BMP (Bean Managed) vs CMP (Contained Managed) Beans

Hi,
Actually this is more of a clarification question than an actual issue. To give a background, we're creating a Web Dynpro application that must be connected to an Oracle Database. However,we're in the process of deciding whether to use BMP or CMP to connect the application to the database.
However, there is a direction to use Oracle Views and Stored Procedures. Since I am new to CMP, I was wondering if this is possible in CMP beans as well.
Would like to ask if you have any suggestions on which is the better approach? Pros and cons would be helpful, and additional resources would be useful too.
Thanks!
Angelo

You are probably trapping the exception, so the container never see's it.

Similar Messages

Bean-Managed vs. Container-Managed Persistence

Hello,
I would like the real world skinny on bean-managed persistence vs. container-managed persistence. I have heard the bean-managed offers higher scalability and performance, while container-managed offers simplicity but with a cost. Can someone give me some perspective?
Thanks,
Rob Miller

Wrong forum, but I guess if you are new to java it could be argued that anything goes...
General rule:
use CMP if you don't have worries about speed or legacy systems.
use BMP if you need to control the persistence and/or want to connect to legacy host systems. BMP allows you to set up caching and transaction handlers to handle the presistence in a manner more suited to your needs.

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

Container Managed Persistence entity bean relationship fields

I want to ask something that until now still confuse. Did Relationship fields in Container Managed Persistence entity beans declare , inside Database table or only Persistence fields .
If Relationship fields not declare inside database table ,how if SQL calls the relationship fields between related entity bean.
did container handle this task.
example: I have 2 entity bean with CMP(Container Managed Persistence)version 2.0
call Player and Team. every entity bean have own relationship fields and persistence fields.
player has playerId(primary key),name,position,age persistence fields and teams is relationship fields.
team has teamId(primary key),name,city and players is relationship fields.
I know that all persistence fields is declare in own database table but how about relationship fields.
can you tellme, How SQL calls can access relationship fields if relatiosnship fields is not declare in database table.
I use J2EE RI SDK version 1.3
and deploytool .
thank's .

thank's for your reply .Now I have another problem
I use J2EE RI from java.sun .I try to follow example in j2eetutorial about CMP Example call RosterApp.ear .
I dont'change anything code inside RosterApp.ear but when I deploy and runclient command thereis syntax error :
java.rmi.ServerException: Remote exception occured in server thread :nested exception is java.rmi.ServerException :exception thrown from bean :nested exception is : java.ejb.EJBException :nested exception is :java.sql.SQLException :syntax error or access violation ,message from server: "you have an error in SQL syntax near "
"leagueBeanTable" WHERE "leagueId" = 'L1' at line 1
in example ,RosterApp.ear use Cloudscape database ,but I try to use Mysql database for RosterApp.ear ,is there any different syntax SQL from Cloudscape to Mysql .
if like that ,so I must edit first SQL calls from Cloudscape to MYSQL . I think because relationship fields is for entity beans only ,so how if mysql database want to access foreign key another table because foreign key isn't declare in databse table.
example : I have 3 entity bean call player, team, league .
1. PlayerEJB have persistence fields name, position, playerId(primary key), cmr fields is teams
2. TeamEJB have persistence fields name, city, teamId (primary key) , cmr fields is players and leagues .
3. LeagueEJB have persistence fields name ,sport, leagueId(primary key), cmr fields is teams
so table is
PlayerEJB <--->TeamEJB<--->LeagueEJB
Player have some finder method call findBySport(String Sport) .
because Sport is persistence fields for LeagueEJB
so PlayerEJB must traverse TeamEJB first before LeagueEJB
EJB QL : SELECT distinct object(p) FROM Player (p) IN (p.teams) AS t
WHERE t.league.sport = ?1
I know that Container will translates EJB QL to SQL calls ,but default is only for cloudscape database and I use for MYsql .
so can you helpme how to query method findBySport(String sport) to Mysql calls .
thereis no foreign key between table in database table there is only Relationship fields in entity bean.

How to add a finder method in the container manager Bean in the weblogic6.1

in the environment jbuilder6 andweblogic6.1,use container manager entity Bean,it can automatic generate the findAll() method,I want to add a new method to find an element in the home interface,such as findByName(),name is a element of a table of the database.in the weblogic-cmp-rdbms-jar.xml,this is part of the fiile:
<finder>
<finder-name>findAll</finder-name>
<finder-query><![CDATA[ (= 1 1) ]]></finder-query>
</finder>
<finder>
<finder-name>findByName</finder-name>
<finder-param>java.lang.String</finder-param>
<finder-query><![CDATA[ (=name $name) ]]></finder-query>
</finder>
It can successfully compile the findAll(),but it is wrong when compile the findByName(),as follows
"www.ejbgrpx": Method Name: findByName
"www.ejbgrpx": Invalid specifications for a WebLogic RDBMS CMP EJB.
"www.ejbgrpx": ERROR: Error from ejbc: weblogic.ejb20.cmp11.rdbms.finders.IllegalExpressionException:
"www.ejbgrpx": While trying to process Finder
"www.ejbgrpx": Parameter Types: (java.lang.String)
"www.ejbgrpx": WebLogic Query: (= name $name)
"www.ejbgrpx": Finder Expressions: ()
"www.ejbgrpx": Could not parse WLQL expression: (= name $name) null
"www.ejbgrpx": ERROR: ejbc found errors
thank you

The finder methods that you are referring to are only simple finder methods. If you would like to add specialized finder methods, you can make your entity bean with bean managed persistence and not container managed. If you are using EJB 2.0, your entity bean with container managed persistence can use EJB QL for finder methods. You can search for this topic and/or download the EJB 2.0 specifications
Hope this helps

Finder method in container-managed entity bean

Finder method of a container entity bean is taking the primary key class object of another entity bean. How to map this in the xml descriptor file weblogic-cmp-rdbms.xml for this type of beans.
I am trying to deploy the jasmine computer store of Mastering EJB by EdRoman.
I couldn't write the deployment file weblogic-cmp-rdbms.xml for Order Entity bean which uses CustomerPK as an argument in its finder method.
Please tell me how to write this. I am trying on weblogic 5.1
Thanx in advance
Srivatsa

hello,
in container managed persistence, you specify on your xml file the name of your table. so the primary key you want to use have to be a foreign key in your table. otherwise i don't think that you can use a container managed persistence.
Najib.

Container Managed Entity Beans and Client Identifier in Oracle

Is it possible to use Container Managed Entity Beans (EJB with CMP)
in a way that the Oracle database sessions still know the
individual Client Identifiers of the actual users
(not just the Identifier of the proxy user defined in the
Connection Pool)?
If Yes: How?
If No: The consequence would be that the
technologies EJB with CMP cannot be user together with
Oracle Virtual Private Databases (VPN) because VPN requires
some kind of Client Identifier.
I am grateful for any hint.
Regards,
Martin Siepmann
+49 (0)163 / 7765328

Not quite an auto-incrementing PK, but it is managed by the container. the following is from the turorial
Generating Primary Key Values
For some entity beans, the value of a primary key has a meaning for the business entity. For example, in an entity bean that represents a phone call to a support center, the primary key might include a time stamp that indicates when the call was received. But for other beans, the key's value is arbitrary--provided that it's unique. With container-managed persistence, these key values can be generated automatically by the EJB container. To take advantage of this feature, an entity bean must meet these requirements:
* In the deployment descriptor, the primary key class is defined as a java.lang.Object. The primary key field is not specified.
* In the home interface, the argument of the findByPrimaryKey method must be a java.lang.Object.
* In the entity bean class, the return type of the ejbCreate method must be a java.lang.Object.
In these entity beans, the primary key values are in an internal field that only the EJB container can access. You cannot associate the primary key with a persistent field or any other instance variable. However, you can fetch the bean's primary key by invoking the getPrimaryKey method, and you can locate the bean by invoking its findByPrimaryKey method.
Maybe that is good enough
christina

Container-managed / bean-managed transaction demarcation

I am trying to make sure I understand container-managed and bean-managed transaction demarcation and in particular where you have one bean calling another bean. What happens where one of the beans has container-managed transaction demarcation and the other bean-managed transaction demarcation. In fact the initial question to ask is, is this allowed?
Lets use an application scenario to illustrate the issue. The application has a payment transaction. Payments can be received in one of two ways:
1. As a payment at a branch where the individual payment is processed on a client application and resulting in the processing of a single payment transaction.
2. As a batch of payments received from a bank containing, potentially, thousands of payment transactions.
The proposed implementation for this uses two session beans. The first is a Payment session bean that implements the business logic as appropriate calling entity beans to persist the change. The second is a BatchPayment session bean. This processes the batch of payment transactions received from the bank. The BatchPayment reads through the batch of payments from a bank calling the Payment session bean for each payment transaction.
Lets look at the transactional properties of both session beans. In order to support the client application the Payment session bean can implicitly enforce transactional integrity and is therefore set to container-managed transaction demarcation. However the BatchPayment session bean will want to explicitly specify transaction demarcation for performance reasons. The transactional "commit" process is relatively expensive. When processing a large batch of transactions rather than performing a commit after every transaction is processed we want to perform the commit after a number of transactions have been processed. For example, we may decide that after every 100 transactions have been processed we commit. The processing will have a shorter elapsed time as we have not had to perform 99 commit processes. So the BatchPayment session bean will want to explicitly specify its transaction demarcation and will therefore be defined with bean-managed transaction demarcation.
How would this be implemented? A possible solution is:
Payment session bean implemented with container-managed transaction demarcation with transaction scope set to Required.
BatchPayment session bean implemented with bean-managed transaction demarcation with transaction scope set to Required.
When the client application is run it calls the Payment bean and the container-managed transaction demarcation ensures the transactional integrity of that transaction.
When a BatchPayment process is run it explicitly determines the transaction demarcation. Lets say that after every 100 Payment transactions (through 100 calls to the Payment session bean) have been processed the BatchPayment bean issues a commit. In this scenario however we have mixed container-managed and bean-managed transaction demarcation. Hence my original question. Can container-managed and bean-managed transaction demarcation be mixed? If not how is it possible to implement the requirements as described above?
Thanks for any thoughts.
Paul

BatchPayment session bean implemented with bean-managed transaction demarcation with transaction scope set to Required.Didn't quite understand this sentence.... if it's BMT it has no declarative transaction attributes such as "Required"....
Anyway, first of all I'll have to ask, Why at all would you want to commit in the middle of the business method? to get as much through as possible before a potential crash? :-)
Can container-managed and bean-managed transaction demarcation be mixed?Yes, of course. Just remember that the "direction" you are refering to ->
a BMT SB that propagates it's transaction to a method in a CMT SB that is demarcated with "Required" is the simplest case. If it were "reversed", or for that matter any BMT that might be called within an active transaction context must perform logic to manipulate the transaction state. For instance(and most common case), checking to see if a transaction is active and if so not to do anything(just use the one that is already active).
If not how is it possible to implement the requirements as described above?You could also implement this scenario with CMTs all the way through. your BatchPayment SB could consist of two methods, one (say, execute(Collection paymentsToExecute) ) with "Supports", and another(say executeBatchUnit(Collection paymentsToExecute, int beginIndex, int endIndex) ) with "RequiresNew".
then have the first just call the other with indexes denoting each time a group of payments.
Still, it does seem more suitable using BMT for these kind of things.....
Hope this helped....

About Container-managed Transactions and Bean-managed Transactions

as the document of weblogic7.0 describe the differents of Container-managed
          Transactions and Bean-managed Transactions,and in the document,It tell us
          details of using Bean-managed Transactions,such as \:
          import javax.naming.*;import javax.transaction.UserTransaction;.....
          import java.sql.*;import java.util.*;
          UserTransaction tx = (UserTransaction)
          ctx.lookup("javax.transaction.UserTransaction");tx.begin();
          tx.commit() //or tx.rollback
          but how to use Container-managed Transactions?
          what is EJB's deployment descriptor? can someone tell me?
          i wonder someone will show me an example of how to use Container-managed
          Transactions.
          thanks
          fish


Many if not all of the WLS EJB examples use container-managed
          transactions. That's a good place to start.
          I'd also recommend that you pick up a decent EJB book. There's several
          on the market right now.
          -- Rob
          fish wrote:
          > <ejb-jar>
          > <enterprise-beans>
          > <session>
          > <ejb-name>testbean</ejb-name>
          > <home>test.test.TestHome</home>
          > <remote>test.test.Test</remote>
          > <ejb-class>test.test.TestBean</ejb-class>
          > <session-type>Stateful</session-type>
          > <transaction-type>Container</transaction-type>
          > </session>
          > </enterprise-beans>
          >
          > <assembly-descriptor>
          > <container-transaction>
          > <method>
          > <ejb-name>EmployeeRecord</ejb-name>
          > <method-name>*</method-name>
          > </method>
          > <trans-attribute>Required</trans-attribute>
          > </container-transaction>
          > </assembly-descriptor>
          > </ejb-jar>
          > ----------------------------------------------
          > seems i have to write ejb-jar.xml like this,am i right?
          > what about <ejb-client-jar>? is it needed in this xml file?
          >
          > thanks
          >
          > fish
          >
          >

Bean or Container Managed Persistence

Hi,
I've been reading up on the Sun J2EE tutorial. One of the topics there is bean or container managed persistence. It states that container managed is easier for developers and allows for more portability. The class codes are much smaller compared to bean managed and developers need not worry about database queries.
Can anyone share their experiences on this? Any 'Real World' advantages and disadvantages? Is there a guideline I can follow when to use bean or container managed persistence?
Thanks,
-Ray

That seems like an obvious flaw. So why was it even considered in the
J2EE framework? I mean wouldn't the J2EE architects immediately realize
that? Just doesn't make sense to me why there's even a tutorial or books
for it. What does it suppose to solve then??I know what you mean... again, I think they thought it looked good on paper.
And it gets worse...
Before you use Entity Beans you must be absolutely sure that there will never be another app that accesses the underlying table that doesnt use the EntityBean to do it... For example a C++ App that accesses the tables directly... otherwise you have to set a flag in the App Server that states that basically every time a property on an EntityBean is read the Bean will have to RE-READ the beans state from the database!!
Some things look really good, from an OO perspective, but dont work really well in reality. Sure Entity Beans look really good in the example program in the tutorial, but what happens when you multiply the number of entity beans by 1000, 100,000, or more? Just think of the CPU, and Memory overhead for instantiating all those objects!
There are people out there who believe that using Stored Procedures is a no-no because in their minds it puts "Business Logic" on the database and not the App Server...To this I say... BUNK... Ive seen several instances where by simply moving a set of queries from the App Server to a stored procedure on the database, allowed for a 10-20 times performance gain because of the elimination of network IO. In one instance I saw a query go from 3 hours execution time on the App Server to under 10 minutes on the database... But stored procedures arent OO...
So IMHO before you use EntityBeans at all... be absolutely sure you understand all of the ins-and-outs of doing so.

Problems while defining EJB relations for container managed bean

I am having a problem while trying to create my relations for my container managed bean.
My Database schema is:
Order table
order_id
message
WorkItem table:
order_id
item_id
message
I have defined my OrderBean to have:
@LocalMethod()
@CmrField
public abstract Collection getCmWorkItemsCmr();
@LocalMethod()
public abstract void setCmWorkItemsCmr(Collection workItems);
I am not sure how to define my relation for my class:
@Relation(cmrField = "cmWorkItemsCmr", multiplicity = Relation.Multiplicity.MANY, name = "Orders-CmWorkItems")
An order can have many workitems. I am not sure how to fill in the rest for foreign Key jointable and such.
Any help pointing me in the right direction would be helpful.
Thanks,
Ian

I am having a problem while trying to create my relations for my container managed bean.
My Database schema is:
Order table
order_id
message
WorkItem table:
order_id
item_id
message
I have defined my OrderBean to have:
@LocalMethod()
@CmrField
public abstract Collection getCmWorkItemsCmr();
@LocalMethod()
public abstract void setCmWorkItemsCmr(Collection workItems);
I am not sure how to define my relation for my class:
@Relation(cmrField = "cmWorkItemsCmr", multiplicity = Relation.Multiplicity.MANY, name = "Orders-CmWorkItems")
An order can have many workitems. I am not sure how to fill in the rest for foreign Key jointable and such.
Any help pointing me in the right direction would be helpful.
Thanks,
Ian

Container-managed persistence Entity bean

WE use a container-managed persistence Entity bean. To handle the state synchronization between the object & the database, what must WE do?
Thanks in Advance

That's the container's job. You can use the commit option A/B/C to control how the DB and objects are synchronized.
-Scott
http://www.swiftradius.com

Setting composite key in Container Managed Entity Bean

In my database table i set primary key to two columns making them as composite key. how do i set that in my container managed entity bean home interface findByPrimaryKey() method and in deployment descriptor file.

1. create another class (say CompositePK) that will embed the two fields keyA and keyB corresponding to the two pk of your table (declare them public) .
2. in your Bean declare keyA and keyB public.
3. in the dd declare your bean primary-key-class as CompositePK and the primary-key-field as keyA and keyB.
this is the method i use (with BAS) even if the key is simple (such as Integer).

Container managed bean persistence queries

Hi,
I want to know where the container generated java sources and
classes for the container managed beans will be sotred as i want
to look out the sql queries that is not inserting and updating
the values into the tables.
As well i want to refer how the bean persistence is handled.
thanks
kumar

Hi,
I want to know where the container generated java sources and
classes for the container managed beans will be sotred as i want
to look out the sql queries that is not inserting and updating
the values into the tables.
As well i want to refer how the bean persistence is handled.
thanks
kumar

Can i user UserTransaction in a Container-managed transaction Bean

can i use UserTransaction to control transaction boundaries in a container-managed transaction bean method?
below is the method:
there is one-to-many between Employees and SalaryItem
@TransactionAttribute(value = TransactionAttributeType.REQUIRED)
private void initEmployeesSalary(Long salarySumId) {
for(Employees employees: liEmployees){
for (int i = 0; i < 20; i++) {
SalaryItem item = new SalaryDetailItem();
employees.addSalaryItem(item);
when there are about 1000 employees,the method run very slow.
What do you think I should do?
null

Hi again,
The EJB specs say that a stateful Session Bean with CMT is NOT allowed to use the UserTransaction; see page 361 of the EJB2.0 specification. So combining them will not (or should not) work.
I suggest CMT+SessionSynchronization combined with using a flag to indicate whether notify should be called or not. Otherwise, you could try splitting up the bean into two beans: one with CMT and another one without. The one without CMT could use the UserTransaction and notify.
Also, you might want to check http://www.onjava.com/pub/a/onjava/2001/10/02/ejb.html
Hope that helps a bit,
Guy
http://www.atomikos.com

BMP (Bean Managed) vs CMP (Contained Managed) Beans

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