📜 Diagram for Lesson 5: Adding a Simple Activity
Visualizing Workflow-Activity Communication
Core architecture and communication flow between a workflow and its activities
Calculator Workflow Flow
flowchart TD
A[Client starts CalculatorWorkflow] --> B[Workflow receives input: a, b, operation]
B --> C{Workflow validates input}
C -- Valid --> D[Call MathActivity.calculate]
C -- Invalid --> E[Return error result]
D --> F[Activity performs calculation]
F --> G[Activity returns result]
G --> H[Workflow receives result]
H --> I[Workflow returns final result]
subgraph "Worker Process"
subgraph "Workflow Execution"
B
C
H
I
end
subgraph "Activity Execution"
D
F
G
end
end
style A fill:#e1f5fe
style D fill:#f3e5f5
style F fill:#f3e5f5
style I fill:#e8f5e8
Architecture Separation
graph LR
subgraph "Temporal Architecture"
subgraph "Orchestration Layer"
W[CalculatorWorkflow]
W --> |"Coordinates"| O[Orchestration Logic]
end
subgraph "Execution Layer"
A[MathActivity]
A --> |"Executes"| B[Business Logic]
end
W -.->|"Calls via Stub"| A
A -.->|"Returns Result"| W
end
style W fill:#e3f2fd
style A fill:#f3e5f5
style O fill:#e8f5e8
style B fill:#fff3e0
💡 Key Architecture Insights
Fundamental Pattern:
- ✅ Workflows orchestrate - decision making and flow control
- ✅ Activities execute - actual business logic and external calls
- ✅ Clear separation between coordination and execution
- ✅ Deterministic workflows call non-deterministic activities
- ✅ Activity stubs provide type-safe communication
Benefits:
- Testability - Each component can be tested independently
- Scalability - Activities can scale based on workload
- Reliability - Temporal handles retries and failures automatically
Communication Flow Details
Step-by-Step Execution:
- Client starts workflow with input parameters
- Workflow receives parameters and validates them
- Workflow creates activity stub and calls activity
- Activity performs actual calculation work
- Activity returns result to workflow
- Workflow processes result and returns to client
Key Concepts:
- Synchronous calls from workflow perspective
- Asynchronous execution under the hood
- Automatic retry and timeout handling
🚀 Production Benefits
This fundamental pattern provides:
- ✅ Fault tolerance - Automatic retries and error handling
- ✅ Scalability - Workers can be scaled independently
- ✅ Observability - Complete execution history and logging
- ✅ Maintainability - Clear separation of concerns
- ✅ Testability - Components can be mocked and tested
Foundation for all complex Temporal workflows! 🎉