EJB interview questions are core part of any Java
J2EE interview. As EJB forms business layer for modern J2EE enterprise
application, Good knowledge of EJB is expected from J2EE programmer. Purpose of
these EJB
interview questions is to give an Idea about what kind of questions you can
expect on J2EE and EJB interviews. EJB was always tough for Java programmer
because of heavy weight architecture comprised with many interfaces
e.g. home interface, remote interface, local interface, bean class etc. It take
too much time and knowledge to implement and use EJB in your Java web and
enterprise application forget about challenges posed by application servers like
WebLogic or IBM WebSphere.
All these problem persist till EJB 2.0 which makes EJB infamous along with J2EE and created path for Spring framework which is based on POJO. But with EJB 3.0, Enterprise Java Beans are back again and they are back with bang. In this article I will share some EJB Interview questions from my collection.
These EJB questions are from EJB 2.0 and EJB 3.0 and also related to fundamental concept of using Enterprise Java beans. By the way I don't have answer of these Enterprise Java beans questions but I will update the post once I have answers of all these interview questions asked on EJB interviews.
This article is divided in two category, in first category we will see some common EJB interview questions and in second category we will see EJB 3.0 interview question, which is more popular now days. I have seen EJB question on companies like Capegemini, TCS, CTS, Infosys and Wipro and mostly on finance domain projects
All these problem persist till EJB 2.0 which makes EJB infamous along with J2EE and created path for Spring framework which is based on POJO. But with EJB 3.0, Enterprise Java Beans are back again and they are back with bang. In this article I will share some EJB Interview questions from my collection.
These EJB questions are from EJB 2.0 and EJB 3.0 and also related to fundamental concept of using Enterprise Java beans. By the way I don't have answer of these Enterprise Java beans questions but I will update the post once I have answers of all these interview questions asked on EJB interviews.
This article is divided in two category, in first category we will see some common EJB interview questions and in second category we will see EJB 3.0 interview question, which is more popular now days. I have seen EJB question on companies like Capegemini, TCS, CTS, Infosys and Wipro and mostly on finance domain projects
Common EJB Interview Questions in J2EE
1. What is Enterprise Java Beans (EJB) in J2EE ? What is advantage of using EJB ?
This is the first EJB question
asked to programmers
on beginners and intermediate level. Enterprise Java beans are J2EE component
which is managed by Container provided by Application server and encapsulate
business logic and forms back end of Enterprise Java application. Main advantage
of using EJB is to leverage core services provided by EJB container e.g.
transaction management, persistence, security etc. Also business logic
encapsulate in EJB is good multi-tier design and can be used with different
clients e.g. Web, Desktop and mobile. Current version of EJB is EJB 3.0 which
is based on annotation.
2. Can we run EJB in web server like Tomcat ?
One of the tricky interview question on EJB. No you can not run EJB in
web server like Tomcat. You need application server like Glassfish, WebLogic or
Websphere to run Enterprise Java beans. One of the followup question of this is
What
is difference between Application server and web server. See the link for
answer of that question.
3. What was shortcomings of EJB 2.0 ?
If you have mentioned in your resume that you have worked on EJB 2.0,
then better be prepared for this EJB interview question. It's not difficult to
answer if you have indeed worked in EJB 2.0. There are several pain e.g.
writing those local and remote interfaces, too many boiler plate coding etc.
4. What is advantage of putting business logic in EJB over stored procedure?
This is another tough
Java question on EJB interview. Putting complex business logic in stored
procedure is not a good idea but its been there for long time. Main advantage
of using EJB over stored procedure is that you don't need to port your SQL
Stored procedure code when you change database e.g. form Sybase to Oracle or
Oracle to SQL Server.
5. What are the services provided by EJB container ?
Container is one of the main reason why Programmer should use Enterprise
Java beans. EJB container provide several useful services like :
1) life cycle management of Enterprise Java beans (EJB).
2) Container manged transaction
3) Container managed persistent
4) Security etc
6. What is two phase commit? How do you manage distributed transaction in EJB
This is one of the most tricky
Java question I have seen in EJB interviews. Two phase commit involves one
Transaction manager which controls whole commit process. If you have not used
two phase commit or distributed transaction along with EJB then you need to
explore this topic in detail to answer this EJB interview question.
Couple of more EJB interview questions whose answer will be updated
later.
7) EJB invocation is based upon which design pattern ? What is Service
locator design pattern ?
8) How do you call Enterprise Java beans from Servlet or JSP ?
9) What is difference between Session and Entity beans ?
10) What is Java persistence API or JPA.
11) What is difference between stateless and stateful Session beans ?
12) What is Session facade design pattern used in EJB and J2EE ?
13) What is difference between Session bean, Enttiry bean and Message
driven bean (MDB)
14) Can you create Thread in EJB ?
If you know answer of these EJB practice question than please share as
comment.
Top EJB 3.0 Interview Questions
In this section we will see some EJB 3.0 Interview question. EJB 3.0 is
the most popular version of EJB which surprisingly ease development of EJB by
using annotation based approach. EJB 3.0 is also most popular EJB version in
use.
1) What
is main difference between EJB 2.0 and EJB 3.0 ?
Simple answer is use of Java annotation, ease of development etc.
2) Can
you name few annotation used in EJB 3.0 and what does the do ?
This is another simple EJB 3.0 interview question which can be easily answer if you have coded few EJB 3.0 beans. Some annotations used are @EJB,
@PreDestory, @PostConstruct etc.
3) Does
EJB 3.0 supports dependency Injection ?
4) How to
call a EJB 3.0 bean from Servlet or JSP ?
Use @EJB annotation.
5) What
are the issues you face with EJB 3.0 ?
These were some of the EJB interview questions for practice if you are
going to appear in any Java or J2EE interview which requires EJB skills. There
are not many J2EE programmer who understand and use EJB very well. It was more
difficult when EJB 2.0 was around but much better with EJB 3.0 and EJB 3.1.
Please share if you have any other interesting EJB interview question or if you
know answer of any EJB question shared here.
Other interview question to prepare for J2EE interviews:
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