Re: LDM - correct construction
Hi Jeffrey,
Have a look to the Command Pattern.
https://community.jboss.org/wiki/OpenSessionInView
http://heapdump.wordpress.com/2010/04/04/should-i-use-open-session-in-view/
quote from Hibernate:
It's clear that this pattern only makes sense if you can actually use a local
Session when rendering the view.
In a three-tier environment the view might be rendered on the presentation
virtual machine, not on the service virtual machine with the business and data
access layer. Therefore, keeping the Session and transaction open is not an
option. In this case you have to send the right "amount" of data to the
presentation layer, so a view can be constructed with the Session already
closed. It depends on your architecture if you better use Detached Objects,
Data Transfer Objects, or maybe a mix of both with the Command Pattern.
This pattern should be more widespread.
Compare to the OSIV, it's much better ! :-)
Long live to the Command Pattern !
François
Le 21 mars 2012 à 22:49, Jeffrey Schneller a écrit :
> The application is using the open-session-in-view pattern which is what makes
> this so troubling to figure out.
>
>
>
> -Original Message-
> From: Dan Retzlaff [mailto:dretzl...@gmail.com]
> Sent: Wednesday, March 21, 2012 5:44 PM
> To: users@wicket.apache.org
> Subject: Re: LDM - correct construction
>
> That sounds like a good strategy. Generally speaking, applications use an
> open-session-in-view pattern which makes it easy to ensure that the Hibernate
> session gets closed. As long as that happens, the (mis)handling of
> transactions shouldn't cause your symptoms.
>
> On Wed, Mar 21, 2012 at 2:31 PM, Jeffrey Schneller <
> jeffrey.schnel...@envisa.com> wrote:
>
>> My service implementation uses hibernate dao objects which should be
>> managing its own connections via the c3p0 connection pool. All my
>> service objects and Dao objects are marked as singletons in my Spring
>> applicationContext.xml file. I don't think any of my transactions are
>> failing as it would most likely throw an exception if the there was a
>> problem performing a transactions and all exceptions are logged (at
>> least I believe they are).
>>
>> I will most likely put the following c3p0 settings in place and wait
>> to see what comes out of this in production.
>>
>> c3p0.unreturnedConnectionTimeout=30
>> c3p0.debugUnreturnedConnectionStackTraces=true
>>
>> This should give me a stack trace of what checked out a connection,
>> where that connection hasn't been returned to the pool in 30 seconds.
>> It will be a slight performance hit on production but I should be able
>> to find the problem very quickly.
>>
>> Thanks.
>>
>> Jeff
>>
>> -Original Message-
>> From: Dan Retzlaff [mailto:dretzl...@gmail.com]
>> Sent: Wednesday, March 21, 2012 5:04 PM
>> To: users@wicket.apache.org
>> Subject: Re: LDM - correct construction
>>
>> Jeffrey,
>>
>> That won't prevent a connection from being released. The LDM holds a
>> reference to the page, and the page has a serializable proxy to the
>> service implementation. No problem there. Injecting the service into
>> the LDM is only an advantage if you want to share it among pages; then
>> the LDM can be static and its page reference goes away.
>>
>> It sounds like your service implementation may have an issue. Does
>> your service manage its own connections? If so, is it a singleton?
>> Other than that, I'd guess there's a bug in your transaction
>> management such that a transaction gets started but not finished.
>>
>> HTH,
>> Dan
>>
>> On Wed, Mar 21, 2012 at 1:45 PM, Jeffrey Schneller <
>> jeffrey.schnel...@envisa.com> wrote:
>>
>>> Is this the correct construction of a LDM where I need to use a
>>> service bean to access my database? The IMyService bean is
>>> injected on the page and passed to the LDM. Does this make the LDM
>>> hold a reference to the IMyService bean and possibly keep a
>>> connection from being put back into the
>>> c3p0 db connection pool? After some period of time my application
>>> is blocked with all threads waiting on a connection to the db.
>>>
>>> Should I be injected the IMyService bean into the LDM using the
>>> commented out code. Thanks for any help.
>>>
>>> public class MyLDM extends
>>> LoadableDetachableModel {
>>>
>>> //@SpringBean
>>> private IMyService service;
>>>
>>>
RE: LDM - correct construction
The application is using the open-session-in-view pattern which is what makes
this so troubling to figure out.
-Original Message-
From: Dan Retzlaff [mailto:dretzl...@gmail.com]
Sent: Wednesday, March 21, 2012 5:44 PM
To: users@wicket.apache.org
Subject: Re: LDM - correct construction
That sounds like a good strategy. Generally speaking, applications use an
open-session-in-view pattern which makes it easy to ensure that the Hibernate
session gets closed. As long as that happens, the (mis)handling of transactions
shouldn't cause your symptoms.
On Wed, Mar 21, 2012 at 2:31 PM, Jeffrey Schneller <
jeffrey.schnel...@envisa.com> wrote:
> My service implementation uses hibernate dao objects which should be
> managing its own connections via the c3p0 connection pool. All my
> service objects and Dao objects are marked as singletons in my Spring
> applicationContext.xml file. I don't think any of my transactions are
> failing as it would most likely throw an exception if the there was a
> problem performing a transactions and all exceptions are logged (at
> least I believe they are).
>
> I will most likely put the following c3p0 settings in place and wait
> to see what comes out of this in production.
>
> c3p0.unreturnedConnectionTimeout=30
> c3p0.debugUnreturnedConnectionStackTraces=true
>
> This should give me a stack trace of what checked out a connection,
> where that connection hasn't been returned to the pool in 30 seconds.
> It will be a slight performance hit on production but I should be able
> to find the problem very quickly.
>
> Thanks.
>
> Jeff
>
> -Original Message-
> From: Dan Retzlaff [mailto:dretzl...@gmail.com]
> Sent: Wednesday, March 21, 2012 5:04 PM
> To: users@wicket.apache.org
> Subject: Re: LDM - correct construction
>
> Jeffrey,
>
> That won't prevent a connection from being released. The LDM holds a
> reference to the page, and the page has a serializable proxy to the
> service implementation. No problem there. Injecting the service into
> the LDM is only an advantage if you want to share it among pages; then
> the LDM can be static and its page reference goes away.
>
> It sounds like your service implementation may have an issue. Does
> your service manage its own connections? If so, is it a singleton?
> Other than that, I'd guess there's a bug in your transaction
> management such that a transaction gets started but not finished.
>
> HTH,
> Dan
>
> On Wed, Mar 21, 2012 at 1:45 PM, Jeffrey Schneller <
> jeffrey.schnel...@envisa.com> wrote:
>
> > Is this the correct construction of a LDM where I need to use a
> > service bean to access my database? The IMyService bean is
> > injected on the page and passed to the LDM. Does this make the LDM
> > hold a reference to the IMyService bean and possibly keep a
> > connection from being put back into the
> > c3p0 db connection pool? After some period of time my application
> > is blocked with all threads waiting on a connection to the db.
> >
> > Should I be injected the IMyService bean into the LDM using the
> > commented out code. Thanks for any help.
> >
> > public class MyLDM extends
> > LoadableDetachableModel {
> >
> >//@SpringBean
> >private IMyService service;
> >
> >private String id;
> >
> >public MyLDM(String id, IMyService service) {
> >this.id = id;
> >this.service = service;
> >}
> >
> >
> >//public MyLDM(String id) {
> >//this.id = id;
> >//}
> >
> >
> >@Override
> >protected com.example.MyObject load() {
> > //InjectorHolder.getInjector().inject(this);
> >return service.getMyObject(this.id);
> >}
> > }
> >
>
> -
> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
> For additional commands, e-mail: users-h...@wicket.apache.org
>
>
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Re: LDM - correct construction
That sounds like a good strategy. Generally speaking, applications use an
open-session-in-view pattern which makes it easy to ensure that the
Hibernate session gets closed. As long as that happens, the (mis)handling
of transactions shouldn't cause your symptoms.
On Wed, Mar 21, 2012 at 2:31 PM, Jeffrey Schneller <
jeffrey.schnel...@envisa.com> wrote:
> My service implementation uses hibernate dao objects which should be
> managing its own connections via the c3p0 connection pool. All my service
> objects and Dao objects are marked as singletons in my Spring
> applicationContext.xml file. I don't think any of my transactions are
> failing as it would most likely throw an exception if the there was a
> problem performing a transactions and all exceptions are logged (at least I
> believe they are).
>
> I will most likely put the following c3p0 settings in place and wait to
> see what comes out of this in production.
>
> c3p0.unreturnedConnectionTimeout=30
> c3p0.debugUnreturnedConnectionStackTraces=true
>
> This should give me a stack trace of what checked out a connection, where
> that connection hasn't been returned to the pool in 30 seconds. It will be
> a slight performance hit on production but I should be able to find the
> problem very quickly.
>
> Thanks.
>
> Jeff
>
> -Original Message-
> From: Dan Retzlaff [mailto:dretzl...@gmail.com]
> Sent: Wednesday, March 21, 2012 5:04 PM
> To: users@wicket.apache.org
> Subject: Re: LDM - correct construction
>
> Jeffrey,
>
> That won't prevent a connection from being released. The LDM holds a
> reference to the page, and the page has a serializable proxy to the service
> implementation. No problem there. Injecting the service into the LDM is
> only an advantage if you want to share it among pages; then the LDM can be
> static and its page reference goes away.
>
> It sounds like your service implementation may have an issue. Does your
> service manage its own connections? If so, is it a singleton? Other than
> that, I'd guess there's a bug in your transaction management such that a
> transaction gets started but not finished.
>
> HTH,
> Dan
>
> On Wed, Mar 21, 2012 at 1:45 PM, Jeffrey Schneller <
> jeffrey.schnel...@envisa.com> wrote:
>
> > Is this the correct construction of a LDM where I need to use a
> > service bean to access my database? The IMyService bean is injected
> > on the page and passed to the LDM. Does this make the LDM hold a
> > reference to the IMyService bean and possibly keep a connection from
> > being put back into the
> > c3p0 db connection pool? After some period of time my application is
> > blocked with all threads waiting on a connection to the db.
> >
> > Should I be injected the IMyService bean into the LDM using the
> > commented out code. Thanks for any help.
> >
> > public class MyLDM extends
> > LoadableDetachableModel {
> >
> >//@SpringBean
> >private IMyService service;
> >
> >private String id;
> >
> >public MyLDM(String id, IMyService service) {
> >this.id = id;
> >this.service = service;
> >}
> >
> >
> >//public MyLDM(String id) {
> >//this.id = id;
> >//}
> >
> >
> >@Override
> >protected com.example.MyObject load() {
> > //InjectorHolder.getInjector().inject(this);
> >return service.getMyObject(this.id);
> >}
> > }
> >
>
> -
> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
> For additional commands, e-mail: users-h...@wicket.apache.org
>
>
RE: LDM - correct construction
My service implementation uses hibernate dao objects which should be managing
its own connections via the c3p0 connection pool. All my service objects and
Dao objects are marked as singletons in my Spring applicationContext.xml file.
I don't think any of my transactions are failing as it would most likely throw
an exception if the there was a problem performing a transactions and all
exceptions are logged (at least I believe they are).
I will most likely put the following c3p0 settings in place and wait to see
what comes out of this in production.
c3p0.unreturnedConnectionTimeout=30
c3p0.debugUnreturnedConnectionStackTraces=true
This should give me a stack trace of what checked out a connection, where that
connection hasn't been returned to the pool in 30 seconds. It will be a slight
performance hit on production but I should be able to find the problem very
quickly.
Thanks.
Jeff
-Original Message-
From: Dan Retzlaff [mailto:dretzl...@gmail.com]
Sent: Wednesday, March 21, 2012 5:04 PM
To: users@wicket.apache.org
Subject: Re: LDM - correct construction
Jeffrey,
That won't prevent a connection from being released. The LDM holds a reference
to the page, and the page has a serializable proxy to the service
implementation. No problem there. Injecting the service into the LDM is only an
advantage if you want to share it among pages; then the LDM can be static and
its page reference goes away.
It sounds like your service implementation may have an issue. Does your service
manage its own connections? If so, is it a singleton? Other than that, I'd
guess there's a bug in your transaction management such that a transaction gets
started but not finished.
HTH,
Dan
On Wed, Mar 21, 2012 at 1:45 PM, Jeffrey Schneller <
jeffrey.schnel...@envisa.com> wrote:
> Is this the correct construction of a LDM where I need to use a
> service bean to access my database? The IMyService bean is injected
> on the page and passed to the LDM. Does this make the LDM hold a
> reference to the IMyService bean and possibly keep a connection from
> being put back into the
> c3p0 db connection pool? After some period of time my application is
> blocked with all threads waiting on a connection to the db.
>
> Should I be injected the IMyService bean into the LDM using the
> commented out code. Thanks for any help.
>
> public class MyLDM extends
> LoadableDetachableModel {
>
>//@SpringBean
>private IMyService service;
>
>private String id;
>
>public MyLDM(String id, IMyService service) {
>this.id = id;
>this.service = service;
>}
>
>
>//public MyLDM(String id) {
>//this.id = id;
>//}
>
>
>@Override
>protected com.example.MyObject load() {
> //InjectorHolder.getInjector().inject(this);
>return service.getMyObject(this.id);
>}
> }
>
-
To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
For additional commands, e-mail: users-h...@wicket.apache.org
Re: LDM - correct construction
Jeffrey,
That won't prevent a connection from being released. The LDM holds a
reference to the page, and the page has a serializable proxy to the service
implementation. No problem there. Injecting the service into the LDM is
only an advantage if you want to share it among pages; then the LDM can be
static and its page reference goes away.
It sounds like your service implementation may have an issue. Does your
service manage its own connections? If so, is it a singleton? Other than
that, I'd guess there's a bug in your transaction management such that a
transaction gets started but not finished.
HTH,
Dan
On Wed, Mar 21, 2012 at 1:45 PM, Jeffrey Schneller <
jeffrey.schnel...@envisa.com> wrote:
> Is this the correct construction of a LDM where I need to use a service
> bean to access my database? The IMyService bean is injected on the page
> and passed to the LDM. Does this make the LDM hold a reference to the
> IMyService bean and possibly keep a connection from being put back into the
> c3p0 db connection pool? After some period of time my application is
> blocked with all threads waiting on a connection to the db.
>
> Should I be injected the IMyService bean into the LDM using the commented
> out code. Thanks for any help.
>
> public class MyLDM extends LoadableDetachableModel {
>
>//@SpringBean
>private IMyService service;
>
>private String id;
>
>public MyLDM(String id, IMyService service) {
>this.id = id;
>this.service = service;
>}
>
>
>//public MyLDM(String id) {
>//this.id = id;
>//}
>
>
>@Override
>protected com.example.MyObject load() {
> //InjectorHolder.getInjector().inject(this);
>return service.getMyObject(this.id);
>}
> }
>
