Java J2ee Struts Hibernate Spring Interview Questions Java J2ee Struts Hibernate Spring Interview Questions

1. What s the difference between queue and topic in JMS ?

A queue means a message goes to one and only one possible subscriber.

A topic goes to each and every subscriber.

Topics are for the publisher-subscriber model, while queues are for point-to-point.

A JMS topic is the type of destination in a 1-to-many model of distribution.

2. Can you explain about database normalization ?

Database normalization is a process used to organize a database into tables and columns.
The idea is that a table should be about a specific topic and that and only supporting topics included.
By limiting a table to one purpose you reduce the number of duplicate data contained within your database.
This eliminates some issues stemming from database modifications.

Why you will not put all the data in a single table ?
Splitting up of all data into several tables and later fetch data by sql queries.

There are three main reasons to normalize a database. 
The first is to minimize duplicate data,
the second is to minimize or avoid data modification issues,
and the third is to simplify queries.
There are three common forms of database normalization: 1st, 2nd, and 3rd normal form.
They are also abbreviated as 1NF, 2NF, and 3NF respectively.
There are several additional forms, such as BCNF,
Boyce-Codd normal form (or BCNF or 3.5NF) is a normal form used in database normalization.
It is a slightly stronger version of the third normal form (3NF).
BCNF was developed in 1974 by Raymond F Boyce and Edgar F Codd to address certain types of anomalies not dealt with by 3NF as originally defined.

3. What?s the difference between a queue and a stack?

Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO rule

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