think
> the reason why only the
> "contextDestroyed"-callbacks are invoked is that
> Tomcat, by default, serializes and preserves sessions once
> it shuts down.
>
>
>
>
> However, I'm pretty much sure that implementing such a
> registry introduces more issues than it resolves (assuming
> that you consider this to be an issue at all - which I
> wouldn't do). As Jan-Kees has already pointed out, you
> can't just invalidate sessions once a container shuts
> down in a clustered environment. I think it would break the
> whole idea of a clustered environment.
>
>
>
>
> regards,
>
> Bernhard
>
>
>
> Jakob Korherr wrote on 01/13/2010 09:17 PM (GMT):
>
>
> Hi,
>
>
>
> MyFaces is already using all available Listeners
> (HttpSessionAttributeListener, HttpSessionListener,
> ServletContextListener, ServletContextAttributeListener,
> ServletRequestListener, ServletRequestAttributeListener) to
> invoke @PreDestroy on the Managed Beans and this happens via
> a pass-through from StartupServletContextListener, so you
> don't have to configure two listeners in web.xml (or
> tld).
>
>
>
>
> The problem is, as you thought, that those listeners (e.g.
> HttpSessionListener) are not invoked on a container
> shutdown/restart. Only contextDestroyed from
> ServletContextListener is invoked (tested today on Apache
> Tomcat 6).
>
>
>
>
> I will not change anything of the existing behavior, I just
> want to make sure that all still existing ManagedBeans get
> their @PreDestroy method called in contextDestroyed. But I
> would not get a reference to them, if I do not register them
> in a ManagedBeanRegistry.
>
>
>
>
> Regards,
>
> Jakob
>
>
>
> 2010/1/13 Jan-Kees van Andel <jankeesvanandel@gmail.com
> <ma...@gmail.com>>
>
>
>
>
> Hey,
>
>
>
> How about an HttpSessionListener? I'm not sure
> if
>
> HttpSessionListener.contextDestroyed is invoked on
> shutdownthough.
>
> Probably not...
>
>
>
> I'm afraid the only option is custom bookkeeping,
> maybe using an
>
> HttpSessionListener/ServletContextListener to publish
> events to the
>
> Registry.
>
> I see some issues with this approach:
>
> 1 Configuration becomes more difficult for the
> application developer,
>
> because these two Listeners become required
> configuration.
>
> 2 Managing objects yourself may be tricky business.
> An option could be
>
> to use WeakReference/WeakHashMap for this so you
> don't accidentally
>
> keep your objects alive.
>
> 3 What to do with regards to session replication on a
> clustered
>
> environment? I'm not sure this will become an
> issue, but it wouldn't
>
> surprise me if it will.
>
>
>
> Regards,
>
> Jan-Kees
>
>
>
>
>
> 2010/1/13 Jakob Korherr <jakob.korherr@gmail.com
>
> <ma...@gmail.com>>:
>
> > Hi guys,
>
> >
>
> > To ensure the execution of the
> ManagedBean's @PreDestroy methods on a
>
> > container shutdown/restart, I would like to
> introduce a
>
> ManagedBeanRegistry,
>
> > in which all active ManagedBeans from all
> scopes are referenced.
>
> >
>
> > The problem is the following: At the moment on
> a container
>
> shutdown or
>
> > restart, only contextDestroyed is invoked
> (tested in tomcat 6),
>
> thus only
>
> > the @PreDestroy methods of all
> ApplicationScoped ManagedBeans will be
>
> > invoked, but not those of any existing
> ManagedBeans in session,
>
> request,
>
> > view (and maybe also custom) scope, because
> they can not be
>
> referenced in
>
> > contextDestroyed().
>
> >
>
> > Any opinions on that?
>
> >
>
> > Thanks in advance!
>
> >
>
> > Regards,
>
> > Jakob
>
> >
>
>
>
>
>
>
>
>
>
>
>
Re: [core] Introduce ManagedBeanRegistry
Posted by Jakob Korherr <ja...@gmail.com>.
Hi,
I just answered to your comment in the JIRA:
So you're saying it would be better not to destroy all session beans on a
container shutdown, because they are maybe serialized? Then what about a
config parameter to turn this feature on or off?
And what about view and request beans?
Regards,
Jakob
2010/1/14 Bernhard Huemer <be...@gmail.com>
> Hey,
>
> sorry, I haven't noticed this thread, so I've already commented on the
> according JIRA issue (https://issues.apache.org/jira/browse/MYFACES-2485).
> Basically I've already mentioned it there, but I think the reason why only
> the "contextDestroyed"-callbacks are invoked is that Tomcat, by default,
> serializes and preserves sessions once it shuts down.
>
> However, I'm pretty much sure that implementing such a registry introduces
> more issues than it resolves (assuming that you consider this to be an issue
> at all - which I wouldn't do). As Jan-Kees has already pointed out, you
> can't just invalidate sessions once a container shuts down in a clustered
> environment. I think it would break the whole idea of a clustered
> environment.
>
> regards,
> Bernhard
>
> Jakob Korherr wrote on 01/13/2010 09:17 PM (GMT):
>
>> Hi,
>>
>> MyFaces is already using all available Listeners
>> (HttpSessionAttributeListener, HttpSessionListener, ServletContextListener,
>> ServletContextAttributeListener, ServletRequestListener,
>> ServletRequestAttributeListener) to invoke @PreDestroy on the Managed Beans
>> and this happens via a pass-through from StartupServletContextListener, so
>> you don't have to configure two listeners in web.xml (or tld).
>>
>> The problem is, as you thought, that those listeners (e.g.
>> HttpSessionListener) are not invoked on a container shutdown/restart. Only
>> contextDestroyed from ServletContextListener is invoked (tested today on
>> Apache Tomcat 6).
>>
>> I will not change anything of the existing behavior, I just want to make
>> sure that all still existing ManagedBeans get their @PreDestroy method
>> called in contextDestroyed. But I would not get a reference to them, if I do
>> not register them in a ManagedBeanRegistry.
>>
>> Regards,
>> Jakob
>>
>> 2010/1/13 Jan-Kees van Andel <jankeesvanandel@gmail.com <mailto:
>> jankeesvanandel@gmail.com>>
>>
>>
>> Hey,
>>
>> How about an HttpSessionListener? I'm not sure if
>> HttpSessionListener.contextDestroyed is invoked on shutdownthough.
>> Probably not...
>>
>> I'm afraid the only option is custom bookkeeping, maybe using an
>> HttpSessionListener/ServletContextListener to publish events to the
>> Registry.
>> I see some issues with this approach:
>> 1 Configuration becomes more difficult for the application developer,
>> because these two Listeners become required configuration.
>> 2 Managing objects yourself may be tricky business. An option could be
>> to use WeakReference/WeakHashMap for this so you don't accidentally
>> keep your objects alive.
>> 3 What to do with regards to session replication on a clustered
>> environment? I'm not sure this will become an issue, but it wouldn't
>> surprise me if it will.
>>
>> Regards,
>> Jan-Kees
>>
>>
>> 2010/1/13 Jakob Korherr <jakob.korherr@gmail.com
>> <ma...@gmail.com>>:
>>
>> > Hi guys,
>> >
>> > To ensure the execution of the ManagedBean's @PreDestroy methods on
>> a
>> > container shutdown/restart, I would like to introduce a
>> ManagedBeanRegistry,
>> > in which all active ManagedBeans from all scopes are referenced.
>> >
>> > The problem is the following: At the moment on a container
>> shutdown or
>> > restart, only contextDestroyed is invoked (tested in tomcat 6),
>> thus only
>> > the @PreDestroy methods of all ApplicationScoped ManagedBeans will
>> be
>> > invoked, but not those of any existing ManagedBeans in session,
>> request,
>> > view (and maybe also custom) scope, because they can not be
>> referenced in
>> > contextDestroyed().
>> >
>> > Any opinions on that?
>> >
>> > Thanks in advance!
>> >
>> > Regards,
>> > Jakob
>> >
>>
>>
>>
>
Re: [core] Introduce ManagedBeanRegistry
Posted by Bernhard Huemer <be...@gmail.com>.
Hey,
sorry, I haven't noticed this thread, so I've already commented on the
according JIRA issue
(https://issues.apache.org/jira/browse/MYFACES-2485). Basically I've
already mentioned it there, but I think the reason why only the
"contextDestroyed"-callbacks are invoked is that Tomcat, by default,
serializes and preserves sessions once it shuts down.
However, I'm pretty much sure that implementing such a registry
introduces more issues than it resolves (assuming that you consider this
to be an issue at all - which I wouldn't do). As Jan-Kees has already
pointed out, you can't just invalidate sessions once a container shuts
down in a clustered environment. I think it would break the whole idea
of a clustered environment.
regards,
Bernhard
Jakob Korherr wrote on 01/13/2010 09:17 PM (GMT):
> Hi,
>
> MyFaces is already using all available Listeners
> (HttpSessionAttributeListener, HttpSessionListener,
> ServletContextListener, ServletContextAttributeListener,
> ServletRequestListener, ServletRequestAttributeListener) to invoke
> @PreDestroy on the Managed Beans and this happens via a pass-through
> from StartupServletContextListener, so you don't have to configure two
> listeners in web.xml (or tld).
>
> The problem is, as you thought, that those listeners (e.g.
> HttpSessionListener) are not invoked on a container shutdown/restart.
> Only contextDestroyed from ServletContextListener is invoked (tested
> today on Apache Tomcat 6).
>
> I will not change anything of the existing behavior, I just want to make
> sure that all still existing ManagedBeans get their @PreDestroy method
> called in contextDestroyed. But I would not get a reference to them, if
> I do not register them in a ManagedBeanRegistry.
>
> Regards,
> Jakob
>
> 2010/1/13 Jan-Kees van Andel <jankeesvanandel@gmail.com
> <ma...@gmail.com>>
>
> Hey,
>
> How about an HttpSessionListener? I'm not sure if
> HttpSessionListener.contextDestroyed is invoked on shutdownthough.
> Probably not...
>
> I'm afraid the only option is custom bookkeeping, maybe using an
> HttpSessionListener/ServletContextListener to publish events to the
> Registry.
> I see some issues with this approach:
> 1 Configuration becomes more difficult for the application developer,
> because these two Listeners become required configuration.
> 2 Managing objects yourself may be tricky business. An option could be
> to use WeakReference/WeakHashMap for this so you don't accidentally
> keep your objects alive.
> 3 What to do with regards to session replication on a clustered
> environment? I'm not sure this will become an issue, but it wouldn't
> surprise me if it will.
>
> Regards,
> Jan-Kees
>
>
> 2010/1/13 Jakob Korherr <jakob.korherr@gmail.com
> <ma...@gmail.com>>:
> > Hi guys,
> >
> > To ensure the execution of the ManagedBean's @PreDestroy methods on a
> > container shutdown/restart, I would like to introduce a
> ManagedBeanRegistry,
> > in which all active ManagedBeans from all scopes are referenced.
> >
> > The problem is the following: At the moment on a container
> shutdown or
> > restart, only contextDestroyed is invoked (tested in tomcat 6),
> thus only
> > the @PreDestroy methods of all ApplicationScoped ManagedBeans will be
> > invoked, but not those of any existing ManagedBeans in session,
> request,
> > view (and maybe also custom) scope, because they can not be
> referenced in
> > contextDestroyed().
> >
> > Any opinions on that?
> >
> > Thanks in advance!
> >
> > Regards,
> > Jakob
> >
>
>
Re: [core] Introduce ManagedBeanRegistry
Posted by Jakob Korherr <ja...@gmail.com>.
Hi,
MyFaces is already using all available Listeners
(HttpSessionAttributeListener, HttpSessionListener, ServletContextListener,
ServletContextAttributeListener, ServletRequestListener,
ServletRequestAttributeListener) to invoke @PreDestroy on the Managed Beans
and this happens via a pass-through from StartupServletContextListener, so
you don't have to configure two listeners in web.xml (or tld).
The problem is, as you thought, that those listeners (e.g.
HttpSessionListener) are not invoked on a container shutdown/restart. Only
contextDestroyed from ServletContextListener is invoked (tested today on
Apache Tomcat 6).
I will not change anything of the existing behavior, I just want to make
sure that all still existing ManagedBeans get their @PreDestroy method
called in contextDestroyed. But I would not get a reference to them, if I do
not register them in a ManagedBeanRegistry.
Regards,
Jakob
2010/1/13 Jan-Kees van Andel <ja...@gmail.com>
> Hey,
>
> How about an HttpSessionListener? I'm not sure if
> HttpSessionListener.contextDestroyed is invoked on shutdownthough.
> Probably not...
>
> I'm afraid the only option is custom bookkeeping, maybe using an
> HttpSessionListener/ServletContextListener to publish events to the
> Registry.
> I see some issues with this approach:
> 1 Configuration becomes more difficult for the application developer,
> because these two Listeners become required configuration.
> 2 Managing objects yourself may be tricky business. An option could be
> to use WeakReference/WeakHashMap for this so you don't accidentally
> keep your objects alive.
> 3 What to do with regards to session replication on a clustered
> environment? I'm not sure this will become an issue, but it wouldn't
> surprise me if it will.
>
> Regards,
> Jan-Kees
>
>
> 2010/1/13 Jakob Korherr <ja...@gmail.com>:
> > Hi guys,
> >
> > To ensure the execution of the ManagedBean's @PreDestroy methods on a
> > container shutdown/restart, I would like to introduce a
> ManagedBeanRegistry,
> > in which all active ManagedBeans from all scopes are referenced.
> >
> > The problem is the following: At the moment on a container shutdown or
> > restart, only contextDestroyed is invoked (tested in tomcat 6), thus only
> > the @PreDestroy methods of all ApplicationScoped ManagedBeans will be
> > invoked, but not those of any existing ManagedBeans in session, request,
> > view (and maybe also custom) scope, because they can not be referenced in
> > contextDestroyed().
> >
> > Any opinions on that?
> >
> > Thanks in advance!
> >
> > Regards,
> > Jakob
> >
>
Re: [core] Introduce ManagedBeanRegistry
Posted by Jan-Kees van Andel <ja...@gmail.com>.
Hey,
How about an HttpSessionListener? I'm not sure if
HttpSessionListener.contextDestroyed is invoked on shutdownthough.
Probably not...
I'm afraid the only option is custom bookkeeping, maybe using an
HttpSessionListener/ServletContextListener to publish events to the
Registry.
I see some issues with this approach:
1 Configuration becomes more difficult for the application developer,
because these two Listeners become required configuration.
2 Managing objects yourself may be tricky business. An option could be
to use WeakReference/WeakHashMap for this so you don't accidentally
keep your objects alive.
3 What to do with regards to session replication on a clustered
environment? I'm not sure this will become an issue, but it wouldn't
surprise me if it will.
Regards,
Jan-Kees
2010/1/13 Jakob Korherr <ja...@gmail.com>:
> Hi guys,
>
> To ensure the execution of the ManagedBean's @PreDestroy methods on a
> container shutdown/restart, I would like to introduce a ManagedBeanRegistry,
> in which all active ManagedBeans from all scopes are referenced.
>
> The problem is the following: At the moment on a container shutdown or
> restart, only contextDestroyed is invoked (tested in tomcat 6), thus only
> the @PreDestroy methods of all ApplicationScoped ManagedBeans will be
> invoked, but not those of any existing ManagedBeans in session, request,
> view (and maybe also custom) scope, because they can not be referenced in
> contextDestroyed().
>
> Any opinions on that?
>
> Thanks in advance!
>
> Regards,
> Jakob
>