From Ruby to Java: Migrating a Notification Platform to Microservices

At Remember (a career networking platform in Korea), our notification service had been running on a legacy Ruby-based architecture for years.

As the number of users and notification channels grew, we started facing challenges in scalability, maintainability, and operational complexity. The system had accumulated technical debt, making it increasingly difficult to introduce new features and ensure reliable delivery.

Instead of performing a risky big-bang migration, we gradually rebuilt the notification platform as Java-based microservices while continuing to serve production traffic.

In this talk, I will share:

• Why we decided to migrate from Ruby to Java
• How we decomposed the existing architecture
• Strategies for running old and new systems in parallel
• Challenges around message delivery, consistency, and monitoring
• Lessons learned from operating the migration in production

This session focuses on practical engineering decisions rather than theory, providing insights that teams can apply when modernizing long-running systems.