A message broker software ensures applications, systems, and services communicate with each other through the exchanging of information in messages. Messages are monitored and managed while the broker ensures messages are delivered. Message brokers are capable of validating, storing, routing, and delivering messages to the appropriate destinations. Brokers are intermediaries between applications that allow senders to issue messages without knowing how many active or dormant receivers exist.
A message broker translates messages between formal messaging protocols among applications, systems, and services. Independent services can then communicate directly with each other, even if written in different languages or implemented on different platforms. Brokers are software modules with message middleware solutions that give developers a standardized means of handling the flow of data between applications.
The most popular message brokers include Apache Kafka, Redis, RabbitMq, ActiveMQ, and Kestrel, all of which differ for scalability, data persistency, data capabilities, and consumer capabilities. Applications use messaging middleware to simplify the challenge of communication and create a common communication infrastructure that’s scalable.
Publish and Subscribe Messaging
With a publish and subscribe message system, producers publish messages on a topic name that are consumed by subscribers. Many producers can publish messages on the same topic name and many subscribers can receive them. When a subscriber subscribes to a topic, they also receive all messages published on the topic name.
Publish and subscribe messaging is a form of asynchronous messaging for service-to-service communication used in serverless and microservices architectures. Any message deployed to a topic thread is instantly received by all subscribers to the thread. Asynchronous messaging can enable event-driven architectures or decouple applications to increase performance, reliability, and scalability.
A message topic is similar to a message queue and provides a lightweight mechanism to broadcast event notifications. Message queues store messages until they are retrieved by subscribers. Message topics deploy messages with little to no queuing and push them to all subscribers immediately. Subscribers can then perform different functions and do something different with the message. Publishers are unaware of who is consuming messages and subscribers are unaware of who publishes them.
Point-to-point communications have one producer and one consumer. Messages sent by the producer are stored in a message queue until they are received by the consumer. The producer sends a message to the queue, which is retrieved by the message consumer who acknowledges receipt of the message. Multiple producers can send messages to the same queue and more than one message consumer can retrieve messages.
Message Broker Models
Server-based message broker architectures have many advanced features such as centralized processing, message distribution, and data persistence. Java Message Service (JMS) implementations and open-source products like Apache Kafka are examples of proprietary message brokers. There are some instances when a decentralized communications architecture is necessary. The peer-to-peer approach features a mechanism to support direct communication between applications for low latency use cases.
Using message brokers can address a range of business needs within diverse enterprising computing environments. Brokers create a reliable communication backbone for inter-application communication and assured message delivery. There are plenty of use cases for message brokers. Financial transactions and payment processing use a message broker for transaction management and to assure that payment information won’t be lost or duplicated. A message broker also provides proof of receipt and allows applications to communicate when intermediary networks are down.
E-commerce order processing and fulfillment require a reliable website and e-commerce platform. Message brokers can improve fault tolerance and guarantee the successful deployment and single consumption of messages when processing online orders. Both asynchronous message brokers and synchronous message brokers protect sensitive data both at rest and in transit. This is valuable for organizations that face high-security risks and benefit from a message protocol with end-to-end encryption capabilities.