Will updates to an EJB3 entity bean update ONLY changed columns?

Hello,
If you have an EJB3 entity bean that maps to a table, and then you change the value of ONE of the fields in the entity bean, will each column in the row be updated, OR just the column that changed in the row?
Thanks

Only fields detected as persistent-dirty will be updated in the database record.
Laurent

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EJB3 entity bean update, best practice

I have an ejb3 entity bean that models a time that can be reserved in a booking system.
I need a way to reserve the time for a specific user. Ofcourse the reservation should not overwrite if the time has already been reserved by another user.
What is the best/cleaneste way to provide this service?
I have thought of the following ways.
I could put a version field on the entity. When the user is set in the frontend the entitybean will check that the time is not already reserved. If not it will be sent backup to the stateless session bean for persisting. If the time has been reserved by another user in the meantime JPA will throw an exception since the version doesn't match any more. The frontend can then show the error to the user.
I could make the frontend call a method in a stateless session bean to reserve the time. The function could take the times primary id and the users primary id and loaded them from persistence. Then check if the time is already reserver else set the user and persist the time again. This should ofcourse be within a transaction and possibly also use a version attribute on the entity.

Only fields detected as persistent-dirty will be updated in the database record.
Laurent

CMP entity bean update after database update

I'm new to JDeveloper and J2EE. Since JDev 10.1.3 is now production software I finally got started with it. Everything was quite simple to achieve however I have one problem.
My current setup is faily easy. I have a statelss session bean and a CMP entity bean using TopLink (both EJB 2.1). Getting them both created went smooth and having the two talk was as easy as pie thanks to Jdev.
The problem I have is with the entity bean. I'm using a custom finder method to retrieve records using non-PK fields. This works like a charm and I'm getting the data I need. But when I update the data in the database (OracleXE) and I rerun the client I get the old data. The only way for me to get new data is to restart the embedded OC4J server in JDev.
How can I have the entity bean updated by changes in the database?

Thanks Avi!
I spent some time with the documentation and I see I can configure the cache. However how to do this is not clear to me. I have the impression that most of it relates to BMP entity beans.
Apparantly there is a DoNotCheckCache method I can invoke on the query, but I have no idea how to achieve this...
Message was edited by:
Deddiekoel

Will my phone get a jelly bean update........???

im soo sad that my got damn slow .....sice i ve updated my phone to ics .......i feel that ......gingerbread holds my phone good ......
But still... will my phone get a jelly bean update..???? ..........so that it overcomes the probs of ics..................

Let me answer you ony have just gave out a speech about the "error" of their words. Since then, they stopped speech about it. I bet it's the truth that Xperia 2011 wont get an update, they just want to calm us down

Ejb3 entity bean not generating valid sql for postgres 8.1

Hello,
I originally posted this on the jboss seam board as I ran across this error on a seam test example, but it seems it's more generally applicable to ejb3 entity beans not generating sql that postgres can understand. I'll post my message below, all replies are appreciated.
I'm going through the hello world example from the seam book, and I'm getting an error I cannot resolve, that with an auto generated sql statement, that's not valid for postgres 8.1, the database I'm on. Here's my error:
17:40:31,370 INFO [STDOUT] Hibernate: select next value for person_id_seq from dual_person_id_seq
17:40:31,394 WARN [JDBCExceptionReporter] SQL Error: 0, SQLState: 42601
17:40:31,394 ERROR [JDBCExceptionReporter] ERROR: syntax error at or near "value"
17:40:31,396 FATAL [application] javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not get next sequence value
javax.faces.el.EvaluationException: javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not get next sequence value
Here's the table definition
- create table Person (id bigint not null, name varchar(255), primary key (id))
- create table dual_person_id_seq (zero integer)
- create sequence person_id_seq start with 1 increment by 1
and here's the entity bean:
@Entity
@Name("person")
@Table(name="person")
@SequenceGenerator(name="person_sequence", sequenceName="person_id_seq")
public class Person implements Serializable {
private long id;
private String name;
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator="person_sequence")
public long getId() { return id;}
public void setId(long id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
How do I get it to generate a valid sql statement for postgres?

I think you should try putting the sequence generator annotation over the primary key field. Try it and be sure it works.
regards,
Michael

Entity Bean can only use container-managed transaction demarcation?

In <<Designing Enterprise Application with J2EE 2nd>>
Section 2.3.3.3 Enterprise Bean Transactions,it says:Entity beans can only use container-managed transaction demarcation.
That means,i can not get UserTransaction from EJBContext.
Is that true?

Yes this is the requirement of the specs. Your ejb code generator should give you the error if you use usertransaction.
--Ashwani

Does an entity bean update result in ALL DB columns being updated?

Hello,
If I update a single field in my entity bean, will all the columns for the DB row be updated? -OR will only the changed column value be updated?
Thank,
Keith

Only fields detected as persistent-dirty will be updated in the database record.
Laurent

What happens to cached entity beans when directly change record in database?

hi:
i am working on a project which weblogic as app server. there's many case
in my application where we have to update large number of records(about
fifty thousands) in
a loop one at a time. we have tried with entity beans but it 's so slow.
so in this case we have to update database directly. but i am worried about
my code accessing record with entity beans. the entities caches state and i
am
afraid there will be trouble if the state in ejb caches and record in db
mismatch . i change state in db directly and ejbs has no way to know about
it.
is there any solution?
thanks in advance!
daniel

Depends on the way you have implemented your entity bean. Normally, a bean
method invocation will trigger a transaction (based on the bean's method
transaction attribute), which will in turn call the ejbLoad(). In CMP's the
container will automatically load the data from the underlying datastore. In
BMP's a transactional method call will invoke the ejbLoad(), and the
ejbLoad() implementation would be responsible for loading the data.
"daniel wang" <[email protected]> wrote in message
news:3c5e01b9$[email protected]..
hi:
i am working on a project which weblogic as app server. there's manycase
in my application where we have to update large number of records(about
fifty thousands) in
a loop one at a time. we have tried with entity beans but it 's so slow.
so in this case we have to update database directly. but i am worriedabout
my code accessing record with entity beans. the entities caches state andi
am
afraid there will be trouble if the state in ejb caches and record in db
mismatch . i change state in db directly and ejbs has no way to know about
it.
is there any solution?
thanks in advance!
daniel

How to achieve Entity Bean methods ONLY by calling them from a Session Bean

Hi,
I used a session bean as a business facade to a entity bean.
In the session bean I achieve the entity bean with a jndiContext.lookup("java:comp/env/ejbEntityBean").
Now I am looking for a solution that it is only possible to call the entity bean methods or the whole entity bean from the corresponding session bean.
In other words: "How can I forbid the access to the entity bean, if the calling object is not the corresponding session bean?"
--->
I only found a way the regulate the access to the entity bean methods by declaring a security-role.
But the existence of the security-role at runtime depends on the calling user-authorizations!
Is there a way to set the entity-security-role within the session bean context?
Best Regards
Steffen

Hi Srikanth Reddy.T,
sorry, I am not looking for a special tag <entity-security-role>.
I am looking for a way to specifiy that my session bean "has" the special security-role (in my case "WebZaehlerEjbRole") of my entity bean "in my case "WebZaehlerEjbRole") that is necessary to call the methods (findAlleEntries, findByWindowId,...) of my entity-bean.
Here is the relevant part of my ejb-jar.ml:
     <assembly-descriptor>
          <security-role>
               <role-name>WebZaehlerEjbRole</role-name>
          </security-role>
          <method-permission>
               <description>method-permission</description>
               <role-name>WebZaehlerEjbRole</role-name>
               <method>
                    <ejb-name>WebZaehlerBean</ejb-name>
                    <method-name>findAllEntries</method-name>
                    <method-params/>
               </method>
               <method>
                    <ejb-name>WebZaehlerBean</ejb-name>
                    <method-name>findByWindowId</method-name>
                    <method-params>
                         <method-param>java.lang.Long</method-param>
                    </method-params>
               </method>
Regards,
Steffen

Does Update statement update only changed columns?

Let's say I have TABLE1 with columns ID NUMBER(2,0),FNAME VARCHAR2(20),LNAME VARCHAR2(20), AGE NUMBER(2,0). I insert a new record:
INSERT INTO TABLE1 (ID,FNAME,LNAME,AGE) VALUES(1,'Steve','Jobs',40);
then I say:
UPDATE TABLE1 SET FNAME='Steve', LNAME='Jobs',AGE=56 WHERE ID=1;
As you see only the value of AGE column is different but in the UPDATE statement I still set the other columns to the previous values to. I wonder if Oracle is smart enough to update only the AGE column or does it update all the columns?

I don't think that Oracle is making this check: it simply updates columns as specified in the SQL statement.
Here is a 5 year old J. Lewis article that explains why Oracle is working this way: http://jonathanlewis.wordpress.com/2007/01/02/superfluous-updates/.

EJB3 Entities Not Updating

I don't know if anyone else is seeing this or has a resolution, but occasionally when I update an EJB3 entity bean my local OC4J 10.1.3.3.0 will not update the bean and continue hold on to a previous version, even after changes have been made.
I have started/stopped the server multiple times, and deployed/undeployed the application multiple times. I was able to make my changes on a co-workers machine and it works fine there...
Any tips or ideas?

Hi,
See this Support Article for Error 3259:
http://support.apple.com/kb/TS2799

[EJB3 - ADF Faces] entity bean design

Hello,
I have an existant application that use database view (very complex) to retrieve and display values from some tables.
I have to reproduce the same thing with EJB3 ans ADF Faces in a web application.
What is for you the best way to design entities beans ?
1. Create some buisness objects (entity beans) and feed them with a query thru the database view ?
2. Create a unique entity bean with only attributes who are used by the db view ?
In this case, the entity bean will be used only for this query.
3. ?
I think the best solution is the first one.
But in this case, how to display the result of the query in an ADF Faces table?
With the 2nd solution the query returns a list of object which will be used by the adf table. That would be much easier.
Thanks for your help.

The popup dialog is used for looking up a value of fields on the form. I have fields "location id" and "sub location id", the popup has cascading drop down lists where I choose which ones I want, then return those values from the popup and display the selection in readonly text inputs. Other inputs also exist on the form. Together they all make the input parameters to the session facade's query.

Creating entity beans (EJB3) from xml schema

Dear friends,
I have a XML schema.. and I want to implement an Enterprise application with EJB3 Entity Beans exposed through a set of JAX-WS Web-Services...
question: how to define the entities from the XML schema?

Two alternatives:
1) JAXB 2.0 generates POJOs with JAXB annotations in them. You can take ownership of those POJOs and add Java Persistence API annotations in them by hand. Basically, you will end up having both both JPA and JAXB annotations in the same Java class. You can then use them in your code both with JAXB APIs and JPA APIs.
2) Have a look at http://hyperjaxb3.dev.java.net/ It is trying to automate what I described in #1. The project is still not complete, so right now, you may have to hand code the JPA annotations.
Sahoo

Error when deploying a simple Entity bean (EJB3) on Glassfich or Sun AS

Hi,
After some problems when deploying complex EJB3 Entity bean on GlassFich with a MySQL connector, I have made a simple entity.
(test with Glassfish and Sun AS with same result)
With netbean 5.5 => New EJB Module
File->New->Persistence Unit (and use default values)
Persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="test" transaction-type="JTA">
   <provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
    <jta-data-source>jdbc/sample</jta-data-source>
    <properties>
      <property name="toplink.ddl-generation" value="create-tables"/>
    </properties>
</persistence-unit>
</persistence>File->New->Entity Class
EntityTest.java
package test;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class EntityTest implements Serializable
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    /** Creates a new instance of EntityTest */
    public EntityTest()
    public Long getId()
        return id;
    public void setId(Long id)
        this.id = id;
    public String toString()
        //TODO change toString() implementation to return a better display name
        return "" + this.id;
}Build of project work fine but when I try to deploy (with the 2 servers), I have the error :
Exception occured in J2EEC Phase
com.sun.enterprise.deployment.backend.IASDeploymentException: Deployment Error -- null
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:790)
at java.util.HashMap$KeyIterator.next(HashMap.java:823)
at com.sun.enterprise.deployment.backend.EjbModuleDeployer.generatePolicy(EjbModuleDeployer.java:203)
at com.sun.enterprise.deployment.backend.ModuleDeployer.doRequestFinish(ModuleDeployer.java:171)
at com.sun.enterprise.deployment.phasing.J2EECPhase.runPhase(J2EECPhase.java:169)
at com.sun.enterprise.deployment.phasing.DeploymentPhase.executePhase(DeploymentPhase.java:95)
at com.sun.enterprise.deployment.phasing.PEDeploymentService.executePhases(PEDeploymentService.java:871)
at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:266)
at com.sun.enterprise.deployment.phasing.PEDeploymentService.deploy(PEDeploymentService.java:739)
at com.sun.enterprise.management.deploy.DeployThread.deploy(DeployThread.java:174)
at com.sun.enterprise.management.deploy.DeployThread.run(DeployThread.java:210)

Yes, the problem is that the ejb-jar must contain at least one ejb component. It's a common misconception that Java Persistence API Entity classes are ejb components but they are NOT. The Java Persistence API was developed within the EJB 3.0 JSR and works very well with EJB but the entity classes themselves are not full-fledged ejb components.
--ken

Use direct JDBC with CMP entity bean in one transaction

I am trying to use direct JDBC call with CMP entity bean within a session
bean method that requires transaction. The problem is that it appears these
are not in the same transaction. When I use the JDBC call, the CMP entity
bean update to the DB has not been committed yet.
We are using Weblogic 5.1 SP6. The DB is Oracle.
What I do for the JDBC is get a new connection from the pool using weblogic
jdbc pool driver.
Any help would be appreciated.
Patrick

Hi. You can do JDBC and invoke CMP EJBs and have this all treated
as one transaction, if your hand-written code explicitly starts
a JTS transaction, then uses the jts driver or a TxDataSource to
get the JDBC connection. Then your code can call transactional
EJBs and their work will be included in the transaction you started.
Assuming the bean work went OK, and your manual JDBC went OK, you
can manually commit the UserTransaction at that time. This is 5.1
talk. For 6.0, with @PC, this may be even easier...
Joe
Patrick Shen wrote:
>
But if I do that, then they would not be in the same transaction anymore.
Is there any way to use JDBC with CMP Entity bean in the same transaction?
Patrick
"L'artiste" <[email protected]> wrote in message
news:[email protected]...
Are you calling all the CMP create in the session Bean ? If so, beforeyou
make the JDBC call from the session bean, the CMP in 2. should commit. Try
to set its attribute to TX_REQUIRES_NEW. This way, the calling client will
block until this transaction is done (committed) before the execution
continues. There might be some overhead involved in doing so if you are
anticipating a lot of users.
"Patrick Shen" <[email protected]> wrote in message
news:[email protected]...
What I am trying to do is:
In a Session bean method -
1. create a new CMP entity bean (a new row in DB table)
2. create another new CMP entity bean that uses previous bean as foreignkey
3. use JDBC to update the row just created
And all these 3 calls have to be in one transaction.
Thanks,
Patrick
"L'artiste" <[email protected]> wrote in message
news:[email protected]...
Can you give a little bit more information?
Do you have methods in your session bean that creates this CMP entitybeans?
It looks like
you might wanna try to change the isolation level to
TRANSACTION_READ_COMITTED
to preven dirty_read.
"Patrick Shen" <[email protected]> wrote in message
news:[email protected]...
I am trying to use direct JDBC call with CMP entity bean within a
session
bean method that requires transaction. The problem is that it
appears
these
are not in the same transaction. When I use the JDBC call, the CMP
entity
bean update to the DB has not been committed yet.
We are using Weblogic 5.1 SP6. The DB is Oracle.
What I do for the JDBC is get a new connection from the pool usingweblogic
jdbc pool driver.
Any help would be appreciated.
Patrick
PS: Folks: BEA WebLogic is expanding rapidly, with both entry and advanced positions
for people who want to work with Java, XML, SOAP and E-Commerce infrastructure products.
We have jobs at Nashua NH, Liberty Corner NJ, San Francisco and San Jose CA.
Send resumes to [email protected]

Will updates to an EJB3 entity bean update ONLY changed columns?

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