Introduction to Message Brokers

Key definitions

• A key feature used in many software designs and architecture are the messages brokers. A message broker is a cross-application communication technology that helps build common integration mechanisms to support cloud-native, microservices-based, serverless, and hybrid cloud architectures.
• Message Brokers enable the programmers to build applications, systems and services to communicate with each other and exchange information. On that same process they can validate, store, route, and deliver messages to the appropriate destinations.
• To provide reliability they often rely on message queue structures where they store the massages in order until they are fully consumed by the application. So they will normally follow a FIFO(First In First Out) method to organize and process the queue in order to process all messages that are in the queue

Message broker models

Peer-to-peer messaging

• This is the distribution pattern used in message queues with a one-to-one relationship between the sender and the consumer of the message. Each message in the queue is sent to only one recipient and processed only once. This method is used when the message only had to be executed once
  • A good example for this messaging pattern is a payroll/financial transaction processing. In these kinds of systems, both senders and receivers need a guarantee that each payment will be only be process once.

Publish/subscribe messaging

• In this message distribution pattern, commonly referred to as "pub/sub", works with the idea that each message is published to a topic, and all the multiple message consumers that are subscribed to the topic will/want to receive those messages. All messages published on a topic will be distributed to all subscribed applications. This is basically a broadcast distribution method where we have a one-to-many relationship between the publisher of a message and its consumer.
  • A good scenario and example where we can use this kind of message distribution pattern will be in an airline company where they will have to release updated information about the flights, and that information could be used by multiple systems since ground crew performing aircraft maintenance, refueling, baggage handlers, flight attendants, pilots preparing the aircraft for the flight, operator visual displays to inform the public, and many others possibles systems

Here we have a more basic visual example of how does work those mainly used message broker models