Use Cases and System Design Examples

You now know how the outbox works and what it costs. This lesson shows where that cost is worth paying. It also shows where a simpler design is enough, and it closes with two full system design examples.

When the Pattern Fits

Use the outbox whenever a lost event silently breaks another service. That is the whole test. If nobody would notice the loss until data disagrees, you need the pattern.

Four cases pass this test again and again:

• Saga steps. Every saga step that publishes an event needs it, or the saga stops with no error.
• Search index and cache sync