Introduction
Enterprise messaging software or Message Oriented Middleware has been in existence since the late 1980s. Message Oriented Middleware is a concept that involves the passing of data between applications using a communication channel that takes messages from the sender to the receivers. These messages are transferred in an asynchronous manner between the sender and receiver using a message broker.
These kinds of messaging systems help in decoupling applications and keeping the sender and receiver anonymous from each other. There are many such messaging systems available in the market these days like Apache Kafka, RabbitMQ, ActiveMQ, AmazonMQ, and many more, though this article is based on ActiveMQ.
What is ActiveMQ?
Active MQ is widely used Message Oriented Middleware which offers standards-based, message-oriented application integration across various languages including C#, Java, Python, Ruby, etc. ActiveMQ was developed as an open-source project by Apache Foundations.
Why was it made?
Back in the early 2000s, there were not many message brokers that were open sourced or free to use or available with non-commercial licenses. Most of the Enterprise Messaging software and MOM used to be really expensive to buy and support. This prompted a group of open source developers to start building an alternative.
Though it was first meant to be a JMS implementation for the Apache Geronimo project, issues and concerns mentioned above prompted the developer to build an open-source message broker, ActiveMQ.
How does it work?
To know
how ActiveMQ works, we need to look at how JMS works as ActiveMQ is an open-source implementation of
JMS at its core. JMS is a Java API for enterprise messaging. JMS consists of multiple components that are responsible to establish a proper communication mechanism between the sender and receiver.
First, we have a JMS Provider that delivers control and administrative features and implements the necessary interface to make message transfer. Then we have the JMS clients which are none other than the senders and receivers who use the JMS for message transfers. Then we have JMS objects that consist of the Destinations and Connection factories and finally the actual message which is to be sent from the sender to the receiver using JMS.
Now, as we are aware of all the components involved in JMS, let’s see how these components are used in ActiveMQ to establish communication between senders and receivers by looking at various use cases.
Let’s consider we have two applications, namely Application A and B. Suppose application A wants to communicate with Application B. In this case, Application A sends a message to our MOM, ActiveMQ, which then delivers it to Application B.
Here, Application A is the producer, and Application B is the consumer.
Under the hood, the message sent by the Application is stored in the Queue or Topic of the broker. Upon receiving the message in the Queue or Topic, it then sends the message to the consumer.
In the above, we have described one of the features offered by ActiveMQ. Further, ActiveMQ supports two styles(domain) of messaging, namely Point to Point and Publish/Subscribe. Let’s discuss what Point to Point messaging style refers to and post that we’ll discuss what Publish/Subscribe Model is.
In the Point to Point messaging style, we send messages in a synchronous as well as asynchronous manner using Queues. The message, sent by the producers, is sent to the consumer using the queue. Each message is delivered to the queue only once to a single consumer.
In the Publish/Subscribe messaging style, We call our producers as publishers and consumers as subscribers. Here, we use something called, Topics to convey the messages among these producers and consumers. To receive messages, consumers need to subscribe to the topic. And once our consumers are registered to the topic, every time a message is sent by the Producer, all the consumers receive the messages.
It’s more like you subscribe to a YouTube channel and every time the YouTube channel publishes a video, you and all the other subscribers get a notification.
When should we use ActiveMQ?
There are various scenarios in which using ActiveMQ would be wise and helpful for the overall function of our application as well as the architecture of the system. Some of them are listed below:
- To Increase Scalability of the Application
- Replacing RPCs
- Integrating heterogeneous applications
- Reduce the coupling between the applications
Apart from the above-mentioned scenarios, there are many other scenarios where ActiveMQ can be handy to use. Let’s discuss one such scenario where ActiveMQ helps the application. Let’s discuss how ActiveMQ can help in the case of heterogeneous applications.
Suppose we have two applications, namely Application A and Application B. Application A is written in Java while Application B is written in Python. Now, let’s say that due to some requirements, you wanted to establish communication between these applications.
Normally, this would be really difficult to do between two applications written in different languages unless you have a common medium of communication between them.
ActiveMQ helps you do so without a lot of trouble. As ActiveMQ provides clients for multiple languages including .Net, Python, Ruby, and many more languages which helps in sending messages between heterogeneous applications via its message broker.
Now as we have discussed enough about ActiveMQ, how it works, and the scenarios where it is helpful to use it, let’s discuss the Advantages of ActiveMQ.
Advantages of ActiveMQ
- Highly Scalable
- Open Source
- Easy to use
- Broker Clustering
- Supports multiple protocols like HTTP/HTTPS, STOMP, UDP for connectivity
- Offers client APIs for multiple languages like Java, .Net, Python, Ruby, and many more languages.
- It allows you to customize the authorization and authentication required for your communication as per your requirement or needs.
- Provides reliable communication between the producer and consumers.
Alternatives for ActiveMQ
RabbitMQ
RabbitMQ is a message broker that gives your application a common platform to send and receive messages and in case some of the messages aren’t delivered it provides them storage space to live until they are executed.
Kafka
Kafka is a messaging queue tool built to help software applications communicate with each other in an asynchronous manner. Kafka was made to enable real-time streaming of data transmission and is an open-source tool that users can use for free and allows open source contribution too.
IBM MQ
IBM MQ is a MOM that can send any kind of messages, enabling the organization to build loosely coupled, reusable architectures such as service-oriented-architecture (SOA). IBM MQ provides a messaging layer for visibility and control of the way in which messages and data are sent inside and outside of the organization.
ZeroMQ
ZeroMQ is a popular messaging library which is highly efficient and works asynchronously primarily used in distributed applications. It provides a message queue to enable the transfer of messages but without having the need to have a dedicated message broker which is a necessity for most message-oriented middleware.
Amazon MQ
Amazon MQ is a cloud-based message broker which is an implementation of Apache Active MQ. It makes it easy to set up and operate message brokers in the cloud.
Conclusion
Apache Active MQ is one of the most widely used message-oriented middle-ware that uses messaging to connect remote applications in various languages. It supports multiple messaging protocols like AMQP, Web Sockets, Stomp, OpenWire, and MQTT.
The primary work of ActiveMQ is to send messages between multiple applications. It is an open-source project thus does not need any commercial license to use as well as has great support from open source contributors.
If you need enterprise-level support, however, there are several commercial companies out there that offer such services for open source software, including OpenLogic, HYTE, Total Transaction Management (TTM), or Yupiik.
Apache Active MQ enables the communication between heterogeneous applications with support for a wide variety of Client APIs to enable message sharing between applications built in multiple languages.