📜 Diagram for Lesson 9: Error Handling in Workflows
Visualizing Error Handling & Compensation Patterns
Error handling patterns including the Saga pattern with compensation logic and circuit breaker implementation
Error Handling Flow with Compensation
flowchart TD
A[Start ErrorHandlingWorkflow] --> B[Try: Validate Order]
B --> C{Validation Success?}
C -- Yes --> D[Try: Reserve Inventory]
C -- No --> E[Throw OrderValidationException]
D --> F{Inventory Reserved?}
F -- Yes --> G[Try: Process Payment]
F -- No --> H[Throw InventoryException]
G --> I{Payment Success?}
I -- Yes --> J[Try: Schedule Shipping]
I -- No --> K[Compensation: Release Inventory]
J --> L{Shipping Scheduled?}
L -- Yes --> M[Complete Successfully]
L -- No --> N[Compensation: Refund Payment]
K --> O[Throw PaymentException]
N --> P[Compensation: Release Inventory]
P --> Q[Throw ShippingException]
style A fill:#e1f5fe
style M fill:#e8f5e8
style E fill:#ffebee
style H fill:#ffebee
style O fill:#ffebee
style Q fill:#ffebee
style K fill:#fff3e0
style N fill:#fff3e0
style P fill:#fff3e0
Error Handling Pattern Categories
graph TB
subgraph "Error Handling Patterns"
subgraph "Saga Pattern - Compensation"
R[Success Path: Forward Operations]
S[Failure Path: Compensation Operations]
R --> S
end
subgraph "Circuit Breaker Pattern"
T[Track Consecutive Failures]
U{Failure Count > Threshold?}
U -- Yes --> V[Open Circuit - Fast Fail]
U -- No --> W[Continue Normal Operation]
T --> U
end
subgraph "Exception Hierarchy"
X[BusinessException - Retriable]
Y[CriticalException - Non-Retriable]
Z[ApplicationFailure - Custom]
end
end
style R fill:#e8f5e8
style S fill:#fff3e0
style V fill:#ffebee
style W fill:#e8f5e8
style X fill:#e3f2fd
style Y fill:#ffebee
style Z fill:#f3e5f5
💡 Key Insights from Error Handling
Saga Pattern (Compensation):
- ✅ Forward operations create business value
- ✅ Compensation operations undo changes on failure
- ✅ Order matters - compensate in reverse order
- ✅ Idempotent compensations are safe to retry
Circuit Breaker Pattern:
- ✅ Tracks failure rate of external services
- ✅ Opens circuit when threshold exceeded
- ✅ Fast fails prevent resource waste
- ✅ Automatic recovery when service stabilizes
Exception Classification Strategy
Error Handling Decision Matrix:
| Error Type | Action | Compensation | Recovery |
|---|---|---|---|
| Validation | Fail Fast | None | Fix input |
| Business Rule | Fail Fast | None | Change business logic |
| Resource | Retry | Release | Wait and retry |
| External Service | Circuit Breaker | Rollback | Service recovery |
Smart error classification enables appropriate response strategies
🚀 Production Benefits
This error handling approach provides:
- ✅ Data consistency through compensation patterns
- ✅ System stability via circuit breakers
- ✅ Fast failure detection with custom exceptions
- ✅ Resource protection through smart retry logic
- ✅ Operational visibility with structured error context
Building bulletproof distributed systems! 🎉