Reactor Under the Hood: Building a Graph-Based Saga Orchestrator in Elixir, James Harton | Code BEAM

✨ This talk was recorded at Code BEAM Europe in November 2025. If you're curious about our upcoming event, check https://codebeameurope.com/ ✨ --- Here's the thing - workflow engines sound complicated, but they don't have to be. I'll show you how Reactor uses a dead simple graph algorithm (find nodes with no dependencies, run them, remove them, repeat) to build something genuinely useful. We'll dig into how this basic approach, combined with OTP, gives you concurrent execution with concurrency limits, automatic retries, compensation when things go wrong (and they will), and the ability to compose workflows inside each other. You'll see how we made the simple cases easy without making the complex cases impossible. --- Let's keep in touch! Follow us on: 💥 Bluesky: / codebeam.bsky.social 💥 Twitter: / codebeamio 💥 LinkedIn: / code-sync