Are EJB ( entity beans) are cached ?

Are EJB ( entity beans) are cached ?
I have a doubt here . As per my understanding , the entity beans are cached from the database. In that case , If I delete a row in the database by an external application ( say using TOAD tool) , how the Entity bean will be updated / reloaded ? Entity bean will be out of sync then .
Application server : weblogic/webspehere .

>
You can use the refresh method of the EntityManager interface to read new values from the database (if you expect it to be out of sync), and use locks to prevent others from changing your data while the application is performing actions in a transaction.Did you mean I have to write code for this ? can't be made it automatic refresh by the container ? Is there any settings I can configure so that container can do it by itself proactively ?
Also, using locks ...is this a container settings or I need to configure myself in ejb-jar.xml ? Could you please shed some light here ?

Similar Messages

Rad-only Entity beans are replicated?

Hi. I have just read the document "Failover and Replication in a cluster": http://edocs.bea.com/wls/docs81/cluster/failover.html#1008850
I have no clear if read-only entity beans are replicated?
I understand that replica-aware stub does not mean that stub objects are replicated in all the servers of the cluster. This seems to be only for statefull session beans.
Thx.

Hi,
we use read only entity beans. It is beneficial if have findByPrimaryKey finders. but we also have finders on non primary key coloumn also. is there a way to cache such local references returned by such non primary key finders also.

Are ENtity Beans are deprecated in 3.0 version

Hi the below line is from the book "Mastering EJB 3.0 "
Note that Entity beans havent been enhanced in ejb3.0 , since there have been no changes made to them .
What does this mean actually ?
Does it mean ENtity Beans are deprecated in 3.0 version ?

>
Hi kiran7882,
Note that Entity beans havent been enhanced in ejb3.0 , since there have been no changes made to them .Entity beans are specific to persistence managers. EJB's are only modules which can use them like any other objects.
Does it mean ENtity Beans are deprecated in 3.0 version ?No.

EJB entity beans and BC4J

I have looked at BC4J and it looks good. Buy my question is that isn't this frame work in direct conflict with EJB entity beans. I know lot of stuff that is there in BC4J should have been in EJB enitiy beans, but as a developer why should I go with BC4J and not the standard EJB stuff considering the fact that BC4J is properietery to Oracle?Any thoughts?

Vimal,
Without going into exhaustive detail here, I would like to recommend that you take a look at the BC4J Technical White Paper available from the JDeveloper page on OTN (in the 3.0 Technical Information section):
http://technet.oracle.com/products/jdev/info/techwp20/wp.html
Amoung other things to note, BC4J is based on pure Java, and is what we consider a 'white box', meaning, you as a developer have complete control over what is going on. You can extend any of the code generated to customize it.
Primarily though, the major benefit of BC4J is that we have taken care of most of the complicated communication code for you. Communication between the client and the data server, transaction handling, row locking, etc are already written for you. You just use, extend, customize what we have provided.
In addition, BC4J allows you flexibility in your deployment environment decision. Regardless of where and how you deploy your BC4J Application Module, the client is unchanged.
Those are the key advantages. Again, for more details, I would take a look at the white paper to see if it more fully addresses your questions.

EJB Entity Beans

"Entity Beans are suitable for read/write database access when transaction control
is important. Container managed Entity beans should be suitable for simple entity
relationships and offer much easier maintenance and development."
Tell me why or why not you agree with the above statement.
This is one of the most talked about issues, and I like to see this group's view
point, regardless of what Sun says in their blueprint.
On a unrelated note, i like to see what you think about this:
What are the benefits and disadvantages of using Inner Classes?

I agree. How are you gonna find the marks without primary key? Sequential seek??
What you should do is having student_id as primary key of the marks table and create a 1-* relationship between them by student_id.
Cheers.

How to delete a database record by using EJB entity beans

Hi, All,
Does anyone know how to use entity bean to delete a database record? I have all the EJB entity beans created, including access beans to each. I can successfully create records, find and update records, however, I haven't find a way to delete records yet.
Your response is appreciated.
Cathy

Please see EJB Forums for continue discussion on this subject.
Reference titile: "how to delete database record by using CMP entity beans "

Does JServer support EJB/Entity beans

What version of JServer lives in the following applications, and does it support EJB/Entity Beans or when will it.
8.1.5 OAS
8.1.5 8i
8.1.6 OAS
8.1.6 8i

Check out the following link for details about the Beta Program: http://technet.oracle.com/products/oracle8i/java_beta/index.htm
New features that will be available in the Beta include support for Entity Beans, and support for Servlets. It also includes JServer Accelerator (JServer's Native Compiler).

Problems accessing tables in oracle database with ejb entity bean

I have created a simple server application that uses an entity bean (version 2.0) for an existing table in oracle database, and a session bean that is used as an outside interface for performing operations on that table.
after deploying the server and client application the client attempts to perform an operation with the session bean remote interface it obtained.
The session bean uses a locale interface to communicate with the entity bean, but when it tries to use its methods (create, findByXXX) it always get the following Exception: java.sql.SQLException: ORA-00942: table or view does not exist.
the table of course exists, and the username password I'm using has all the permissions needed for this table.
note - I'm using the Forte enterprise edition 4.0 as developer tool.
I'll be glad to get some help.
Here is the full stack trace of the exception:
javax.ejb.TransactionRolledbackLocalException: Exception thrown from bean; nested exception is: javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
java.sql.SQLException: ORA-00942: table or view does not exist
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:168)
at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:208)
at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:543)
at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1405)
at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteDescribe(TTC7Protocol.java:643)
at oracle.jdbc.driver.OracleStatement.doExecuteQuery(OracleStatement.java:1674)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1870)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:363)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:314)
at com.sun.ejb.persistence.SQLEngine.ejb20Finder(SQLEngine.java:226)
at com.sun.ejb.persistence.PartitionImpl.ejbFinder(PartitionImpl.java:736)
at com.cti2.telco.core.ejb.entity.userInfo.UserInfoEJB_PM.ejbFindByEmail(UserInfoEJB_PM.java:393)
at com.cti2.telco.core.ejb.entity.userInfo.UserInfoEJB_PM_LocalHomeImpl.findByEmail(UserInfoEJB_PM_LocalHomeImpl.java:64)
at com.cti2.telco.core.ejb.UserManagerEJB.authenticate(UserManagerEJB.java:77)
at com.cti2.telco.core.ejb.UserManagerEJB.authenticate(UserManagerEJB.java:68)
at com.cti2.telco.core.ejb.UserManagerEJB_EJBLocalObjectImpl.authenticate(UserManagerEJB_EJB
LocalObjectImpl.java:63)
at com.cti2.telco.core.ejb.dispatch.TelcoFacadeEJB.userLogin(TelcoFacadeEJB.java:80)
at com.cti2.telco.core.ejb.dispatch.TelcoFacadeEJB_EJBObjectImpl.userLogin(TelcoFacadeEJB_EJBObjectImpl.java:24)
at com.cti2.telco.core.ejb.dispatch._TelcoFacadeEJB_EJBObjectImpl_Tie._invoke(Unknown Source)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.dispatchToServant(GenericPOAServerSC.java:519)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.internalDispatch(GenericPOAServerSC.java:204)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.dispatch(GenericPOAServerSC.java:112)
at com.sun.corba.ee.internal.iiop.ORB.process(ORB.java:273)
at com.sun.corba.ee.internal.iiop.RequestProcessor.process(RequestProcessor.java:84)
at com.sun.corba.ee.internal.orbutil.ThreadPool$PooledThread.run(ThreadPool.java:99)
...

Well it seems like the problems has a simple explanation. The Forte assigns a default table name (<entityName>EJBTable) when creating an entity bean from an existsing table in DB (which is not the same as the one it was created from !!!). Also, for reason unknown, when you deploy these entity beans, it doesn't even create the new table under its new name (even if instructed to).
So using the Forte we managed to use successfuly only entity beans that were created "from scretch" (when deployed their tables are created).
Does anyone know how to change the default name the Forte uses, and make it work properly with entity beans created from an existsing table (without going over the xml's) ?

Problem deploying EJB entity bean

Hi all!
I'm trying to deploy an CMP entity bean with composite primary key.
My environment is Oracle 8i (8.1.7) on W2K Professional and I'm using JDK 1.3.1_02.
The error I get is:
Compiling Stubs...done
Generating Jar File...done
Loading EJB Jar file and Comm Stubs Jar file...done
Generating EJBHome and EJBObject on the server...
An exception occurred during code generation: null
I don't understand what am I doing wrong...
Any help will be highly appreciated.
[Could anyone point me out sample code for CMP entity beans with composite primary key?]
Apologies for the length of the POST, just trying to pass as much info as I can...
The table is the following:
CREATE TABLE GPS_HIST (
gps_date_of_fix     VARCHAR2(40) NOT NULL,
gps_time_of_fix     VARCHAR2(40) NOT NULL,
issi               NUMBER(10) NOT NULL,
gps_condition          NUMBER(5),
gps_latitude          VARCHAR2(40),
gps_longitude          VARCHAR2(40),
gps_speed_knt          NUMBER(10),
constraint gps_hist_pk primary key (gps_date_of_fix, gps_time_of_fix, issi))
TABLESPACE AVLDATA
PCTFREE 10     PCTUSED 40
INITRANS 1     MAXTRANS 255
STORAGE (
INITIAL 128K NEXT 128K PCTINCREASE 0
MINEXTENTS 1 MAXEXTENTS 4096)
NOCACHE;
The primary key class is the following:
package gps;
public class GPSEntryPK implements java.io.Serializable
     public int ISSI;
     public String gpsTimeOfFix;
     public String gpsDateOfFix;
     public GPSEntryPK() {}
     public GPSEntryPK (String gpsDateOfFix, String gpsTimeOfFix, int ISSI)
          this.gpsDateOfFix = gpsDateOfFix;
          this.gpsTimeOfFix = gpsTimeOfFix;
          this.ISSI = ISSI;
     public String getGPSDateOfFix()
          return this.gpsDateOfFix;
     public String getGPSTimeOfFix()
          return this.gpsTimeOfFix;
     public int getISSI()
          return this.ISSI;
     public boolean equals(Object obj) {
          if ((obj instanceof GPSEntryPK) &&
               (this.ISSI == ((GPSEntryPK)obj).ISSI) &&
               (this.gpsTimeOfFix.equals(((GPSEntryPK)obj).gpsTimeOfFix)) &&
               (this.gpsDateOfFix.equals(((GPSEntryPK)obj).gpsDateOfFix)))
               return true;
          return false;
     public int hashCode() {
          return (this.gpsTimeOfFix.concat(this.gpsDateOfFix)).hashCode() * this.ISSI;
The bean implemantation (part of it) is as follows:
public void setEntityContext(EntityContext ctx)
this.ctx = ctx;
Properties props = ctx.getEnvironment();
public void unsetEntityContext()
this.ctx = null;
public GPSEntryPK ejbCreate(String gpsDateOfFix, String gpsTimeOfFix, int ISSI, int gpsCondition,
String gpsLatitude, String gpsLongitude, double gpsSpeedKnt)
throws CreateException, RemoteException
try {
setGPSDateOfFix(gpsDateOfFix);
setGPSTimeOfFix(gpsTimeOfFix);
setISSI(ISSI);
setGPSCondition(gpsCondition);
setGPSLatitude(gpsLatitude);
setGPSLongitude(gpsLongitude);
setGPSSpeedKnt(gpsSpeedKnt);
} catch (java.rmi.RemoteException e) {
throw new CreateException();
return null;
public GPSEntryPK ejbFindByPrimaryKey(GPSEntryPK pk) throws RemoteException, FinderException {
return null;
public void ejbPostCreate(String gpsDateOfFix, String gpsTimeOfFix, int ISSI, int gpsCondition,
String gpsLatitude, String gpsLongitude, double gpsSpeedKnt)
     throws CreateException
// get primarykey
GPSEntryPK pk = (GPSEntryPK)ctx.getPrimaryKey();
public void ejbActivate() {}
public void ejbPassivate() {}
public void ejbRemove() {}
public void ejbLoad()
// You can get to the primary key
GPSEntryPK pk = (GPSEntryPK)ctx.getPrimaryKey();
public void ejbStore(){}
The descriptors are the following:
"gpsentry.xml"
<?xml version="1.0"?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems Inc.//DTD Enterprise JavaBeans 1.1//EN" "ejb-jar.dtd">
<ejb-jar>
<enterprise-beans>
<entity>
<description>no description</description>
<ejb-name>GPSEntry</ejb-name>
<home>gps.GPSEntryHome</home>
<remote>gps.GPSEntry</remote>
<ejb-class>gpsServer.GPSEntryBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>gps.GPSEntryPK</prim-key-class>
<reentrant>False</reentrant>
<cmp-field><field-name>gpsDateOfFix</field-name></cmp-field>
<cmp-field><field-name>gpsTimeOfFix</field-name></cmp-field>
<cmp-field><field-name>ISSI</field-name></cmp-field>
<env-entry>
<env-entry-name>realmName</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>gps.realm</env-entry-value>
</env-entry>
<env-entry>
<env-entry-name>GPSEntryBean.databaseURL</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>jdbc:oracle:kprb:</env-entry-value>
</env-entry>
<env-entry>
<env-entry-name>GPSEntryBean.JDBCDriverName</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>oracle.jdbc.driver.OracleDriver</env-entry-value>
</env-entry>
</entity>
</enterprise-beans>
</ejb-jar>
"oracle_gpsentry.xml"
<?xml version="1.0"?>
<!DOCTYPE oracle-descriptor PUBLIC "-//Oracle Corporation.//DTD Oracle 1.1//EN" "oracle-ejb-jar.dtd">
<oracle-descriptor>
<mappings>
<ejb-mapping>
<ejb-name>GPSEntry</ejb-name>
<jndi-name>test/gpsentry</jndi-name>
</ejb-mapping>
</mappings>
<persistence-provider>
<description> specifies a type of persistence manager </description>
<persistence-name>psi-ri</persistence-name>
<persistence-deployer>oracle.aurora.ejb.persistence.ocmp.OcmpEntityDeployer</persistence-deployer>
</persistence-provider>
<persistence-descriptor>
<description> This specifies a particular type of persistence manager to be used for a bean. param is where you would put bean specific persistence info in the format of params. The deployment process just passes what's in the param to the persistence deployer. For the baby persistence, we do parse the persistence-mapping but for other persistence backend we don't do anything with the params </description>
<ejb-name>customerbean</ejb-name>
<persistence-name>psi-ri</persistence-name>
<psi-ri>
<schema>AVLMIS</schema>
<table>gps_hist</table>
<attr-mapping>
<field-name>gpsDateOfFix</field-name>
<column-name>gps_date_of_fix</column-name>
</attr-mapping>
<attr-mapping>
<field-name>gpsTimeOfFix</field-name>
<column-name>gps_time_of_fix</column-name>
</attr-mapping>
<attr-mapping>
<field-name>ISSI</field-name>
<column-name>issi</column-name>
</attr-mapping>
<attr-mapping>
<field-name>gpsCondition</field-name>
<column-name>gps_condition</column-name>
</attr-mapping>
<attr-mapping>
<field-name>gpsLatitude</field-name>
<column-name>gps_latitude</column-name>
</attr-mapping>
<attr-mapping>
<field-name>gpsLongitude</field-name>
<column-name>gps_longitude</column-name>
</attr-mapping>
<attr-mapping>
<field-name>gpsSpeedKnt</field-name>
<column-name>gps_speed_knt</column-name>
</attr-mapping>
</psi-ri>
</persistence-descriptor>
</oracle-descriptor>
Thanks in advance.

Hi Nikos,
I obviously don't know what your entire situation is, but you may not
be aware that Oracle's DBMS embedded EJB container does not work well,
and as a result, Oracle decided to replace it with an external EJB
container which is part of a product called "Oracle Containers for
J2EE" (otherwise known as "OC4J"). The "other" forum (the J2EE forum)
deals mainly with OC4J.
As far as I know, Oracle recommends doing your EJB related work with
OC4J and not with the embedded EJB container.
Good Luck,
Avi. That's correct
Java code, implementing data bound logic, can still run in the database as Java stored procedures/packages/functions/triggers
while J2EE componentsdeployed in middle-tier implement business logic. Java in database enable the database to be an active participant to your deployment platform
in 9iDB R2 you will even be able to call-out Web client (using HTTP Client), EJB client (using oc4jclient.jar) or Web Service client
(using SOAP libraries)
Kuassi

EJB Entity beans ,JDBC Stored procedures

Hi ,
I am new to EJB and i have some general questions
---Every table in an existing database is an entity bean for my application?
--- how do i define the queries in the entity bean ? (With PreparedStatement ?)
---The persistent fields,the ejbmethods,constructors, the table relationships, the prepared statements and stored procedures, are defined in the entity beans ?
--- how do i define the primary Keys in an Entity Bean !!! I will use EJB 2.1 and BMP
thanks in advance ...

Sandeep...
I have dblinks going all over the place. What you are talking about is a clustered or distributed database. That is the future (or present ) of large databases. My code is set up because an 'architecture' is not yet available in the database itself to support the concepts I've posted to Steve in other threads.
I fully believe that we'll eventually have BC4J ( or something like it ) directly in the database. I fully believe that the database will load balance these across a cluster of databases, within the database structure itself. For example... there is NOTHING to stop the JVM from deciding that it needs to load balance and submit the thread to a remote machine for processing... independent of creating a "middle tier" outside the database.
I believed that client-server model was flawed for most (not all) applications in the 80's. Looking at the "application tier" model I have the same feeling that we're creating an overly complex scheme at the wrong layer... just pushed back one stage so that we have to rewrite everything...
If you go back to the megalithic server design ( or cluster of servers ) with a thin thin front end... just why is the middle tier needed under the scenario I've outlined?
As such, stored procedures/triggers be they in java or pl/sql seems best bet to me... seeing's how a call spec to java or a pl/sql wrapper is transparent to the caller using jdbc or any other future technology.
grin Way outside the scope of the universe today... I see it as inevitable.
null

Entity Beans and Caching

Hi,
My environment is:
- Weblogic 5.1 running on Solaris
- Oracle 8i database server
- Two physical servers clustered together to form one logical server
I can possibly upgrade to Weblogic 6 or later if it'll help solve my
problem.
Here's what I'm trying to accomplish:
I want to write entity beans using bean-managed persistence. The BMP
part of it is strongly preferred because our DBAs like to see and tune
all of the queries we send from the application.
In many cases, the data I'm querying is largely static. I want to
write EJBs that will cache the data in memory and avoid reading it
from the database server every time the EJB is invoked, unless it
knows that the data has changed.
I've done this successfully with single-server installations, but I'm
not sure how it'll work with a clustered server. Assuming nothing
outside of my two Weblogic servers is updating my database, can I
configure the EJB to have exclusive access to the database and count
on Weblogic to manage the state between the two servers? Or do I have
to implement some kind of custom signalling scheme so that an EJB in
one container can notify any EJBs in the other container with the same
primary key when it has updated the underlying data?
I know from experience that the container will call the ejbStore()
method whenever a transaction ends. My usual BMP pattern in the past
has been to keep track of whether any data has changed during the
transaction and update only those database columns, if any, that
actually changed. But I don't think the store method has any way of
notifying the container as to whether or not it actually stored
anything; hence, I can't see how the container would know when to
order the entity bean on the opposite server to reload itself.
Thanks.

The 6.1 implements functionality you want:
http://e-docs.bea.com/wls/docs61/ejb/EJB_environment.html#1121105
if you use 5.1 you can use this approach:
http://dima.dhs.org/misc/readOnlyUpdates.html
Frank LaRosa <[email protected]> wrote:
Hi,
My environment is:
- Weblogic 5.1 running on Solaris
- Oracle 8i database server
- Two physical servers clustered together to form one logical server
I can possibly upgrade to Weblogic 6 or later if it'll help solve my
problem.
Here's what I'm trying to accomplish:
I want to write entity beans using bean-managed persistence. The BMP
part of it is strongly preferred because our DBAs like to see and tune
all of the queries we send from the application.
In many cases, the data I'm querying is largely static. I want to
write EJBs that will cache the data in memory and avoid reading it
from the database server every time the EJB is invoked, unless it
knows that the data has changed.
I've done this successfully with single-server installations, but I'm
not sure how it'll work with a clustered server. Assuming nothing
outside of my two Weblogic servers is updating my database, can I
configure the EJB to have exclusive access to the database and count
on Weblogic to manage the state between the two servers? Or do I have
to implement some kind of custom signalling scheme so that an EJB in
one container can notify any EJBs in the other container with the same
primary key when it has updated the underlying data?
I know from experience that the container will call the ejbStore()
method whenever a transaction ends. My usual BMP pattern in the past
has been to keep track of whether any data has changed during the
transaction and update only those database columns, if any, that
actually changed. But I don't think the store method has any way of
notifying the container as to whether or not it actually stored
anything; hence, I can't see how the container would know when to
order the entity bean on the opposite server to reload itself.
Thanks.--
Dimitri

Ejb : entity beans limitations

what are the limitations of bmp & cmp?

"Chinthala Upender" <[email protected]> wrote in message news:28421839.1104135395183.JavaMail.root@jserv5...
what are the limitations of bmp & cmp?According to my experience the main limitation is that engineers are
sometimes reluctant to read books on basics of Enterprise Java Beans.
To overcome this limitation please check this:
http://www.amazon.com/exec/obidos/tg/detail/-/0471417114
Regards,
Slava Imeshev

Caching CMP Entity Beans with 9.0.2

Hi,
my CMP Entity Bean is accessed from a JSP-Page through a Stateless Session Bean. The Session-Bean executes findAll() on the Entity-Bean and the JSP-Page iterates over the Collection and displays the Fields through their getter-Methods. It turns out that every getXXX Methods results in a complete load of the Bean from the Database, so for 3 database-records with 4 attributes i get 12 SELECT - statements and 12 Activate/Load/Passivate cycles of the Entity Bean!!!!
I tried to setup the attributes in orion-ejb-jar.xml correctly, but that didn't show a difference:
-) exclusive-write-access="true" does only work in "read-only" mode (see oc4j_ejb_guide_r2.pdf)
-) setting timeouts didnt work
My Entity Bean settings are:
exclusive-write-access="true"
instance-cache-timeout="60"
max-instances="100"
max-tx-retries="0"
pool-cache-timeout="100"
The EJB-Callbacks are:
first the Session-Bean is created, and findAll() is executed - then all Entity-Beans are passivated again:
TestManBean Constructor called 1
TestManBean.setSessionContext() 1
TestManBean.ejbCreate() 1
PersonBean Constructor called 1
PersonBean.setEntityContext() 1
PersonBean.ejbActivate() 1
PersonBean.ejbLoad() 1
PersonBean Constructor called 2
PersonBean.setEntityContext() 2
PersonBean.ejbActivate() 2
PersonBean.ejbLoad() 2
PersonBean Constructor called 3
PersonBean.setEntityContext() 3
PersonBean.ejbActivate() 3
PersonBean.ejbLoad() 3
PersonBean.ejbPassivate() 1
PersonBean.ejbPassivate() 2
PersonBean.ejbPassivate() 3
now for every getXXX-Methods the following occurs:
PersonBean.ejbActivate() 3
PersonBean.ejbLoad() 3
PersonBean.ejbPassivate() 3
I user OC4J 9.0.2 Production with Oracle 8.1.6.
How can I turn on Entity-Bean Caching?
Thanks,
Gilbert

Hi Gilbert,
Someone recently asked a similar question to yours. Perhaps that thread will
be helpful to you?
Author: Valeri Kireitchik
Subject: how to set exclusive-write-access="true"
Date: May 17, 2002 10:18 PT
URL:
Re: Get the Table name by providing the Sequence name
The same person (Valeri) also asked his question on two other forums:
http://www.elephantwalker.com/rfa?id=549
http://www.mail-archive.com/orion-interest%40orionserver.com/msg19037.html
Good Luck,
Avi.

Re: junit test for entity beans ... ejb 3.0

I'm confused. I'm trying to test my entity bean.
I have:
- an entity bean
- a stateless session bean for accessing the entity bean (facade)
- an interface for accessing the the stateless bean
And I'm trying to write a JUnit test class to test this bean. However, I am uncertain as to how to test this (I'm new to EJB 3.0, JBoss and Eclipse).
What would the JUnit test look like? I'm confused as to whether or not I should be injecting the interface/bean/what???
I've tried several variations. I either get "NameNotFound" - not bound exceptions or Null pointer exceptions.
What would the @EJB syntax look like or how would I do it through the context?
For Example:
@EJB private TestFacade myTest; //interface to stateless bean ?
OR
InitialContext ctx = new InitialContext();
TestResultFacadeBean myTest = (TestResultFacadeBean) ctx.lookup("localTest");
I'm confused at to which method I should be using and what object I should be accessing. If I could get either one to work, I'd be happy. :)
How do I ensure my bean is deployed to the container? What do I need to do?
If anyone has a simple example or explanation as to which method I should use and how to use it, I'd be very grateful.
Thanks very much,
LisaD

OK, you need to have several layers of testing.
Layer 0. Test the entity beans are deployable (more on this later). Basically, you need to know that all your annotations work. Things to watch out for are multiple @Id fields in one class or @EmbeddedID or @IdClass in conjuction with @ManyToOne, @ManyToMany, @OneToMany, @OneToOne and fun with @JoinTable, @JoinColumn and @JoinColumns. Once you know how these are supposed to work with the spec, it's not too bad to write it correctly each time. But there are some gotchas that will break things later on.
Layer 1. Do the functions in the classes that don't depend on annotations work as expected. Typically, this is just going to be the getters and setters in your entity classes. Of course JUnit best practice says we don't bother testing functions that look like:
public T getX() {
return this.x;
or
public void setX(T x) {
this.x = x;
as there is nothing that can go wrong with them. So in that case, your level 1 tests will just be initial values specified from constructors and verifying that the non-get/set pairs work, and that the getters you have tagged @Transient work (because you've likely put some logic in them)
Layer 2. Test the session bean methods that don't require injection to work.
Layer 3. Test the session bean methods that require injection (Mock Objects). Simulate the injection for yourself, injecting Mock Objects for the entity manager. Then you can confirm that the correct methods are being called in the correct sequences, etc.
[Note this may require some skill in designing the mock. I'm working on developing my own entitymanager mock, and if it looks usefull I'll release it to the world.
Layer 4. Test the session bean methods that require injection (Real entity manager) (See Layer 0)
For this you will need an out of container persistence implementation. Currently Hibernate and Glassfish provide beta versions. You will need a different persistence.xml file that lists all the entities. You will have to use reflection to inject the entity manager(s) that you create from an entity manager factory unless you provide a constructor that takes an EntityManager as a parameter. You may need to use reflection to call any @PostConstruct method if you made it private.
Layer 5. Navigate the relationships in the objects returned from Layer 4 using a database that has been loaded with test data.
I am currently using Layers 0, 1, 2 & 4 to test my session beans and entity beans.

Entity beans(EJB 3.0) replication in IAS 10.1.3

Hi,
I have a application with webservices, having a few stateless session beans and a few entity beans. The application has to be deployed in a grid environment, on 2 machines.
My problem is that a change in an entity needs to be replicated on both machines. Right now, with the application deployed on 2 machines, in a load balanced non-cluster environment, I have stale data. I have reviewed the option of cache coordination, but the toplink essentials don't have this feature.
As a temp solution, one of the machines was stopped. Another option is to disable the entity beans cache completely, but that's not what I'm looking for.
I have done some digging in the documentation, and it's clear that stateful beans can be replicated in a clustered environment. In this configuration, are the entity beans replicated too?

Thanks for your reply. I'm actually interested in the entities, not the web session. I need to make sure that the entities cache stays synchronized between the nodes.
Example:
I have entity "customer" for example.. I do an update from one of the nodes, changing the customer name, and do commit. This happens in node 1. I want to make sure that the node 2 knows this happened.

Are EJB ( entity beans) are cached ?

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