URGENT - EJB 2 BMP Entities - Is it OK to use On Delete Cascade?

Hi All
i have a system that im currently working on in EJB 2 using bean managed persitence and need to implement a cascade delete funtionality when i delete a particular entity.
am i going to break the EJB spec or the system if I use the On Delete Cascade clause on my database tables so all rows are automatically removed from the DB?
Unfortuantely its an existing system to upgrading to EJB 3 isnt an option.
i know i could use multiple sql statements to delete associated entites or even use the delete methods on associated entity beans, but i feel that using on delete cascade would be far more efficient than all of the above.
i really need a quick answer on this (ive got to have the code done by wed morning) so if anyone could give me a quick pointer on which method i use id be extremely grateful.
Thanks in advance.
Gaz.
Message was edited by:
mrblue

Hello jcannon,
Designing filters is heavily signal-dependent. There is no overall best filter, most appropriate passband ripple, or stopband attenuation. For some guidelines, please see the following links:
Filter choice:
http://digital.ni.com/public.nsf/allkb/B5C159262A4976DD86256C2F005EAB94?OpenDocument
LabVIEW Elliptic Filter PtByPt VI:
http://zone.ni.com/reference/en-XX/help/371361G-01/ptbypt/elliptic_filter_ptbypt/
Filter Specifications:
https://ccrma.stanford.edu/~jos/sasp/Lowpass_Filter_Design_Specifications.html
I would suggest simply adjusting these values until your filter behaves the way you need according to your application.
Patrick W.
Applications Engineer
National Instruments

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Rob Woollen wrote:
Alexander Shvets wrote:
Hi,
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I have some key basic questions on BMP Entity Beans. I have been looking at the sample application at http://developers.sun.com/tools/javatools/documentation/s1s5/accountapp.html.
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PreparedStatement prepStmt = con.prepareStatement(selectStatement);
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2. In the same example above, in section (implementing the bean's other methods, steps 3 and 4) it says:
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id = (String) context.getPrimaryKey();
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Thanks in advance.

Greetings,
1. I have a database that is pre-populated by some external ways other than EJBs. Does my BMP
Entity Bean that i mapped to a specific table know about the previous data. In the sampleThe container will not have any beans representing the new data until the client attempts to find them.
String selectStatement = "select balance from account where id = ? ";
PreparedStatement prepStmt = con.prepareStatement(selectStatement);
prepStmt.setString(1,this.id);
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but in the ejbCreate() method. For example, if myThe ejbCreate method returns an instance of the Primary Key class which the container stores in the EJBObject. In this case, the PK class is type String and referenced by the variable 'id'.
client program just wants to list the balance from accounts table bound to an id without inserting
new rows into the database, how would that happen? ItPresumably, the client knows the "primary key" of the entity (the unique tuple from the accounts table which the EB represents), it wants to access and uses that as the argument to a findByPrimaryKey call against the home object.
confuses me since ejbCreate method is called automatically everytime i use a bean and it contains
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2. In the same example above, in section (implementing the bean's other methods, steps 3 and 4)
it says:
public void ejbActivate() {
id = (String) context.getPrimaryKey();
Refer again to the above...
What is this id variable? There is no type definition. Is this the id that was defined in AcccountEJB
(from db mapping)? If so how do i reference to it without any class names?It is indeed the private member of AccountBean (see step 7 under "Adding a create method to the bean" of section 4).
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I seem to be unable to grab the logic of EJB BMP.
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Thanks in advance.Regards,
Tony "Vee Schade" Cook

Ejb BMP never commits even with transactions

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$ORACLE_HOME/javavm/demo/examples/ejb/transactions/clientside
I changed the last line in Client.java from crollback to commit()...
I run this program twice:
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End salary = 3300.0
Beginning salary = 3000.0
End salary = 3300.0
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any help would be greatly appreciated.
thanks,
-rick

I don't think my probmem is related to an exception being lost because no exceptions are throws, I have alot of trace information and I always see complete method calls through ejbCreate, ejbStore, et. al.
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a bit scarie for something that may one day be in production.

What are the entities that can be re-used in different servers, SI App, SI instance? And how?

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On the presentation titled "04 – Installing, Deploying and Maintaining the SQL Server 2008 R2 StreamInsight Runtime Engine" with file name SQL10R2UPD05-DECK-04.pptx on ecn.channel9.msdn.com/o9/learn/SQL2008R2TrainingKit/Presentations/SQL10R2UPD05-DECK-04/SQL10R2UPD05-DECK-04.pptx
It is mentioned one of the deployment option is "Deployment: Standalone Server"
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- Adapter Types
- Query Templates
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Could you please provide good example that explain the above statement?
Cheers, Muhammad

First, that statement - and those materials - refer to the "legacy" StreamInsight query/adapter model. They do not refer to how things work with the Reactive model introduced in version 2.1. Specifically, it talks about Dynamic Query Composition (DQC).
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Typically, however, applications act as containers (comparable to .NET AppDomains) so I don't think that you'd be able to do this easily. That said, the code and assemblies
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Can you be more specific about your use case and what you are trying to accomplish here? It's possible that there are alternative ways to do what you are trying to do.
DevBiker (aka J Sawyer)
Microsoft MVP - Sql Server (StreamInsight)
If I answered your question, please mark as answer.
If my post was helpful, please mark as helpful.

Ejb - BMP Finder

Hello,
I wrote an appliation which connects to EJB.
I use BMP, and wrote a finder in the CustomerBean which sets
records of customers table to a com.borland.dx.dataset.DataSetData (which is serializable)
I tried to do this:
public DataSetData ejbFindAll() throws FinderException {}
but I get an error that a finder can't return a DataSetData,
only a collection or the bean.
can I write other function which will return DataSetData,
and to write it's definition in the Home interface?
it means not using finders.
Thanks.

Thanks for your reply.
According to your reply, I shouldn't use Entity Beans,
only remote Session Beans.
Is it accepted to write in this way, while using the
EJB technologic?
I write an applet GUI, which contains swing and borland
components like JdbTable.
It will take a long time to add the records to the collection
in the Entity Bean,
and move the collection to dataset in the applet.
I will be happy to hear your advice.
Thanks,
Anat

EJB bmp persistence

hi,
I was reading tutorials on BMP.
I found that in all the tutorial they have mentioned that it involves writting queries ourself.
So by using a BMP means 'writing the query alone' or is there any service that has to be provided.
Also can u broach me abt the services that are taken care in a CMP.

There some limitations of CMPs.. Some of them are..
1. Limitations of type of data sources that may be supported by a container for CMPs
2. EJB QL cant handle complex queries
Some advantages..
1. easier to create/manage than BMPs
2. If you need CMR then you may need to use CMPs
3. Optmization of SQL by containers
venkk
http://www.venkks.net/

EJB BMP slow?

Hello,
I don't understand why people use EJB's if it is so slow. I am trying
to do simple GET and SET methods on the current bean in memory, where
each GET and SET method calls ejbLoad() and ejbStore() which are
extremely resource intensive so they are very slow. Are there ways
around this?
I don't see why someone would want to do use EJB's when it is so
slow...doesn't make sense. I must be missing something. Anyone?
Tim :-)

ck388 <[email protected]> wrote:
I don't understand why people use EJB's if it is so slow. I am trying
to do simple GET and SET methods on the current bean in memory, where
each GET and SET method calls ejbLoad() and ejbStore() which are
extremely resource intensive so they are very slow. Are there ways
around this?
I don't see why someone would want to do use EJB's when it is so
slow...doesn't make sense. I must be missing something. Anyone?using bmp, it's up to you to optimize the expensive db calls.
keep a dirty bit for each field and only commit it in your ejbStore
when it's actually been changed, etc.
if your object-relational mappings are not complex, you can bind your
entity to the db through cmp, and then the container does the sql and
the optimizations for you.
____________________}John Flinchbaugh{______________________
| [email protected] http://www.hjsoft.com/~glynis/ |
~~Powered by Linux: Reboots are for hardware upgrades only~~

URGENT---EJB 3.0--Toplink essential - loading custom session customizer

Dear all,
I am a newbie to EJB as well as JPA...for some reason i need to write a custom session customizer
i config the persistence.xml with the following property:
<property name = "toplink.session.customizer" value = "customizer.MyCustomizer"/>
My EJB project structure:
Application1
->EJB_Project1
->customizer
->MyCustomizer.java
->bean
->BeanARemote.java
->BeanBRemote.java
->META-INF
->persistence.xml
when i want to test the EJB project..the following exception occur...
==============================================================
Exception Description: ClassNotFound: [customizer.MyCustomizer] specified in [toplink.session.customizer] property.
Internal Exception: oracle.classloader.util.AnnotatedClassNotFoundException:
Missing class: customizer.MyCustomizer
Dependent class: oracle.toplink.essentials.internal.security.PrivilegedAccessHelper
Loader: oracle.persistence:1.0
Code-Source: /C:/Oracle10-1-3-11/toplink/jlib/toplink-essentials.jar
Configuration: <code-source> in /C:/Oracle10-1-3-11/jdev/system/oracle.j2ee.10.1.3.39.14/embedded-oc4j/config/server.xml
This load was initiated at oracle.persistence:1.0 using the Class.forName() method.
The missing class is available from the following locations:
1. Code-Source: /G:/JDeveloper/jdev/mywork/Application1/EJB_Project1/classes/ (from <ejb> in unknown)
     This code-source is available in loader current-workspace-app.root:0.0.0.
     This is the current thread's context loader, and it appears that Class.forName() was used to load the dependent class.
     If a loader was not explicitly passed to Class.forName(), try passing the result of calling Thread.currentThread().getContextClassLoader().
==============================================================
the application server cannot load the class but it can locate where the class is...
why???
i futher check if the problem is related to parent-child class-loader mechanism
in the code, i call the Class.getClassLoader() in order to obtain which classloaders
my session customizer and JPA EntityManager (implied for the whole toplink essential?) were loaded by...
result: for custom session customizer..
top classloader == jre.bootstrap:1.5.0_09
2nd classLoader == jre.extension:0.0.0
3rd classLoader == api:1.4.0
4th classLoader == oc4j:10.1.3
5th classLoader == system.root:0.0.0
6th classLoader == default.root:0.0.0
result: for JPA EntityManager..
top classloader == jre.bootstrap:1.5.0_09
2nd classLoader == jre.extension:0.0.0
3rd classLoader == api:1.4.0
4th classLoader == oc4j:10.1.3
it seems the EntityManager is loaded in 'higer level' class loader, so it can't access
class load in 'lower level' class loader ..
Dependent class: oracle.toplink.essentials.internal.security.PrivilegedAccessHelper
Loader: oracle.persistence:1.0But something strange is that the exception message saying the loader is oracle.persistence:1.0 ???
Could anybody help me......?
what is the solution...?
i have searching in the web for days but can't find solution !!!
Thank you very much ...
** My development environment:
JDeveloper: 10.1.3.1
window xp sp2
sun java sdk 5 update 9

i have futher check if the problem is related to class loading
i call the Class.getClassLoader() in order to obtained which classloaders
my session customizer and EntityManager were loaded...
obtain the following result: for my session customizer..
top classloader == jre.bootstrap:1.5.0_09
2nd classLoader == jre.extension:0.0.0
3rd classLoader == api:1.4.0
4th classLoader == oc4j:10.1.3
5th classLoader == system.root:0.0.0
6th classLoader == default.root:0.0.0
for EntityManager..
top classloader == jre.bootstrap:1.5.0_09
2nd classLoader == jre.extension:0.0.0
3rd classLoader == api:1.4.0
4th classLoader == oc4j:10.1.3
it seems the entity manager is loaded in 'higer level' class loader, so it can't access
class load in 'lower level' class loader ..
Dependent class: oracle.toplink.essentials.internal.security.PrivilegedAccessHelper
Loader: oracle.persistence:1.0But something strange is that the exception message saying the loader is oracle.persistence:1.0 ????
Could anybody help me......?
what is the solution...?
Thank you ...

URGENT : ejb client in Oracle 8

We developed a EJB client. This client should be called from an Oracle Database 8.1 (ejb compliant). But, each time we tried to load weblogic.jar, we have several errors into Oracle (ie : ORA-29534 NamingContext could not be resolved)
Do you have an idea why ? Someone already developed an ejb client into Oracle 8.1 ?

They are reccomended because the next step going from your simple single EJB
to anything interesting, like adding more EJB's adding web-apps, adding
web-services etc etc involves ears. If the setup and overhead for an EAR is
easy, then just start there.
But no if you just doing helloworld you of course dont have to ears.
cheers
mbg
"Christopher R. Gardner" <[email protected]> wrote in message
news:3fc0560e$[email protected]..
>
"Mark Griffith" <[email protected]> wrote:
You can still run ejbc from the command line its still there. And you
can
still run weblogic.Deployer. (I dont ever reccomend jaring up in dev,
it
just takes longer, do exploded its easier and faster).
But ear's are easy, see:So ears are recommended even if you're just doing EJBs (e.g., a simpleHello World)
and no web apps (none needed for the Hello World or a PC client)?
http://www.niffgurd.com/mark/work/blog/
Cheers
mbg
"Christopher R. Gardner" <[email protected]> wrote in message
news:3fbfd6c6$[email protected]..
My understanding is ejbc has been deprecated and replaced with appc.Moreover,
BEA is encourgaging developers to deploy ear files. All I want todo is
to use
ant to deploy a jar file with a single EJB in it. I'm not findingthe WL
documentation
very helpful. Hopefully, you'll have better luck than I.
"skmurali" <[email protected]> wrote:
Hi
In order deploy EJB application in Weblogic 8.1, is it necessary
to compile
the application in WebLogic.ejbc. I did not find such files in
WebLogic
8.1
In weblogic 7.0 versiion has such files.
The present procedure is as follows.
1. Create a jar file contains all class files.
2. Create a jar file contains class jar files, plus .xml files
3. Deploy into weblogic 8.1 server EJB Deployment utility.
==================
Please help me.
Murali

Urgent: EJB Transaction mechanism and Database Transaction mechanism

Anybody please clarify me how EJB transaction mechanism use the underlying database transaction mechanism? Here my concern is that in the context EJB transaction, how much reponsibilities are performed by EJB container and how much responsibilities are performed by underlying database server. I will deem it a great favor if you kindly explain the whole story with example(s).

Actually the ejb container is managing the persistence.
It will be like this.
if u r using entity beans or statefull beans
while creating entity bean class you have to specify in the
deployment descriptor, which table in the database this bean is representing .
On the runtime , when you are creating an instance of a entity bean ,that instance will be corresponds to a row in the mapped table.
what all changes you have made to that instance's attributes ie;
columns in that row that all will be avilable in the session
When you commit this particular session .this changes will be written to disk.
that's how the change is managed ...
assume if one user is modifying the particular row and another user is deleting it ..which ever transaction commits first will be get effected.
if modification is committing first and then delete the row will be deleted last.but if first delete and then modify while commiting modifycation..
you should get an error saying that particular row is missing from storage
this how ejb container is manging the persistence
in all cases even in case of synchronus acess
i think u r cleard with this much

Urgent EJB help

Hello Java Gurus,
i have some questions, please some help :)
1. What is the difference between ejbCreate() found in the Bean class & the create() method found in the Home object. (Is there a difference in functionality ? )
2. I hear some developers say the "EJB class", do they mean the Bean class ??
3. SessionContext , can we use it to get & set attributes as the regular Session object that we create in a servlet or in a jsp ?? Or is there a difference
Thanks in advance :)

Hello Java Gurus,
i have some questions, please some help :)
1. What is the difference between ejbCreate() found
in the Bean class & the create() method found in
the Home object. (Is there a difference in
functionality ? )The Home.create() is the client-visible API. ejbCreate is the implementation
of that method on the bean class which is invoked by the ejb container.
>
2. I hear some developers say the "EJB class", do
they mean the Bean class ?? Yes.
>
3. SessionContext , can we use it to get & set
attributes as the regular Session object that we
create in a servlet or in a jsp ?? Or is there a
differenceNo, SessionContext is a special object only usable within a session bean.
It's a special API between the bean class code and the ejb container.
E.g. if a bean uses container-managed transactions it can set the
transaction for rollback-only using SessionContext.
--ken
>
Thanks in advance :)

URGENT : EJB + SQLJ Exception

Hi,
I have done an EJB and i have published it in Oracle8i.
Everything seem to work well but when i call it from the client
i have got the following error:
D:\Oracle\Jdev2\myclasses>java gestoreAccessoClient
java.sql.SQLException: profile accesso.accessoSQLJ_SJProfile0
not found: java.la
ng.ClassNotFoundException: accesso.accessoSQLJ_SJProfile0 for
class accesso.acce
ssoSQLJ_SJProfileKeys
But the Only file i have got with the name
accesso.accessoSQLJ_SJProfile0 it's a .ser file?
I have tried to publish it with the EJB but it didn't solve the
error.
Could someone help me?
Thanks a lot
Luca
null

luca landolfo (guest) wrote:
: Hi,
: I have done an EJB and i have published it in Oracle8i.
: Everything seem to work well but when i call it from the client
: i have got the following error:
: D:\Oracle\Jdev2\myclasses>java gestoreAccessoClient
: java.sql.SQLException: profile accesso.accessoSQLJ_SJProfile0
: not found: java.la
: ng.ClassNotFoundException: accesso.accessoSQLJ_SJProfile0 for
: class accesso.acce
: ssoSQLJ_SJProfileKeys
: But the Only file i have got with the name
: accesso.accessoSQLJ_SJProfile0 it's a .ser file?
: I have tried to publish it with the EJB but it didn't solve
the
: error.
: Could someone help me?
: Thanks a lot
: Luca
Wherever your SQLJ program is run, you'll have to package the
.ser files with it (e.g. in a jar or zip file). This is done
most easily if you use the -d option to specify a class (and ser)
file repository to the SQLJ translator.
In addition to this, you can use the flag: -ser2class that
converts the .ser file to a class file. This may help in some
cases - again, make sure to package the resulting class file.
-- Ekkehard
null

Add ejb.jar as a module into ear using jdeveloper

hi all,
i have problem with ejb.jar file.
i want to add one ejb.jar module into jdeveloper application.
I means i want to add into ear as dependencies.
right now, I can only add jpr project as dependencies.
Unfortunately my ejb.jar dont have source file.
how can we achieve this?
With Regards,
WP

OK, here is a working solution which I finally found myself:
1. register the ejb references in the consuming web application manually (in web.xml)
2. add the interfaces jar to the app APP-INF/lib file group (Application Libraries)
3. add a new file group for libraries and add the ejb jar library (should be among the dependencies of some project to be available)
4. the path in ear field should be empty so the ejb jar goes into root, but JDeveloper (11.1.1.4-6) in it's amazing helpfulness fills in lib all the time if field left empty: so edit the .jws xml directy and enter v="" in the according element and make sure to check if still empty whenever editing the profile

URGENT - EJB 2 BMP Entities - Is it OK to use On Delete Cascade?

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