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EJB Interview questions


Total available count: 73
Subject - Java Technologies
Subsubject - EJB
1
What is EJB?
2
What is session Facade?
3
What are the key features of the EJB technology?
4
What are the key benefits of the EJB technology?
5
What is message-driven bean?
6
What are Entity Bean and Session Bean?
7
How EJB Invocation happens?
8
Is it possible to share an HttpSession between a JSP and EJB? What happens when I change a value in the HttpSession from inside an EJB?
9
The EJB container implements the EJBHome and EJBObject classes. For every request from a unique client, does the container create a separate instance of the generated EJBHome and EJBObject classes?
10
Can the primary key in the entity bean be a Java primitive type such as int?
11
Can you control when passivation occurs?
12
What is the advantage of using Entity bean for database operations, over directly using JDBC API to do database operations? When would I use one over the other?
13
Brief description about local interfaces?
14
What are the special design cares that must be taken when you work with local interfaces?
15
What happens if remove( ) is never invoked on a session bean?
16
What is the difference between Message Driven Beans and Stateless Session beans?
17
What is an EJB Context?
18
Is it possible for an EJB client to marshal an object of class java.lang.Class to an EJB?
19
Is it legal to have static initializer blocks in EJB?
20
Is it possible to stop the execution of a method before completion in a SessionBean?
21
What is the default transaction attribute for an EJB?
22
What is the difference between session and entity beans? When should I use one or the other?
23
Is there any default cache management system with Entity beans?
24
Why is ejbFindByPrimaryKey mandatory?
25
Why do we have a remove method in both EJBHome and EJBObject?
26
What is the difference between a Server, a Container, and a Connector?
27
How is persistence implemented in enterprise beans?
28
For Entity Beans, What happens to an instance field not mapped to any persistent storage, when the bean is passivated?
29
What is a Message Driven Bean, what functions does a message driven bean have and how do they work in collaboration with JMS?
30
What is the advantage of putting an Entity Bean instance from the Ready State to Pooled State?
31
What is the need of Remote and Home interface. Why can't it be in one?
32
Can I develop an Entity Bean without implementing the create() method in the home interface?
33
Why an onMessage call in Message-driven bean is always a separate transaction?
34
Why are ejbActivate() and ejbPassivate() included for stateless session bean even though they are never required as it is a no conversational bean?
35
Static variables in EJB should not be relied upon as they may break in clusters. Why?
36
If I throw a custom ApplicationException from a business method in Entity bean which is participating in a transaction, would the transaction be rolled back by container?
37
Can a Session Bean be defined without ejbCreate() method?
38
How to implement an entity bean which the PrimaryKey is an auto numeric field?
39
What is clustering?
40
If my session bean with single method insert record into 2 entity beans, how can know that the process is done in same transaction (the attributes for these beans are Required)?
41
When should I adopt BMP and when I should use CMP?
42
What's different in Enterprise JavaBeans 1.1?
43
What is Enterprise JavaBeans?
44
How many development roles are involved in J2EE application?
45
What is an enterprise bean?
46
Are Enterprise JavaBeans and JavaBeans the same thing?
47
How does passivation work in stateful session beans?
48
How does a client application create a transaction object?
49
Do JTS implementations support nested transactions?
50
How does a session bean obtain a JTA UserTransaction object?
51
How does an enterprise bean that uses container-managed transactions obtain a JTA UserTransaction object?
52
Is it possible for a stateless session bean to employ a JTA UserTransaction object?
53
How does an entity bean obtain a JTA UserTransaction object?
54
What are the constraints or drawbacks of container managed EJB's?
55
Is entity data persisted at the end of a transaction or at any time?
56
How do enterprise beans access native libraries?
57
What makes a Java class an enterprise bean?
58
While deploying CMP entity beans, which fields in the bean are container-managed and how are they identified?
59
Does the EJB programming model support inheritance?
60
How should complex find operations be implemented?
61
Can I use Threads in a enterprise bean?
62
Why are beans not allowed to create their own threads?
63
How does EJB support polymorphism?
64
What classes does a client application need to access EJB?
65
What is an EJB primary key? How is it implemented when the database doesn't have a primary key?
66
What's an .ear file?
67
Can beans use stored procedures in a database?
68
What happens when two users access an Entity Bean concurrently?
69
Which fields in beans should be public?
70
How do you implement callbacks in EJB?
71
How do I automatically generate primary keys?
72
How is the passivation of Entity beans Managed?
73
Explain the different Transaction Attributes and Isolation Levels with reference to a scenario?