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Is it necessary to create instance of the bean for each and every request?
vinaykurudi
- Aug 13th, 2008
No, why because beans are maintaining?one bean pool. If any request comes to that bean it will first see in that pool if any instance is free, then that instance will be thrown to the request. If no ...
rogesh
- Jan 19th, 2006
I think 238 instances will created for one bean
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What is the difference b/w EJB2.1 and EJB3.0?
saankhya2003
- Jul 29th, 2008
The main difference lies in the persistence, In case of EJB 3.0 there?is JPA, Java persistence API which makes the mapping of EntityBeans with the database easy, with the help of a service called as ...
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What is the default transaction attribute in transactions
harish.verma
- Mar 6th, 2007
The default choice for a transaction attribute is Required. Using this attribute ensures that the methods of an enterprise bean are invoked within a JTA transaction. In addition, enterprise beans with...
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What kind of bean(entity/session) will you use if there are no database transactions and all you use is a read-only database.
coolguy_krkr
- May 11th, 2008
If you have no database transactions and you need just data fetch..I would not go for both of them..We can as well use simple dao with jdbc call to fetch data. If you have to pick one from the beans then definetely it would be stateless for this scenario.
s_s78
- May 3rd, 2006
If u are only reading the database then u dont need to use Entity been at all.Entity been slows down data fetch operation.U just need to use stateless session bean.
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JNDI
Why is JNDI used.Do we have any alternative for JNDI?
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PortableRemoteObject.narrow()
What is the purpose of the call to PortableRemoteObject.narrow()?
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Entity bean is an abstract class and its local and home interfaces also extends an abstact class. So how can we instantiate home or local interface?
jettyprakash
- Mar 8th, 2008
Clients never dealt with direct instances of Entity Bean. It deals with container implementations of home and component interface (stubs & skeletons - aka deployement code)It is the container responsibility to Wrap a class around the abstract definition of Entity bean.
jayanandan
- Jan 14th, 2008
it is upto container which instantitates and maintain all entity bean in the ejb container.But to act like a entity bean,the developer has to implement EntityBean and all abstract methods defined in i...
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What is deployment descriptor
Answered by Jey on 2005-05-08 12:59:41: Deployment Descriptor is a XML document with .xml extenion. It basically descripes the deployment settings of an application or module or the component. At runtime J2EE server reads the deployment descriptor and understands it and then acts upon the component or module based the information mentioned in descriptor. For example EJB module has a deployment...
kirankpv
- Feb 9th, 2008
Deployment Descriptor is a XML document with .xml extenion. It basically describes the deployment settings of an application . At runtime webcontainer reads the deployment descriptor and understa...
Jey
- May 8th, 2005
Deployment Descriptor is a XML document with .xml extenion. It basically descripes the deployment settings of an application or module or the component. At runtime J2EE server reads the deployment des...
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What is the difference between Stateful session bean and Stateless session bean
Answer posted by Mohan on 2005-05-20 08:45:36: Stateful session beans have the passivated and Active state which the Stateless bean does not have.
srikanthm2
- Jan 28th, 2008
Stateful session beans follow the instance passivation techniqueStateless session beans follow the instance pooling technique.ejbActivate() and ejbPassivate() methods are not called in Stateless session beansI
Jeevan Sunkersett
- Jul 16th, 2007
Stateful Session Bean (SFSB) do not have the concept of pooling
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When are transaction propagated webcomponet(servlet,jsp) to EjbComponent?
shankarsunmicrosys
- Jan 17th, 2008
Transaction will be propogated from web tier to EJB tier, when the client code (web tier) is already in the transaction and server method (EJB) which is getting called has some transaction attributes like required,supports,mandatory etc.
Sree kumar
- Aug 16th, 2006
In the jsp the lookup of the jndi names comes then access the ejb component..for more clarrification keep in touch with this subject...
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What is meant by Serialization and Externalization? Serialization is a Marker interface,so what is the use of WriteObject() anf ReadObject(), Where it is actually used? Give me some real time examples?
avisnk
- Dec 20th, 2007
It will be caught in the methodone() catch block....ANy exception thrown will be look for a corresponding catch method...if not present, then look for the catch block in the caller method and so on....Since methodtwo() of urs doesnt have one it will be caught in the methodone() catch block......
Chaitanya . I
- Aug 11th, 2007
methodOne(){ try{ int i; System.out.println( i++); method...
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EJB local and home interfaces
Is there any special reason to write two interfaces in ejb(local , home interfaces ). why don't we write only one interface .
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Deployment descriptor
Why do we require to write a deployment descriptor (ejb-jar.xml) in an xml format ? why don't we write it in a java file ?
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What is the difference between optimistic locking and pessimistic locking
Answer posted by Mohan on 2005-05-21 17:20:02: Optimistic locking assumes that no one would read or change the data while changes are being by a bean Pessimistic locking would rather lock down the data so that no one can access it
rossbertoloni
- Sep 3rd, 2007
Optimistic LockingIs based on the assumption that it is unlikely that separate users will access the same object simultaneously. The EJB does not hold a lock for the duration of the transaction,...
John
- May 28th, 2005
In optimistic locking the row will not be locked until the actual update is performed. In order to prevent the lost update issue a version number column will be used. In pessimistic locking the row wi...
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What is JMS and Message Driven Bean. Explain with some examples.
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EJB Interview Questions
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