EJB 3.0 Interview Questions You'll Most Likely Be Asked

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EJB 3.0 Interview Questions You'll Most Likely Be Asked is a perfect companion to stand ahead above the rest in today’s competitive job market. Rather than going through comprehensive, textbook-sized reference guides, this book includes only the information required immediately for job search to build an IT career. This book puts the interviewee in the driver's seat and helps them steer their way to impress the interviewer.


Table of Contents
1. EJB Environment
2. Enterprise Beans
3. Session Beans
4. JPA(Java Persistence API)
5. EJB 3.0 Entities & Persistence
6. MDB (Message Driven Bean)
7. HR Questions


a) 200 EJB Interview Questions, Answers and Proven Strategies for getting hired as an IT professional

b) Dozens of examples to respond to interview questions

c) 51 HR Questions with Answers and Proven strategies to give specific, impressive, answers that help nail the interviews

d) 2 Aptitude Tests download available on www.vibrantpublishers.com


Sample from the book
(Below Questions and Answers are randomly taken from different pages of the book)

133: What is @DiscriminatorColumn and @DiscriminatorValue annotation?
The super root class is signed with @DiscriminatorColumn to indicate which column in the table is used to store the discriminator value. The @DiscriminatorValue annotation is used with the inherited classes to indicate which column is mapped with which entity.


134: What is the advantage of single table inheritance model?
In single table inheritance, as all the entities are stored in a single table no Join is required to retrieve the entities. Insert and update is also easy to perform.


135: Will you use single table hierarchy if the hierarchy model is wide?
You can always use single table hierarchy model. But in case of a wide hierarchy all the columns need to be stored in a single table and in that case there may be many columns with null values.


136: Describe the strategy used in joined table hierarchy?
In this strategy the top level entity is mapped with a table that contains all the fields common to all the entities and the inherited entities are mapped to a table specific to that entity only. So at the time of reassemble, Join is performed to retrieve the entire hierarchy.


137: Which annotation is used to indicate primary key?
The @PrimaryKeyJoinColumn annotation is used to indicate primary key.


138: What are the advantages of joined table strategy?
This strategy is advantageous because we are not disturbing the existing table in the database. Rather we are creating tables for new entities and they are related with the parent entity by primary-foreign key relationship.


139: Can we use normalization in joined table strategy?
Yes, we can use normalized schema while using joined table strategy without any redundant data.


140: Does joined table strategy have any impact on the performance?
For retrieving entity hierarchy, we need to join tables which might take long time and complex query if the hierarchy is complex itself.


141: If you have a complex data model, which strategy should be used?
In a complex data model with complex relationship, joined table strategy is best fit.


142: What is table per class inheritance?
In this strategy super class and subclasses are stored in their own tables without any relationship.