Messaging and Integration Patterns

First, congratulations. If you’ve made it this far, you’ve explored some of the most powerful design patterns and architectural ideas in the Node.js ecosystem. You’re not just learning Node.js, you’ve been progressing toward mastery, one pattern, one principle, and one chapter at a time.

This final chapter adds the missing piece that makes distributed systems truly work: integration. If scalability is about distributing systems, integration is what holds them together. In the previous chapter, we learned how to split applications across multiple processes and machines. To make those parts useful, they often need to communicate. There are two main ways to do that: use shared storage as a central source of truth, or exchange messages containing data, events, or commands. Messaging is what truly unlocks scalability and flexibility in distributed architectures.

Messages are everywhere: over the internet, between processes...