Mastering Event Design: The Ultimate Checklist

This isn’t just a list; it’s a playbook for building bulletproof, scalable, and efficient event-driven systems. Use it to refine your architecture and ensure every event tells the right story, at the right time, in the right way.

• Craft Events with Purpose
  🎯 Goal: Every event should have a clear mission. Is it telling a story, triggering an action, or documenting a state change?
  🔍 Key Action: Use meaningful eventType values rooted in Domain-Driven Design (DDD).

• Nail the Granularity Sweet Spot
  ⚖️ Balance: Too big, you overload systems; too small, you flood the pipes.
  💡 Pro Tip: Right-size events based on domain needs for optimal flow.

• Control the Lifecycle
  ⏳ Keep It Fresh: Version your schemas and let old events gracefully retire.
  🗂️ Checklist: Define clear expiration (TTL) to avoid stale data cluttering your system.

• Think Lean: Minimise Data
  ✂️ Trim the Fat: Only keep what’s necessary. Extra data is a liability.
  🛡️ Compliance First: Stick to GDPR or other privacy standards.

• Be Observant with Observability
  🕵️‍♂️ Trace It All: Correlation IDs and audit logs are your detectives for event mysteries.
  🎛️ Bonus: Make debugging a breeze by linking related events.

• Turn Errors into Opportunities
  🚦 Catch and Release: Use Dead Letter Queues (DLQs) to handle the unhandled.
  🧰 Toolkit: Include error metadata to ensure seamless fallback.

• Validate Like a Pro
  ✅ Stay Strict: Validate schemas rigorously to keep your pipeline clean.
  🔄 Future-Ready: Build for evolution with forward and backward compatibility.

• Make Idempotency Your Superpower
  🛡️ Shield Against Dupes: Design handlers to process events only once.
  🧩 Key Action: Use unique identifiers for deduplication.

• Ensure Global Uniqueness
  🌍 One in a Million: Every eventId must be globally unique to prevent chaos.
  🔑 Key Action: Use UUIDs or similar strategies.

• Respect Dependencies
  🔗 Chain of Command: Maintain event causality to preserve workflows.
  📅 Guarantee: Respect dependencies and event order.

• Stay in Order
  🧮 Count on It: Use sequence numbers or partitions for strict ordering.
  🚂 Pro Tip: Avoid order chaos in distributed systems.

• Prioritize the Important
  🔥 Critical Path: High-priority events (like security alerts) go to the front of the line.
  🧠 Smart Queueing: Define and honor event priority levels.

• Scale Like a Champion
  📈 Grow Without Pain: Keep payloads light and systems ready for horizontal scaling.
  🚀 Go Fast: Batch where needed but don’t compromise latency.

• Retention That Makes Sense
  🗄️ Don’t Hoard: Retain only what’s valuable; archive the rest.
  📜 Policy Time: Set clear retention and archival rules.

• Lock It Down
  🔐 Secure the Signal: Encrypt payloads and enforce authentication.
  🛡️ Access Control: Role-based permissions keep things tidy.

• Evolve with Grace
  🦋 Seamless Changes: Version and deprecate schemas without breaking systems.
  🌟 Flexibility First: Compatibility ensures happy consumers.

• Master the Replay Game
  🎥 Play It Again: Enable safe and idempotent replays.
  🕹️ Controlled Action: Prevent unintended side effects.

• Cut Latency, Gain Speed
  ⚡ Fast and Furious: Monitor delays and optimize pipelines.
  🎯 Critical Wins: Prioritize low-latency pathways for vital events.

• Say No to Fatigue
  🙅 No Spam: Ensure consumers only receive relevant events.
  📦 Filters Rule: Implement smart subscription and filtering strategies.

• Simulate and Dominate
  🎮 Test the Worst: Use mock events and chaos testing to fortify systems.
  🔮 Predictability: Ensure your system thrives under stress.

• Play Nice with Others
  🤝 Interoperability Wins: Use standard protocols like Avro, JSON, or Protobuf.
  📜 Document Everything: Help others understand your event schema.

• Be a Monitoring Maven
  📡 Eyes Everywhere: Monitor every corner of your event pipeline.
  🚨 Proactive Alerts: Detect anomalies before they snowball.