Entity manager with permanent buffering

EE application with JPA as a persistence layer. CMT Transactions.
I want that enitityManager will permanent buffer some long list of objects in the memory. All db writes will be done but instead of db read, the entityManager will read the objects right from the memory (by id). Every committed db transaction should also update the object on the list.
So if
entityManager.persist(anObject)
entityManager.commit();
then entityManager should put anObject to that list keeped in the memory.
I was thinking about DAO class with static lists with objects, which would layer JPA.
- (+) this would keep common list of object which would be accessible for various beans the sime time,
- (-) have no idea how to grab in that DAO class, that the transaction was committed with success and that the object on the list should be updated.
- (-) problems in the future for distributed persistence layer.
Anybody know if this is doable and won't break some jee spec?
Maybe something like that exists already?
Edited by: jpf on Apr 25, 2008 4:01 AM

Similar Messages

Database Entity Manager Concept

Hello Forte-Users,
currently I work with the Concept of the White-Paper:
Forte Database Integration Patterns
Forte Consulting
May 1996
to integrate Database-Access into my Warehouse-Application.
Because the hole Application is delivered step by step and we are new
in using Forte, I use for the first step only the patterns described for
the DBEntityMgr to get a "feeling".
The problem is, that if I use the DBEntityMgr-Concept and have many
BaseClasses to access I have a lot of interface-calls like
GetCustomer,GetProducts,etc..
The Database Session Router will also not solve this "problem" in future,
because the
ApplicationEntityMgr has than the same problem.
Question: Know anyone a way, based on the upon described facilities to use
this strategy with a solution to make more "EntityMgrSO's" to get a smaller
DBEntityMgr-Interface?
The Database Session Router is planed for using when the Application should
be used from more Users and when running the SO's on a WorkGroup-Server.
Question: Know anyone a way there to split the ApplicationEntityMgr?
Every reply is welcome.
Thanks forward to all
Joseph Mirwald
Bachmeier & Sporrer
GERMANY
EMAIL: [email protected]
Don't worry, which bug you wanna have today?

...snip
>> The bad part is that now, the "client" of the entity manager
must know
>> which entity manger to call for any particular set of
data. This negates
>> a significant part of the advantage of using the single
interface into the
>> persistence layer.
snip ...
[KUBASADA Manjunatha] We can avoid this problem by having the
EntityMgrSO method determine which entity manager to use. The client can
pass a parameter indicating which object to get. The client call would
look like,
myobject = EntityMgrSO.GetEntity(myobjectindicator);
OR
EnitytMgrSO.GetEntity(output myobj : object);
In the second case, the GetEntity method uses the run time type
of myobj to determine which entity manager to call. In both cases the
EntityMgrSO returns an object of type Object; the client would have to
cast it to the appropriate type.
Don, are there any downsides to this approach ?
Manjunatha Kubasada
Complete Business Solutions Inc.
email : [email protected]
Ph : (248) 488-2088 X 3480
-----Original Message-----
From: Don Nelson [SMTP:[email protected]]
Sent: Saturday, November 29, 1997 4:05 PM
To: Joseph Mirwald
Cc: forte-users
Subject: Re: Database Entity Manager Concept
Joeseph,
The concept of the entity manager having less interfaces is both good
and
bad. The good part is mostly related to development - splitting up
the
calls to the various SQL managers among several entity managers allows
more
flexibility in terms of which classes have to be checked out of the
repository to add to or update the interfaces.
>> The bad part is that now, the "client" of the entity manager
must know
>> which entity manger to call for any particular set of
data. This negates
>> a significant part of the advantage of using the single
interface into the
>> persistence layer.
I've used both strategies in the past, and I tend to stay with one
entity
manager with a large number of interfaces. It moves the
responsibility of
knowing where to get the data from the client to the service, where it
usually belongs. The only real time penalty is when you compile the
partition - there will be more to compile. But since they are just
interafaces, it shouldn't be that big of a deal.
Don
At 10:49 AM 11/28/97 -0500, Joseph Mirwald wrote:
Hello Forte-Users,
currently I work with the Concept of the White-Paper:
Forte Database Integration Patterns
Forte Consulting
May 1996
to integrate Database-Access into my Warehouse-Application.
Because the hole Application is delivered step by step and we are new
in using Forte, I use for the first step only the patterns describedfor
the DBEntityMgr to get a "feeling".
The problem is, that if I use the DBEntityMgr-Concept and have many
BaseClasses to access I have a lot of interface-calls like
GetCustomer,GetProducts,etc..
The Database Session Router will also not solve this "problem" infuture,
because the
ApplicationEntityMgr has than the same problem.
Question: Know anyone a way, based on the upon described facilitiesto use
this strategy with a solution to make more "EntityMgrSO's" to get asmaller
DBEntityMgr-Interface?
The Database Session Router is planed for using when the Applicationshould
be used from more Users and when running the SO's on aWorkGroup-Server.
Question: Know anyone a way there to split the ApplicationEntityMgr?
Every reply is welcome.
Thanks forward to all
Joseph Mirwald
Bachmeier & Sporrer
GERMANY
EMAIL: [email protected]
Don't worry, which bug you wanna have today?
============================================
Don Nelson
Regional Consulting Manager - Rocky Mountain Region
Forte Software, Inc.
Denver, CO
Corporate voice mail: 510-986-3810
aka: [email protected]
============================================
"The good thing about drawing a tiger is that it automatically makes
your
picture fine art." - Hobbes

Problem with non-container managed entity manager

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Is it always the same entity that is reported as 'unknown' ? You mention that it works sometimes but is it the same deployment and the same code that works? The first thing I would verify is that the ear is being created as expected by netbeans. Check the persistence.xml file and verify that all of the classes are listed that will be used as entities.
--Gordon

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Dear sirs,
I have created the EJB project module and WEB Module. Now i have to map the CMP fields of the entity bean to the underlying table. Is it possible to map the cmp fields of the entity bean with out java dictionary? If yes how can we do that.
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Hi,
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Also here is another link that specifies the databases supported by J2EE Engine.
http://help.sap.com/saphelp_nw04s/helpdata/en/66/a5283eeb47b40be10000000a114084/frameset.htm
The below link shows how to specify the database vendor and datasource
http://help.sap.com/saphelp_nw04s/helpdata/en/e1/67fc3ee241ba28e10000000a114084/frameset.htm
Hope you are able to solve the problem.
Do let us know if you come up with the solution.
Regards,
Harish
Message was edited by: HARISH SUBRAMANIAN

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Entity manager Slow down

Hey all Well I was just wonder if you guys could give me some insight? I am using the entity manager and It seems like I can do a transaction.. But as I keep doing the transaction to add elements.. It runs fine but then all of a sudden it just hangs? here my code? any insight would be greatly appreciated.. even if its just a theory
selectedCustomer.getLevelIdSellCollection().add(item);
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                               Message was edited by:
jbayuga
Message was edited by:
jbayuga

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If you have created either a Roll, or Crawl, with the Animation Preset, then you will want to increase the Duration of that Title, to slow it down. You can do this by click+dragging on the Tail of the Title.
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Recommended way of getting entity manager from pojo class

Hi,
In our application we have the need or retrieving entity manager from 'pojo' classes.
More specifically we have singleton classes which act as 'data' repositories and are accessed from both servlets and ejb.
I'm aware that the repositories classes might be problematic, but in the current stage we can't perform significant change in application structure so I am looking for a 'fast' solution as possible.
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To obtain an EntityManager instance, first must obtain an EntityManagerFactory instance by injecting it into the application component by means of the javax.persistence.PersistenceUnit annotation:
@PersistenceUnit
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Then, obtain an EntityManager from the EntityManagerFactory instance:
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http://download.oracle.com/javaee/5/tutorial/doc/bnbqw.html
Edited by: dvohra16 on Apr 14, 2011 5:06 PM

JPA and Entity manager.

Hi all,
I have a "simple" question:
Should I create a class to manage entity manager and entity manager factory on JPA2?
Why do I ask that? Because I read on J2EE tutorial:
With a container-managed entity manager, an EntityManager instance’s persistence context is automatically propagated by the container to all application components that use the EntityManager instance within a single Java Transaction Architecture (JTA) transaction.
To obtain an EntityManager instance, inject the entity manager into the application component:
@PersistenceContext
EntityManager em;
I'm using JSF2, JPA2, JTA and Glassfish3.1 on the NetBeans 7.0.1.
The wizard that creates the JSF's pages from entity class does a good work but I have some problem in the other classes.
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Filippo Tenaglia wrote:
Hi all,
I have a "simple" question:
Should I create a class to manage entity manager and entity manager factory on JPA2?That question is far from complete, as the answer to this one is "depends on what you want to do!"
Why do I ask that? Because I read on J2EE tutorial:
With a container-managed entity manager, an EntityManager instance’s persistence context is automatically propagated by the container to all application components that use the EntityManager instance within a single Java Transaction Architecture (JTA) transaction.
To obtain an EntityManager instance, inject the entity manager into the application component:
@PersistenceContext
EntityManager em;
Given this information...
I'm using JSF2, JPA2, JTA and Glassfish3.1 on the NetBeans 7.0.1.That answer to your question is "NO", because you have a container available to you that can do the work (Glassfish). It makes no sense using Glassfish and then purposely ignoring the features it has to offer.
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Error While Deploying A CMP Entity Bean With A Composite Primary Key

Hello all,
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PrimaryKey feature.
Regards,
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Sorry John, I didn't see your post when I clicked the reply button. Dennis

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I have two app servers and two clones each clone is running in each app server.
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