Answered by Jey on 2005-05-08 11:06:46: When the EJB container needs to synchronize the instance variables of an entity bean with the corresponding values stored in a database, it invokes the ejbLoad and  ejbStore methods. The ejbLoad method refreshes the instance variables from the database, and the ejbStore method writes the variables to the database. The client cannot call ejbLoad...

Vj

• Jul 22nd, 2005

Note: ejbLoad and ejbStore methods are to be coded only if you are creating a BMP. For CMP these methods are handled by the container.

Sanjay Guha

• May 25th, 2005

ejbLoad method: This method is called when it is necessary to synchronize the bean with data from the database. This will most likely trigger a SELECT to occur. The ejbLoad is triggered when the ...

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Answer posted by Mohan on 2005-05-21 19:24:23: All Beans support Instance Pooling

Vj

• Jul 22nd, 2005

EJB does indeed support the effect of pooling stateful session beans.Only a few instances can be in memory when there are actually many clients. But this pooling effect does not come for free---the pa...

raj

• Jul 4th, 2005

Statefull session bean does not maintain instance pooling, stateless session beans and entity beans can maintain instance pooling

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Amitav C

• Jul 21st, 2005

Its actual implementation is done by the Container.

RajeshRokkam

• Jun 3rd, 2005

We have to provide abstract data to object mapping that maps the fields in our bean to a batabase, and abstract methods methods that corelate these fields.

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Ginni

• Jul 21st, 2005

Yes, you can create entity bean without impelementing the create() method. The ejbs will be instantiated by findByPK or any finder methods.

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To have a consistent interface, so that there is no different interface that you need to implement for Stateful Session Bean and Stateless Session Bean. Both Stateless and Stateful Session Bean implement javax.ejb.SessionBean and this would not be possible if stateless session bean is to remove ejbActivate and ejbPassivate from the interface. You could argue that the two (stateful and stateless) are...

Ginni

• Jul 21st, 2005

The simple reason is to manage your resources. For eg. if you use/open any third party resource on ejbActivate, you need to make sure ejbPassivate close the connection/ release the use of resource regardless of stateful session or stateless session.

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JavaPerson

• Jul 21st, 2005

Decorator is not a EJB Design pattern. It is a Java pattern.

sai

• Apr 28th, 2005

No

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Srinivas Jadcharla

• Jul 18th, 2005

Yes

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Srinivas Jadcharla

• Jul 18th, 2005

2 types of exceptions can occur    1.System Exception - We can define some error codes the in the property file and show it to the JSP  2.Application Exception.. - We can customise the exception and show the appropriate error  

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Srinivas Jadcharla

• Jul 18th, 2005

The EJB container provides services to EJB components. The services include transaction, naming, and persistence support.    Transaction support An EJB container must support transactions. E...

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KishoreDVS

• Jul 12th, 2005

we can use when we want to forward a page with in the context. using sendRedirect() method we can forward to jsp which is in another context also. And in there will be only one request procesed betw...

sunil

• Jul 6th, 2005

Sendredirect will happen on clint side & request , rsponse will be newly created, for forward action it is server side action & request, response is passed & not modified or destroyed.

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Answer posted by Mohan on 2005-05-21 18:34:01: CMP uses abstract schema to map to the physical database

Ashok

• Jun 27th, 2005

In cmp, the cmp bean is given an abstract schema name. In EQL you retrieve the data in a bean using these schema names.

Mohan

• May 21st, 2005

CMP uses abstract schema to map to the physical database

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Ashok

• Jun 27th, 2005

A select method is similar to a finder method for Entity Beans, they both use EJB-QL to define the semantics of the method. They differ in that an ejbSelect method(s) are not exposed to the client and the ejbSelect method(s) can return values that are defined as cmp-types or cmr-types. 

Rajesh

• Jun 15th, 2005

Select method is not there in EJBs

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suresh chowdary

• Jun 14th, 2005

Pooling of instances.  in stateless session beans and Entity Beans server maintains a pool of instances.whenever server got a request from client, it takes one instance from the pool and serves the client request.

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RajeshRokkam

• Jun 3rd, 2005

One of the fundamental concepts of Entity Beans is that they are the pooled objects.Instance pooling is the service of the container that allows the container to reuse bean instances,as opposed to cre...

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RajeshRokkam

• Jun 3rd, 2005

Two Entity Beans are said to be Identical,if they have the same home inteface and their primary keys are the same.To test for this ,you must use the component inteface's isIdentical() method.

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Rajesh Rokkam

• Jun 3rd, 2005

Yes,undefined primary keys are possible with Entity Beans.The type is defined as java.lang.Object.

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Answer posted by Mohan on 2005-05-21 17:15:36: CMR and sub classing of the CMP bean by the container

Mohan

• May 21st, 2005

CMR and sub classing of the CMP bean by the container

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Answer posted by Mohan on 2005-05-21 17:14:47: CMR - Container Managed Relationships allows the developer to declare various types of relationships between the entity beans

Mohan

• May 21st, 2005

CMR - Container Managed Relationships allows the developer to declare various types of relationships between the entity beans

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Answer posted by Mohan on 2005-05-21 17:08:14: Session Context Contains information that a Session Bean would require from the container  Entity Context contains the information that an Entity Bean would require from a container

Mohan

• May 21st, 2005

Session Context Contains information that a Session Bean would require from the container  Entity Context contains the information that an Entity Bean would require from a container

kanth

• Apr 28th, 2005

Entity beans use a subclass of EJBContext called EntityContext. Session beans use a subclass called SessionContext

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Answer posted by Mohan on 2005-05-21 17:07:03: JNDI Context Provides a mechanism to lookup resources on the network Initial Context constructor provides the initial context. Session Context has all the information a session bean would require from the container Entity Context has all the information that an Entity bean would need from a container Ejb Context contains the information...

Mohan

• May 21st, 2005

JNDI Context Provides a mechanism to lookup resources on the network Initial Context constructor provides the initial context. Session Context has all the information a session bean would re...

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