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JMS Interview Questions and Answers
What is JMS?
A1:
Java Message Service: An interface implemented by most
J2EE containers to provide point-to-point queueing and
topic (publish/subscribe) behavior. JMS is frequently
used by EJB's that need to start another process
asynchronously.
For example, instead of sending an email directly from
an Enterprise JavaBean, the bean may choose to put the
message onto a JMS queue to be handled by a
Message-Driven Bean (another type of EJB) or another
system in the enterprise. This technique allows the EJB
to return to handling requests immediately instead of
waiting for a potentially lengthy process to complete.
A2:
The Java Message Service (JMS) defines the standard for
reliable Enterprise Messaging. Enterprise messaging,
often also referred to as Messaging Oriented Middleware
(MOM), is universally recognized as an essential tool
for building enterprise applications. By combining Java
technology with enterprise messaging, the JMS API
provides a powerful tool for solving enterprise
computing problems.
A3:
JMS stands for Java Messaging Service which is developed
by Sun Microsystems . JMS Provider allow applications
which are running on different systems can communicate
with each other asynchronously . Many EAI tools support
JMS as their standard messaging service.
A4:
The Java Message Service is a Java API that allows
applications to create, send, receive, and read
messages. Designed by Sun and several partner companies,
the JMS API defines a common set of interfaces and
associated semantics that allow programs written in the
Java programming language to communicate with other
messaging implementations.
A5;
JMS stands for Java Message Service. It allows
applications to communicate through reliable, scaleable,
and asynchronous text messages and objects over the
network.
A6;
Java Message Service (JMS) is the new standard for
interclient communication. It allows J2EE application
components to create, send, receive, and read messages.
It enables distributed communication that is loosely
coupled, reliable, and asynchronous.
A7;
JMS is an acronym used for Java Messaging Service. It is
Java's answer to creating software using asynchronous
messaging. It is one of the official specifications of
the J2EE technologies and is a key technology.
Must I place all my class files in the WEB-INF folder
and all JSP's outside?
A1:
The class files should place into WEB-INF/classes folder
and the JSP files should place within a separate folder.
A2:
Yes! Otherwise the web server/ application server cannot
access the .jsp files and classes.
The java class files can be placed either in WEB-INF/lib
or WEB-INF/classes. But it is recommended to put the
class files in WEB-INF/classes. The server will load the
files from the classpath so it just will not matter
where the class is.
A3:
Yes, class files is private resources, so you must store
class in WEB-INF/classes folder.
JSP and HTML files should be placed outside.
A4:
Class files inside web-inf cannot be access by browsers,
while the JSP files are meant for accessible by browsers
so, it may be strictly place outside the web-inf only.
A5:
Here is structure of web app.
web (this folder is Accessible from www)
Store all your JSP and HTML files here
WEB-INF (this folder is not Accessible )
classes (store your classes here, classes you are using
in jsp
lib (store 3rd party jars)
A6:
1. Class files - Either they must be in WEB-INF\classes
directory OR you can package them as JAR and put in
WEB-INF\lib
2. JSP files - Depends how do you design your arch. If
you have controller/delegator that can forward requests
to JSPs, you can keep them under WEB-INF directory also.
If not, you have to keep them outside WEB-INF.
A7:
The Java Message Service (JMS) API is a messaging
standard that allows application components based on the
Java 2 Platform, Enterprise Edition (J2EE) to create,
send, receive, and read messages. It enables distributed
communication that is loosely coupled, reliable, and
asynchronous
What type messaging is provided by JMS?
Both synchronous and asynchronous.
How may messaging models do JMS provide for and what are
they?
JMS provides for two messaging models,
publish-and-subscribe and point-to-point queuing.
What is the point-to-point model in JMS?
A point-to-point model is based on the concept of a
message queue: Senders send messages into the queue, and
the receiver reads messages from this queue. In the
point-to-point model, several receivers can exist,
attached to the same queue. However, (Message Oriented
Middleware)MOM will deliver the message only to one of
them. To which depends on the MOM implementation.
What are the advantages of JMS?
One of the principal advantages of JMS messaging is that
it's asynchronous. Thus not all the pieces need to be up
all the time for the application to function as a whole.
What is the publish-and-subscribe model in JMS?
A publish-subscribe model is based on the message topic
concept: Publishers send messages in a topic, and all
subscribers of the given topic receive these messages.
What is JMS administered object?
A preconfigured JMS object (a resource manager
connection factory or a destination) created by an
administrator for the use of JMS clients and placed in a
JNDI namespace
What is publish/subscribe messaging?
With publish/subscribe message passing the sending
application/client establishes a named topic in the JMS
broker/server and publishes messages to this queue. The
receiving clients register (specifically, subscribe) via
the broker to messages by topic; every subscriber to a
topic receives each message published to that topic.
There is a one-to-many relationship between the
publishing client and the subscribing clients.
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