Apache ActiveMQ - Overview

What is ActiveMQ?

ActiveMQ is an open source message broker written in Java. It's fully compliant with JMS 1.1 standards. It is developed and maintained by Apache Software Foundation and is licensed under Apache license. It provides high availability, scalability, reliability, performance and security for enterprise level messaging applications.

JMS is a specification that allows development of message based system. ActiveMQ acts as a broker of messages which sits in between applications and allows them to communicate in asynchronous and reliable way.

Types of Messaging

There are two types of messaging options explained below for better understanding.

Point to Point

In this type of communication, the broker sends messages to only one consumer, while the other consumers will wait till they get the messages from the broker. No consumer will get the same message.

If there are no consumers, the Broker will hold the messages till it gets a consumer. This type of communication is also called as Queue based communication where the Producer sends messages to a queue and only one consumer gets one message from the queue. If there is more than one consumer, they may get the next message but they won’t get the same message as the other consumer.

Publish/Subscribe

In this type of communication, the Broker sends same copy of messages to all the active consumers. This type of communication is also known as Topic based communication where broker sends same message to all active consumer who has subscribed for particular Topic. This model supports one-way communication where no verification of transmitted messages is expected.