2. Request-Response Flow Diagram

GET /api/traffic/action (Auto-generated observations)

sequenceDiagram
    participant Client as External Client
    participant JG as Java Gateway<br/>Port 8080
    participant PS as Python Service<br/>Port 8000
    participant Model as RL Model<br/>PPO

    Client->>JG: GET /api/traffic/action

    Note over JG: Generate dummy<br/>observations (10 values)
    JG->>JG: Create random observation<br/>values [0-1]

    JG->>PS: POST /predict_action<br/>{"obs_data": [0.1, 0.2, ...]}

    Note over PS: Load model & predict
    PS->>Model: Call model.predict()
    Model-->>PS: Return action (0-3)

    Note over PS: Format response
    PS-->>JG: {"action": 2}

    Note over JG: Map action to signal
    JG->>JG: 2 → "GREEN"

    JG-->>Client: {<br/>"predictedAction": 2,<br/>"signalState": "GREEN",<br/>"timestamp": ...,<br/>"status": "success"<br/>}

POST /api/traffic/action (Custom observations)

sequenceDiagram
    participant Client as External Client
    participant JG as Java Gateway<br/>Port 8080
    participant Val as Validator
    participant PS as Python Service<br/>Port 8000
    participant Model as RL Model<br/>PPO

    Client->>JG: POST /api/traffic/action<br/>{"observations": [0.1, 0.2, ...]}

    JG->>Val: Validate observations
    alt Validation Success
        Val-->>JG: ✓ Valid
    else Validation Failed
        Val-->>JG: ✗ Error: Empty/Null
        JG-->>Client: 400 Bad Request
    end

    JG->>PS: POST /predict_action<br/>{"obs_data": [0.1, 0.2, ...]}

    Note over PS: Process with model
    PS->>Model: Call model.predict()
    Model-->>PS: Return action

    PS-->>JG: {"action": 1}

    JG-->>Client: {<br/>"predictedAction": 1,<br/>"signalState": "YELLOW",<br/>"timestamp": ...,<br/>"status": "success"<br/>}

GET /api/traffic/health (Health Check)

sequenceDiagram
    participant Client as External Client
    participant JG as Java Gateway<br/>Port 8080
    participant HealthCheck as Health Checker
    participant PS as Python Service<br/>Port 8000

    Client->>JG: GET /api/traffic/health

    JG->>HealthCheck: Check all services

    HealthCheck->>PS: GET /health

    alt Python Service "Up"
        PS-->>HealthCheck: {"status": "healthy"}
        HealthCheck-->>JG: ✓ All healthy
    else Python Service "Down"
        PS--xHealthCheck: Connection refused
        HealthCheck-->>JG: ⚠️ Degraded
    end

    JG-->>Client: {<br/>"status": "healthy",<br/>"inferenceService": "up",<br/>"timestamp": ...<br/>}