Phase 04 — Service integration & error handling
The system side: service tasks, delegates, HTTP tasks, BPMN errors vs technical errors, retries, and compensation.
| # | Lesson | Type | Lang | Ships |
|---|---|---|---|---|
| 01 | Service tasks: delegates, expressions, delegate expressions ✅ | Use | Java | module |
| 02 | The HTTP task: calling REST APIs from a process ✅ | Use | XML | process model |
| 03 | BPMN errors vs technical errors: two failure planes ✅ | Concept | — | cheat sheet |
| 04 | Boundary events: catching errors on an activity ✅ | Build | Python | module |
| 05 | Retries & incident handling: what happens when a bureau call fails ✅ | Use | Python | client |
| 06 | Compensation: undoing completed work ✅ | Concept | — | pattern guide |
Prerequisites: Phase 2 (transactions, job executor). Concept reading:
Principles 4–6. Full plan:
ROADMAP.md.