Etch – Distributed Notification Hub

Etch separates order processing from notification delivery, so a slow or broken email provider never makes an order fail or makes a customer wait.

Key ideas

• The order service answers right away and publishes an event to Kafka
• A notification service sends the emails and texts in the background
• Failed sends retry with exponential backoff
• Sends that can never succeed go to a dead-letter topic instead of being lost
• Redis stops duplicate messages when Kafka redelivers an event
• Five services, each in its own container, set up to deploy to AWS ECS with GitHub Actions

Built with: Java, Spring Boot, Spring Cloud Gateway, Apache Kafka, MySQL, Redis, Testcontainers, Docker, GitHub Actions, AWS

Code: github.com/marlware/etch