Messaging

Overview

Messaging is the concept of different services (or parts of a service) communicate with each other asynchronously. The Mosaic platform uses RabbitMQ as the message broker that implements all the required options to manage and distribute messages.

This document explains the messaging concepts and what is going on "under the hood". In your daily work, most of this is encapsulated by the Mosaic message bus, so you don’t have to worry about it.

For asynchronous message processing, we use the Mosaic message bus which is based on the Rascal pub/sub wrapper around the amqplib library. The Mosaic message bus adds the notions of events and commands and provides the functionality to easily integrate into the Mosaic Managed Services in a secure way.

The main objective of the messaging folder in services' source code is the setup and registration of the message handlers and middleware to consume messages and the publishers to send out messages. In addition, there is a media message handler that protects message handlers by checking the message for specific permissions.

Decoupling and Scalability

By embracing messaging patterns, Mosaic achieves loose coupling between its microservices. Each service can operate independently, communicating through messages without the need for direct service-to-service calls. This decoupling enhances scalability, as new services can be added or scaled up without affecting existing components.

Fault Tolerance and Reliability

The transactional nature of message processing ensures fault tolerance and reliability. Messages are processed atomically, with retries and error-handling mechanisms built-in. This guarantees that critical operations, such as order processing, payment updates, or inventory management, are executed reliably and consistently.

Asynchronous Processing

Asynchronous messaging allows Mosaic services to handle tasks and events in a non-blocking manner. Long-running operations, such as file processing, notifications, or complex calculations, can be offloaded to background workers, improving system responsiveness and user experience.