Beginner entity EJB question.

Hi,
I am researching into whether to use JDO for my application.
I have read that polymorphism, inheritance and complex relations are absent from EJB's. Is this true? I am thinking that maybe the place where I have read this are biased towards JDO, which is why they have stated this, and would like to get a neutral opinion.
Also, I read at JDOCentral that The acceptance of the Java Community Process� (JCP) JSR 243, also known as JDO 2.0, is in jeopardy. The recent vote by the JCP Executive Committee in the so called Public Review Ballot resulted in 5 YES votes and 10 NO votes and 1 abstention. I am a little confused. I keep hearing that JDO is so good, if that is the case, why was it rejected?
You see, I am going to use it for my project, cos I read so many good things about it, but am now unsure of whether to use it, cos if it was really that good, there would not have been 10 votes against.
Any advice would be appreciated.
Thanks.

I am researching into whether to use JDO for my
application.Good to see the sensei reseaching :)
I have read that polymorphism, inheritance and
complex relations are absent from EJB's. Is this
true? I am thinking that maybe the place where I have
read this are biased towards JDO, which is why they
have stated this, and would like to get a neutral
opinion.There are many threads on the forum as well as on http://theserverside.com on the same.
Also, I read at JDOCentral that The acceptance of
the Java Community Process� (JCP) JSR 243, also known
as JDO 2.0, is in jeopardy. The recent vote by the
JCP Executive Committee in the so called Public
Review Ballot resulted in 5 YES votes and 10 NO votes
and 1 abstention. I am a little confused. I keep
hearing that JDO is so good, if that is the case, why
was it rejected?Might have something to do with EJB 3.0
http://blog.hibernate.org/cgi-bin/blosxom.cgi/2004/05/07#ejb3
This blog discusses about the problem with JDO specs.
You see, I am going to use it for my project, cos I
read so many good things about it, but am now unsure
of whether to use it, cos if it was really that good,
there would not have been 10 votes against.This should really prevent you from using it! If JDo fits your design, you might still use it. But consider taking a look at Hibernate!
Cheers!
***Annie***

Similar Messages

Beginner's EJB Question

I've been going through the J2EE tutorial and generally understand how it works but I have a question about application clients. I get the general concept that a client uses JNDI to look up the environment entry to find an EJB. However, I think my question is "how does the JNDI entry get set in the application client's machine?" In a web client it makes sense to me because the JSP hits the server (and the server is where the JNDI entry is). On the application client the only way I can think that the entry gets there is through maybe a jar file created when the application is compiled on the app server. My guess is that that's packaged with the application client and each user who installs the application client has to put the jar in their classpath. Is that correct?
In a very much related question, I'm also wondering how the client calls methods on the enterprise beans. I assume that the jar files have some code in them that make a network connection to the app server. I just wanted to verify that my understanding of how this all works is correct.

I've been going through the J2EE tutorial and
generally understand how it works but I have a
question about application clients. I get the
general concept that a client uses JNDI to look up
the environment entry to find an EJB. However, I
think my question is "how does the JNDI entry get set
in the application client's machine?" In a web
client it makes sense to me because the JSP hits the
server (and the server is where the JNDI entry is).
On the application client the only way I can think
k that the entry gets there is through maybe a jar
file created when the application is compiled on the
app server. My guess is that that's packaged with
the application client and each user who installs the
application client has to put the jar in their
classpath. Is that correct?
Not really. JNDI binding exists on server only. When client does a lookup it connects to server's naming service (via remote call) and asks an object with specific JNDI name.
In a very much related question, I'm also wondering
how the client calls methods on the enterprise beans.
I assume that the jar files have some code in them
m that make a network connection to the app server.
I just wanted to verify that my understanding of how
w this all works is correct.
Yes, it's correct. Code that makes a network connection is called a stub (or client stub). For some app. servers (SUN AS) you need to generate stubs of EJB's and put them into clien't classpath. For others (JBoss) it's not required, because a stub can be downloaded from server.

Entity EJB Relationships Architectural Question

I need to create a hierarchy of simple objects. I will call my object
"Part" for simplicity. I have two Oracle tables to maintain my Part
hierarchy. The first table contains the detail for the part: number and
name. The second table maintains the relationship: parent_number and
child_number. I built Entity EJBs with CMP for both tables, but I don't
know if that is the "best practices" approach. If it is, how do I define
the relationships (EJB 2.0)? If it is not, how would you build it?
Thanks for helping me out,
Thomas A. Valletta

Thanks Slava,
You deserve more than a free trip to a conference for the time and effort
that you put into this board. I think you should be able to write this off
as a charitable contribution on your taxes. If you need someone to sign the
receipt, just let me know.
Anyway, back to my hierarchy issue(s). I found some information that
weblogic will set-up this kind of many-to-many relationship for you if you
set it up correctly in the weblogic-cmp-rdbms-jar.xml and the ejb-jar.xml.
So I went through the DTDs, but despite the examples the help is extremely
vague. Has anyone done this? Could anyone recommend where I could find
something more on the topic (books, magazine articles, online documentation,
code, etc)?
Thanks again,
Thomas A. Valletta
"Slava Imeshev" <[email protected]> wrote in message
news:3ec552f9$[email protected]..
Hi Thomas,
"Thomas A. Valletta" <[email protected]> wrote in message
news:[email protected]..
I need to create a hierarchy of simple objects. I will call my object
"Part" for simplicity. I have two Oracle tables to maintain my Part
hierarchy. The first table contains the detail for the part: number and
name. The second table maintains the relationship: parent_number and
child_number. I built Entity EJBs with CMP for both tables, but I don't
know if that is the "best practices" approach. If it is, how do I
define
the relationships (EJB 2.0)? If it is not, how would you build it?The best approach is the one that works for you. If the
combination of two beans works, leave it as is and
go ahead with next tasks.
Regards,
Slava Imeshev

Oracle Dabase Schema with OC4J CMP Entity EJB

I have tables in a schema called vsxlib. My Entity EJBs that map to SQL SERVER tables (no schema) work perfectly. My Entity CMP EJBs that connect need to connect to the vsxlib schema only partially work.
The findAll method works. When I add a where clause, I get no results back.
When I try a findByPrimaryKey, I get a ObjectNotFoundException.
Does OC4J version 9.0.3 support database schemas? There were examples posted at http://otn.oracle.com/sample_code/tech/java/j2ee/javacookbook/transactionsample/readme.html#descfiles say that they have an Entity bean working within a db schema.
Could it be permission related????
I even tried creating a synonym pointing to the table within the vsxlib schema.. No Luck.
I had this same problem with JBoss3.2 and found out that they did not support db schemas. That is why I was wanting to switch to OC4J because I thought for sure, being an oracle product that it would support db schemas.
Any help is greatly appreciated.

Hi Alex,
I think you may be misunderstanding the meaning of 'database schemas'. For your information, in the Oracle database, a schema is the same as a database user. For example all the database tables belonging to user SCOTT (TIGER) are said to be in the SCOTT schema.
OC4J uses the term 'database schema' differently. Here it refers to the mapping of database datatypes to java classes. Look at the "j2ee/home/config/database-schemas" subdirectoryof the OC4J installation for more details. The "data-sources.xml" file has a 'schema' tag (not sure if that's the correct name) which points OC4J to the datatype mapping XML file -- usually one of those that come with the distribution. However, I use OC4J stand-alone version and I don't need to worry about the mappings at all -- OC4J already knows the mappings for an Oracle database (I assume).
In order to access a particular Oracle schema, I merely have to log in to the database as the appropriate user. So, using the previous example, if I configure the "data-sources.xml" file to use 'scott' as the database login, then OC4J can access the SCOTT schema. You can find more details about Oracle's use of the term 'schema' in the Oracle documentation, which is available from:
http://tahiti.oracle.com
Hope this has answered your question.
Good Luck,
Avi.

How to set the isolation level on Entity EJBs

I am using 10.1.3.3 of the OC4J app server.
I am creating an application that uses EJB 2.1.
I am trying to set the isolation levels on the EJBs to either serializable or repeatable read.
When i deploy the EAR file from the OC4J admin console, i can set the isolation level property on the EJB's however when i inspect the orion-ejb-jar.xml file I do not see the isolation level being set. Furthermore, i tried to manually change the isolation setting by editing the orion-ejb-jar.xml and adding the isolation="serialiable" attribute on the entity bean descriptor. I then stopped and restarted the server. I noticed that my change was no longer in the file.
Can someone please let me know how to solve this problem and set the isolation level on Entity EJBs . Thanks

I find it at ejb.pdf from BEA.
          The transaction-isolation stanza can contain the elements shown here:
          <transaction-isolation>
          <isolation-level>Serializable</isolation-level>
          <method>
          <description>...</description>
          <ejb-name>...</ejb-name>
          <method-intf>...</method-intf>
          <method-name>...</method-name>
          <method-params>...</method-params>
          </method>
          </transaction-isolation>
          "Hyun Min" <[email protected]> wrote in message
          news:3c4e7a83$[email protected]..
          > Hi!
          >
          > I have a question.
          > How to set the transaction isolation level using CMT in descriptor?
          >
          > The Isolation level not supported in CMT?
          >
          > Thanks.
          > Hyun Min
          >
          >

Why BC4J if Entity EJB is available

Hi,
I've been working on learning the BC4J framework for the last couple of weeks and initially I was very pleasently surprised - it really looked like this was the way forward. BUT - now that I've matured past the 'trivial applications make me happy' stage, I feel like I've hit a brick wall - something as simple as adding a (row - or should I say object) method and actually getting it called from a client application seems to involve hours browsing the 'not so helpful' documentation, and it still does not work. So now I'm forced to rethink this approach and the recent annoucement of EJB 1.1 support in 8.1.7 made me pose the question:
What is BC4J except an attempt to patch up the missing entity bean support ? So far I've come up short and I would like to ask if there are others who think the same (or not - I'm just trying to get the picture so to speak :-)).
It will also be quite simpel to program the buisness classes in Java, class test them and then deploy - generating the home and remote interfaces automatically. So I fail to see what BC4J gives me that I do not get by going the entity EJB route.
What do you guys think - am I just rambling ?
br
Jacob

For general advice see Troubleshooting issues with iTunes for Windows updates.
The steps in the second box are a guide to removing everything related to iTunes and then rebuilding it which is often a good starting point unless the symptoms indicate a more specific approach. Review the other boxes and the list of support documents further down page in case one of them applies.
Your library should be unaffected by these steps but there is backup and recovery advice elsewhere in the user tip.
If you've already tried a complete uninstall and reinstall try opening iTunes in safe mode (hold down CTRL+SHIFT) as you start iTunes, then going to Edit > Preferences > Store and turning off Show iTunes in the Cloud purchases. You may find iTunes will now start normally.
tt2

Clustering read-only bean-managed entity ejbs

          I'm designing a data caching approach that relies on using read-only entity ejbs with bean-managed persistence. My design is based on the fact that WebLogic blocks on entity bean access by concurrent users for a given bean instance (unique primary key). I would like to keep only one entity bean instance active(timeoutSetting=0) for eacy primary key for all users to share. That way I only have to hit the database one time to initially populate data in the entity bean. I'm worried about this approach in a WebLogic clustered environment. From reading notes in this newsgroup and other doc, it appears that WebLogic might not use one instance of the entity bean (based upon unique primary key) in a clustered environment. Is that true (that being multiple users could get their own instance of the entity bean with the same primary key)?
          Thanks,
          Bryan


Typically, the read-write EJBs are on each WL server instance, so there is
          no remote invocation -- it is all done by reference.
          Cameron Purdy
          Tangosol, Inc.
          http://www.tangosol.com
          +1.617.623.5782
          WebLogic Consulting Available
          "Bryan Dixon" <[email protected]> wrote in message
          news:[email protected]...
          >
          > I guess I'm confused about read-write (not read-only) entity beans being
          pinned or not. This is from WebLogic 5.1 EJB doc:
          > "read-write entity EJBs do not use a clustered EJBObject stub; a client's
          method calls to a particular EJB always go to a single WebLogic Server
          instance. If the server that a client is using fails, the client must
          re-find the entity EJB using the cluster-aware home stub."
          >
          > Doesn't that mean the entity bean instance for a primary key is pinned to
          a single WebLogic Server instance? Maybe I'm just misunderstanding
          terminology about what a "particular EJB" is - I was thinking it is an
          entity bean instance for a unique primary key.
          >
          > Thanks,
          > Bryan
          >
          >
          > "Cameron Purdy" <[email protected]> wrote:
          > >>I was thinking that read-write entity beans were pinned.
          > >
          > >Not unless you pin them. Basically, that means that the JAR/XML that
          > >contains/specifies the EJB only is on one server.
          > >
          > >> So if two separate weblogic instances in a cluster did a find on an
          entity
          > >ejb with the same primary key and then performed some business method on
          > >that entity ejb, would there really be two separate bean instances in
          each
          > >weblogic instance for the same primary key?
          > >
          > >If it is not pinned, yes.
          > >
          > >--
          > >Cameron Purdy
          > >Tangosol, Inc.
          > >http://www.tangosol.com
          > >+1.617.623.5782
          > >WebLogic Consulting Available
          > >
          > >
          > >"Bryan Dixon" <[email protected]> wrote in message
          > >news:[email protected]...
          > >>
          > >> Toa, thanks again.
          > >>
          > >> There are a couple of things I'm not clear about though. One is that I
          > >want one instance of an entity bean per primary key, not a singleton of
          the
          > >entity bean itself. How would JNDI in a clustered environment help me
          > >there?
          > >>
          > >> The other question I have is about having multiple instances of an
          entity
          > >bean for the same primary key in the cluster. I was thinking that
          > >read-write entity beans were pinned. So if two separate weblogic
          instances
          > >in a cluster did a find on an entity ejb with the same primary key and
          then
          > >performed some business method on that entity ejb, would there really be
          two
          > >separate bean instances in each weblogic instance for the same primary
          key?
          > >>
          > >> Thanks again,
          > >> Bryan
          > >>
          > >> "Tao Zhang" <[email protected]> wrote:
          > >> >
          > >> >"Bryan Dixon" <[email protected]> wrote:
          > >> >>
          > >> >>The reason I was wanting one instance per primary key is that I want
          to
          > >use this entity bean to cache some data from database tables. This data
          > >doesn't change frequently, so we were wanting to get it from this entity
          > >bean's memory instead of constantly hitting the database. This data is
          > >global to all users, so we don't want to store it in stateful session
          beans.
          > >> >>
          > >> >>After reading more about the read-only cache-strategy it doesn't
          appear
          > >that any sycnhronization will occur if the entity bean for a given
          primary
          > >key is updated (state data is updated) in one weblogic instance, that
          change
          > >will not get synced up with other weblogic instances for that same
          primary
          > >key. Is that correct?
          > >> >>
          > >> >It's correct. If you do want to have exact one copy in the cluster.
          You
          > >can read Using JNDI in cluster environment.
          > >> >
          > >> >>If I deploy this entity bean with read-write cache-strategy the
          WebLogic
          > >doc reads as if I will get one instance per primary key that is pinned to
          > >one WebLogic instance and I won't get any fail-over or load-balancing on
          the
          > >ejbObject (the entity bean instance). Did I read this correctly? If
          that
          > >is the case, what is the advantage of setting up read-write entity beans
          to
          > >be clusterable - just the Home objects? I definitely could be
          > >misunderstanding something in the doc since I'm very new to clustering.
          > >> "Tao
          > >> >Zhang"
          > >> ><[email protected]> wrote:
          > >> >>>
          > >> >
          > >> >It's not only instance in the cluster. Probably many instances.
          > >> >
          > >> >If you use 2 tier clustering, failover will not happen because of
          > >co-location. But if you use 3 tier cluster, you can write the special
          code
          > >in the client side to do failover and load-balance.
          > >> >
          > >> >In a 2 tier cluster, actually the ejb load balancing and failover is
          > >almost useless.
          > >> >
          > >> >But in 3 tier, you can use it.
          > >> >
          > >> >Hope this help.
          > >> >
          > >> >
          > >> >
          > >> >>>"Bryan Dixon" <[email protected]> wrote:
          > >> >>>>
          > >> >>>>Thanks Tao.
          > >> >>>>
          > >> >>>>A couple more questions...
          > >> >>>>I was planning deploying this entity bean with the read-only
          > >cache-strategy which means our transaction attribute would be
          > >TXN_NOT_SUPPORTED. Also, our db isolation is TRANSACTION_READ_COMMITTED.
          > >> >>>>
          > >> >>>>Based upon how I was planning on deploying this entity bean, would
          > >WebLogic create an instance of the bean for each primary key in each
          > >cluster? I'm just trying to figure out how many duplicate bean instances
          > >for the primary key I could have across all clusters. I was really just
          > >wanting one instance that is shared among all clients and was hoping that
          > >the clustering would provide me with fail-over if that one cluster went
          > >down.
          > >> >>>>
          > >> >>>If you use 3 tier cluster structure, it's impossible to know how
          many
          > >instances of ejb with the same primary key. Probably one instance for
          each
          > >wls instance.
          > >> >>>In wls5.1, it's impossible to host only read only entity bean
          instance
          > >in the 3-tier cluster. Because read only entity bean are clusterable in
          both
          > >home and remote interface.
          > >> >>>
          > >> >>>>Regarding making the bean a pinned service, which it sounds like I
          > >might have to do to get the results I want, how do I do that? Is that a
          > >deployment descriptor setting? Also, if I make it a pinned service, do I
          > >get any fail-over suport by clustering the bean?
          > >> >>>>
          > >> >>>For the pinned service, you can just deployed on one or several
          server
          > >instances. The per-server properties file is a good place to put the
          > >weblogic.ejb.deploy property. If only one pinned service in the cluster,
          you
          > >can't get fail over. If the that server instance fails, the home stub
          will
          > >be removed from the jndi in other server instances.
          > >> >>>
          > >> >>>Why do you must need only one instance in the cluster? Do you want
          > >exact-only-copy? You can read Using JNDI doc about its in cluster
          > >environment.
          > >> >>>
          > >> >>>
          > >> >>>
          > >> >>>
          > >> >>>>Thanks again,
          > >> >>>>Bryan
          > >> >>>>
          > >> >>>>
          > >> >>>>
          > >> >>>>"Tao Zhang" <[email protected]> wrote:
          > >> >>>>>
          > >> >>>>>
          > >> >>>>>Bryan Dixon <[email protected]> wrote in message
          > >> >>>>>news:[email protected]...
          > >> >>>>>>
          > >> >>>>>> I'm designing a data caching approach that relies on using
          > >read-only
          > >> >>>>>entity ejbs with bean-managed persistence. My design is based on
          the
          > >fact
          > >> >>>>>that WebLogic blocks on entity bean access by concurrent users for
          a
          > >given
          > >> >>>>>bean instance (unique primary key). I would like to keep only one
          > >entity
          > >> >>>>>bean instance active(timeoutSetting=0) for eacy primary key for
          all
          > >users to
          > >> >>>>>share. That way I only have to hit the database one time to
          > >initially
          > >> >>>>>populate data in the entity bean. I'm worried about this approach
          in
          > >a
          > >> >>>>>WebLogic clustered environment. From reading notes in this
          newsgroup
          > >and
          > >> >>>>>other doc, it appears that WebLogic might not use one instance of
          the
          > >entity
          > >> >>>>>bean (based upon unique primary key) in a clustered environment.
          Is
          > >that
          > >> >>>>>true (that being multiple users could get their own instance of
          the
          > >entity
          > >> >>>>>bean with the same primary key)?
          > >> >>>>>>
          > >> >>>>>
          > >> >>>>>
          > >> >>>>>It's true. In a cluster environment, each wls instance can have
          their
          > >ejb
          > >> >>>>>instance. The block of concurrent access to the ejb data is up to
          > >your
          > >> >>>>>transaction attribute and isolation level and your database.
          > >> >>>>>
          > >> >>>>>If you only want to keep one instance active, you can make the
          > >read-only
          > >> >>>>>entity bean a pinned service, to be deployed in one instance. But
          the
          > >> >>>>>network overhead is worse.
          > >> >>>>>
          > >> >>>>>
          > >> >>>>>> Thanks,
          > >> >>>>>> Bryan
          > >> >>>>>
          > >> >>>>>
          > >> >>>>
          > >> >>>
          > >> >>
          > >> >
          > >>
          > >
          > >
          >

How to use the same Entity EJB to access the same table in 2 syb databases

We are trying to convert an application to J2EE. We have the following
concern. The application requires the use of 10 sybase databases with
identical tables. One database per branch. We would like to be able to use the same set of entity EJBs to access all databases.
One solution we can think of is to use bmp entity beans and have a dispatcher session bean pass the database that the entity bean has to connect to.
Would it work?
Is there a more elegant way to do this?

I don't know if there is a more elegant way to do it, but that will work. I have a similar scenario, one database per customer. You'll have to use BMP and get your connections based on the branch.
Each one of my DAO methods requires that a customer ID be passed in for each method. The customer ID is part of the primary key for each entity bean; therefore, if I need to find a deposit (entity) for a customer, I pass the customer ID and deposit ID to my session facade, create the PK using these, do a findByPrimaryKey, etc. In the ejbLoad, I use the customer ID and the deposit ID to pass into the DAO. There, another class (ConnectionFactory) returns a proper connection based on the customer ID passed, which I use to do my queries.
Paul

Oracle sequence problem in CMP Entity EJB

I have a problem with Oracle sequence when I am using from the CMP entity EJB in WebLogic
6.1:
The problem is when the WebLogic server starts it acquires the correct sequence number
from Oracle, but during the runtime, when I open a new sqlplus window and increment
the sequence number, the container is not picking up from the new incremented value
instead it is still continuining by incrementing the old sequence number it has acquired
when it fetched from Oracle last time.
The sequence increment and key-cache-size in weblogic-cmp-rdbms-jar.xml are exactly
same
Any help would be greatly appreciated.

Change the key-cache-size to 1 in weblogic-cmp-rdbms-jar.xml and then try
your experiment again.
-- Anand
"Satya" <[email protected]> wrote in message
news:3d06274c$[email protected]..
>
I have a problem with Oracle sequence when I am using from the CMP entityEJB in WebLogic
6.1:
The problem is when the WebLogic server starts it acquires the correctsequence number
from Oracle, but during the runtime, when I open a new sqlplus window andincrement
the sequence number, the container is not picking up from the newincremented value
instead it is still continuining by incrementing the old sequence numberit has acquired
when it fetched from Oracle last time.
The sequence increment and key-cache-size in weblogic-cmp-rdbms-jar.xmlare exactly
same
Any help would be greatly appreciated.

Database Views with Entity EJBs

Is it possible to use Weblogic Workshop to create a CMP entity EJB on an Oracle database view for a Weblogic 8.1 server?
Is there special configuration I need to do for either the Oracle or Weblogic side to accomplish this?
Thanks.
Tania

I can manually create the EJB, an it builds just
fine, but when I go to deploy it, I get the following
error:
[EJB:011076]Unable to deploy the EJB
'AssortmentMerchandise' because the databas
e table 'K_BA01.BAV_ASRT_CLUSTR_DAT' is not
accessible. Please ensure that this
table exists and is accessible.
The view is on the same datasource that I have
successfully created all of my other entity EJBs
(from tables).
I can select data from the view using JDBC and the
same datasource that I am trying to associate the EJB
to.
Any ideas what might be wrong with my view?Are you using synonyms or aliases? I would double check those...
Log in using same username and password as weblogic and try a simple query:
select * from K_BA01.BAV_ASRT_CLUSTR_DAT

Mapping of an entity EJB to multiple database tables using CMP?

Can one entity EJB have attributes split between (mapped to) multiple databse tables?
Would CMR work properly between two such entity EJBs (both mapped to multiple database
tables).

Hi Milos.
Can one entity EJB have attributes split between (mapped to) >>multiple databasetables?
A CMP Entity should be always mapped a record in a single DB table.
Thanks.
Ji Zhang
Developer Relations Engineer
BEA Support

Bmp entity ejb transactions, using DAO objects

hi all,
i'm new to entity ejb's... i'm using the j2ee reference implementation (1.3.1) with the cloudscape db to test my code.
i can't seem to get my ejbCreate method to work. i'm using a DAO object to encapsulate all my database code, and simply call dao.insert(...) in my ejbCreate method.
i tested the dao object, and it works fine when it's invoked straight. but when i try to invoke under the ejb container i run into problems:
i deploy the bean with container managed transactions:
(1) with the 'required' attribute:
I get a javax.transaction.RollbackException nested inside another RollbackException, nested inside a RemoteException, nested inside another RemoteException. The final RollbackException says <<no stack trace available>>...
So I've got no clue what's causing it...
(2) with the 'never' attribute:
I get a NullPointerException nested inside another NullPointerException, nested inside a RemoteException, nested inside another RemoteException. The final NullPointerException says <<no stack trace available>>...
So I've got no clue what's causing it...
I'm assuming something messed up with my deployment -- but I've checked it against all the examples I can find -- seems to be correct. Would the encapsulated Data Access code cause a problem? Some other config problem?
Thanks in advance for any help!!

i'm using the cloudscape db that's already configured with the server. i believe the datasource is correctly configured, as i am able to successfully invoke the dao methods straight -- the problem occurs when I try to do it via the entity bean that uses the dao object.
here's my server startup messages:
Binding DataSource, name = jdbc/Cloudscape, url = jdbc:cloudscape:rmi:CloudscapeDB;create=
true
Binding DataSource, name = jdbc/DB1, url = jdbc:cloudscape:rmi:CloudscapeDB;create=true
Binding DataSource, name = jdbc/EstoreDB, url = jdbc:cloudscape:rmi:CloudscapeDB;create=tr
ue
Binding DataSource, name = jdbc/InventoryDB, url = jdbc:cloudscape:rmi:CloudscapeDB;create
=true
Binding DataSource, name = jdbc/DB2, url = jdbc:cloudscape:rmi:CloudscapeDB;create=true
Binding DataSource, name = jdbc/XACloudscape, url = jdbc/XACloudscape__xa
Binding DataSource, name = jdbc/XACloudscape__xa, dataSource = COM.cloudscape.core.RemoteX

Deployment error: The Entity EJB requires the table: to be accessible

Hello
When I deploy my EJBs, WEBLogic throws an exception:
Unable to deploy EJB: OrderBean from ejb-jar-ic.jar:
The Entity EJB requires the table: Order to be accessible. Please ensure that th
is table exists and is accessible.
I use built in Cloudscape database.
And I have those lines in descriptor:
<weblogic-rdbms-bean>
<ejb-name>OrderBean</ejb-name>
<data-source-name>ejbDS</data-source-name>
<table-name>Order</table-name>
<field-map>
<cmp-field>totalAmount</cmp-field>
<dbms-column>totalAmount</dbms-column>
</field-map>
<field-map>
<cmp-field>time</cmp-field>
<dbms-column>ordertime</dbms-column>
</field-map>
<field-map>
<cmp-field>orderID</cmp-field>
<dbms-column>orderID</dbms-column>
</field-map>
</weblogic-rdbms-bean>
<create-default-dbms-tables>True</create-default-dbms-tables>
thanx in advance
Maris

Hi Maris,
I see that you have create-default-dbms-tables set to true so WLS should be creating
the database table for your EJB. If you can give me some more information, I'll be
able to help you further. What version of WLS + service pack are you using? Also,
is this a 1.1 bean or 2.0? Lastly, what are the types of the CMP fields in your
bean?
As a work-around, you can try creating the database table yourself before deploying
the bean. This should resolve the deployment problem.
- Matt
Maris wrote:
Hello
When I deploy my EJBs, WEBLogic throws an exception:
Unable to deploy EJB: OrderBean from ejb-jar-ic.jar:
The Entity EJB requires the table: Order to be accessible. Please ensure that th
is table exists and is accessible.
I use built in Cloudscape database.
And I have those lines in descriptor:
<weblogic-rdbms-bean>
<ejb-name>OrderBean</ejb-name>
<data-source-name>ejbDS</data-source-name>
<table-name>Order</table-name>
<field-map>
<cmp-field>totalAmount</cmp-field>
<dbms-column>totalAmount</dbms-column>
</field-map>
<field-map>
<cmp-field>time</cmp-field>
<dbms-column>ordertime</dbms-column>
</field-map>
<field-map>
<cmp-field>orderID</cmp-field>
<dbms-column>orderID</dbms-column>
</field-map>
</weblogic-rdbms-bean>
<create-default-dbms-tables>True</create-default-dbms-tables>
thanx in advance
Maris

Deploying CMP Entity EJB: NullPointerException

Hi,
I have built a very simple CMP Entity EJB, when deploying it to Oracle8i 8.1.7, it fails and return this error:
Processing container managed persistence bean...java.lang.NullPointerException
java.lang.Class java.lang.Class.forName0(java.lang.String, boolean, java.lang.ClassLoader)
java.lang.Class java.lang.Class.forName(java.lang.String)
void oracle.aurora.ejb.deployment.GenerateEjb.cmpDeploy(oracle.aurora.ejb.dd.OracleEntityDescriptor)
void oracle.aurora.ejb.deployment.GenerateEjb.invoke()
void oracle.aurora.server.tools.sess_iiop.ToolImpl.invoke(java.lang.String[], java.io.InputStream, java.io.PrintStream, java.io.PrintStream)
void oracle.aurora.ejb.deployment.GenerateEjb.main(java.lang.String[])
Can anyone help????
Patrick.
null

I have the same problem with JDeveloper 3.2.3 and 8.1.7.2
Here is the error:
*** Executing deployment profile E:\Xaris\JDeveloper\General\EJBs\EmpCmp\EmpCmp.prf ***
*** Generating archive file E:\Xaris\JDeveloper\General\EJBs\EmpCmp\empcmp.jar ***
Compiling the project...done
Validating the profile...done
Initializing deployment...done
Scanning project files...done
Generating classpath dependencies...done
Generating archive entries table...done
*** Archive generation completed ***
*** Deploying the EJB to 8i JVM ***
EJB deployment argument list:
"E:\Program Files\Oracle\JDeveloper 3.2.3\java1.2\jre\bin\javaw"
"-DPATH=E:\Program Files\Oracle\JDeveloper 3.2.3\bin;E:\Program Files\Oracle\JDeveloper 3.2.3\java1.2\bin"
-classpath
"E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\aurora_client.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\lib\javax-ssl-1_2.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\jasper.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\vbjorb.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\vbjapp.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\vbjtools.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\vbj30ssl.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\aurora.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\sqlj\lib\translator.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\sqlj\lib\runtime.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\aurora\lib\mts.jar;E:\Xaris\JDeveloper\General\EJBs\EmpCmp\classes;E:\Program Files\Oracle\JDeveloper 3.2.3\lib\jdev-rt.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\jdbc\lib\oracle8.1.7\classes12.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\lib\connectionmanager.zip;E:\Program Files\Oracle\JDeveloper 3.2.3\lib\javax_ejb.zip;C:\Program Fil
s\JavaSoft\JRE\1.3.1\lib\i18n.jar;C:\Program Files\JavaSoft\JRE\1.3.1\lib\jaws.jar;C:\Program Files\JavaSoft\JRE\1.3.1\lib\rt.jar;C:\Program Files\JavaSoft\JRE\1.3.1\lib\sunrsasign.jar;E:\Program Files\Oracle\JDeveloper 3.2.3\lib\xmlparserv2.jar"
oracle.aurora.ejb.deployment.GenerateEjb
-u
harris
-p
harris
-s
sess_iiop://192.168.10.218:2481:WORK
-republish
-keep
-temp
TEMP
-descriptor
"E:\Xaris\JDeveloper\General\EJBs\EmpCmp\EmpCmp.xml"
-oracledescriptor
E:\Xaris\JDeveloper\General\EJBs\EmpCmp\EmpCmp_oracle.xml
-generated
"E:\Xaris\JDeveloper\General\EJBs\EmpCmp\EmpCmpClient.jar"
"E:\Xaris\JDeveloper\General\EJBs\EmpCmp\empcmp.jar"
Reading Deployment Descriptor...done
Verifying Deployment Descriptor...done
Gathering users...done
Processing container managed persistence bean...java.lang.NullPointerException
     java.lang.Class java.lang.Class.forName0(java.lang.String, boolean, java.lang.ClassLoader)
     java.lang.Class java.lang.Class.forName(java.lang.String)
     void oracle.aurora.ejb.deployment.GenerateEjb.cmpDeploy(oracle.aurora.ejb.dd.OracleEntityDescriptor)
     void oracle.aurora.ejb.deployment.GenerateEjb.invoke()
     void oracle.aurora.server.tools.sess_iiop.ToolImpl.invoke(java.lang.String[], java.io.InputStream, java.io.PrintStream, java.io.PrintStream)
     void oracle.aurora.ejb.deployment.GenerateEjb.main(java.lang.String[])
null
*** Errors occurred while deploying the EJB to 8i JVM ***
*** Deployment completed ***
Does anyone know what is the problem?

Session EJB vs ENtity EJB

Why/When would you use Session EJB instead of Entity EJB to access Database values

You might use a Session Bean to access the database when you didn't want the overhead of Entity Beans or if the data you were retrieving didn't relate to the entity structure easily.
Have a look at the Fast Lane Reader pattern in the J2EE Design Patterns section to get more information about an example. Here the data is only being read and presented to the user so support for updating the values, security and concurrency isn't needed and is purely overhead.
Hope this helps.

Beginner entity EJB question.

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