ActiveMQ Interview Questions

ActiveMQ is an open-source message broker that is basically written using Java programming language. It is mainly written using the Java Message Service (JMS). The benefit of such an open-source – messaging broker is that it provides some executive features to enterprises, which implies that a particular communication can be promoted from one client to another.

JMS is an acronym for Java Message Service. It is an application program interface (API) primarily produced by Sun Microsystems. These applications support a variety of formal communications also known as messaging, especially between different computers within a network. The main function provided by JMS is that it acts as a common interface for standard messaging protocols and in addition, acts as a special messaging facility in order to support various Java programs.

The biggest advantage of using ActiveMQ over other databases is that it is one of the most reliable open sources to communicate and transfer information between different distributed processes.

Some of the components available in JMS include:

• Native clients
• JMS client
• Administered objects
• JMS provider
• Messages

The core objectives required by a JMS – enabled application include the following:

• A connection object
• An appropriate sender or receiver or publisher inside a particular session
• One or more sessions that have the ability to provide context specific to message sending as well as receiving
• A queue object within sessions representing destinations within brokers

Some essential parts of JMS applications include:

• Message
• Message provider
• Message receiver
• Connection
• Server
• Connection factory
• Connection destination

AMQP is an acronym for Advanced Message Queue Protocol. It is a description as to how clients can send messages and how brokers can interpret and exchange information. It follows a wire-level protocol between brokers and clients for effective and efficient communication. It is not entirely a messaging system alike ActiveMQ, however, it is only a messaging protocol.

Some of the common platforms supported by ActiveMQ include:

• Any java platform that has an update of 5.0 or more.
• J2EE 1.4 is another platform
• JMS 1.1
• JCA 1.5 resource adaptor

The following code can help a user change a default username or password:

Change from

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
admin: admin, admin
user: user, user 

To

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
NewUserName: NewPassword, admin
user: user, user

ActiveMQ is a messaging service that has extensive features to support both the broker and the client. While on the other hand, Mule is an ESB that has the capabilities to provide executive features to only the broker by exchanging messages among different software components.

The architecture of Mule is such that it is designed to deliver achievable programming setup for integration of applications between the database and an operating system. However, mule does not support any kind of system for native messaging, thus it is generally used alongside with ActiveMQ. In order to incorporate Mule with ActiveMQ, the user is required to introduce different and unique frameworks to define various boundaries for connectivity.

Fuse Message Broker is an affirmed dispersion of Apache ActiveMQ given by FuseSource. FuseSource does the majority of its improvement and settles bugs as a component of the Apache ActiveMQ community, so there are no practical contrasts between the two. FuseSource may accomplish more successive discharges than Apache may, so it is conceivable to get bug fixes from a Fuse Message Broker discharge sooner than from an official Apache ActiveMQ discharge.

• With the assistance of an application server, the server session is made and it stores them within a pool
• In order to place messages in JMS sessions, an association buyer utilizes the server’s session
• A server session is the one that makes the JMS session
• Application composed by Application software engineers makes the message audience.

The customer using the application such as the JavaBeans firstly parts and segments the web in order to be able to send or receive JMS message synchronously. In addition to that, the customer using the application can also likewise get message non – concurrently. With the assistance of message-driven beans, JMS supplier can alternatively execute the preparation of messages. The message-driven beans are a kind of big business bean that empowers the offbeat utilization of various kinds of messages. The task of sending and accepting message is completed and is in conveyed, which then permits JMS tasks and database to get inside a solitary exchange.

The MOM (Message Oriented Middleware) is a service that fills in as a transition between two conveying segments. MOM is kept in between the customer and server so that it gives the office of passing message by utilizing the procedure lining. Until the customer does not demand to peruse the message, the messages will be kept away in line. By utilizing this procedure, the product segment can work freely of time.

Spread Toolkit is a C++ library for informing and just has incomplete help for JMS. It does not bolster sturdy informing, exchanges, XA or full JMS 1.1. It is likewise reliant on a local code Spread inspiration running on the machine. While on the other hand, Apache ActiveMQ is the JMS supplier utilized in Apache Geronimo and is J2EE 1.4 affirmed in Geronimo and is 100% unadulterated version of Java programming language. ActiveMQ underpins transient and sturdy informing, exchanges, XA, J2EE 1.4, JMS 1.1, JCA 1.5 just as loads of various highlights like Message Groups and Clustering.

In order to monitor the connection between the broker and the client, one needs to monitor the state of the connection using the “addTransportListener()” method.

Difference between synchronous and asynchronous messages