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Design - Behaviour

Component Lifecycle

Component: [Component Name]

Initialization: - [Startup step 1] - [Startup step 2] - [Configuration loading]

Running State: - [Main operation 1] - [Main operation 2] - [Event handling]

Shutdown: - [Graceful shutdown steps] - [Resource cleanup] - [State persistence]

Lifecycle Diagram:

stateDiagram-v2
    [*] --> Initializing
    Initializing --> Running
    Running --> Shutting_Down
    Shutting_Down --> [*]

    Running --> Error: Fault Detected
    Error --> Recovery
    Recovery --> Running

Component: [Component Name]

[Continue with additional components...]

State Management

Stateful Components

Describe components that maintain state:

Component: [Component Name]

State Variables: - state_var1 (type): [Description] - state_var2 (type): [Description]

State Transitions:

stateDiagram-v2
    [*] --> Idle
    Idle --> Processing: Process Command
    Processing --> Idle: Complete
    Processing --> Error: Error
    Error --> Idle: Reset

State Persistence: [How is state saved?]

Stateless Components

Purpose: [These components don't maintain state]

Advantages: [Easier scaling, no coordination needed]

Examples: [Load balancers, API gateways]

Individual Component Behaviors

Component: [Component Name]

Responsibilities: [What does this component do?]

Triggers: [What causes it to act?]

Responses: [What does it do in response?]

State Management: [Stateful or stateless?]

Event Handling:

sequenceDiagram
    participant Env as Environment
    participant Comp as Component

    Env->>Comp: Event 1
    Comp->>Comp: Update State
    Comp->>Env: Response/Side Effect

Error Handling: [How are errors handled?]

Component: [Component Name]

[Continue with additional components...]

System State Updates

Who Updates System State?

Identify which components are responsible for updating each type of state:

State Element Owner Component Update Frequency Update Method
[State 1] [Component] [Frequency] [Method]
[State 2] [Component] [Frequency] [Method]

When and How State is Updated

Synchronous Updates: - [Direct state change on component] - [Immediate consistency]

Asynchronous Updates: - [Event-driven state changes] - [Eventual consistency]

Example State Update Flow:

sequenceDiagram
    participant User
    participant API
    participant Service
    participant StateStore
    participant Cache
    participant Notifier

    User->>API: Update Request
    API->>Service: Process Update
    Service->>StateStore: Write New State
    StateStore->>Cache: Invalidate/Update
    StateStore->>Notifier: Publish Event
    Notifier->>User: Notify Change

Consistency Guarantees

Strong Consistency

Definition: All reads return the latest written value

When Achieved: - [Approach 1] - [Approach 2]

Trade-offs: [Higher latency, reduced availability]

Eventual Consistency

Definition: Replicas eventually converge to same state

Convergence Time: [Expected time to consistency]

Conflict Resolution: [How are conflicts resolved?]

Trade-offs: [Lower latency, temporary inconsistencies]

Causal Consistency

Definition: Related operations respect causal ordering

Implementation: [How is this achieved?]

Component Interaction Patterns

Request-Response Pattern

Flow: 1. Component A sends request to Component B 2. Component B processes request 3. Component B sends response 4. Component A receives response

Example:

sequenceDiagram
    participant A as Comp A
    participant B as Comp B

    A->>+B: Request(data)
    Note over B: Processing
    B-->>-A: Response(result)

Publish-Subscribe Pattern

Flow: 1. Publisher emits event 2. All subscribers receive event 3. Subscribers process independently

Example:

sequenceDiagram
    participant Pub as Publisher
    participant Broker as Message Broker
    participant Sub1 as Subscriber 1
    participant Sub2 as Subscriber 2

    Pub->>Broker: Publish(event)
    Broker->>Sub1: Deliver(event)
    Broker->>Sub2: Deliver(event)
    Sub1->>Sub1: Process
    Sub2->>Sub2: Process

Observer Pattern

Components: [Which components observe which?]

Events Observed: [What events trigger notifications?]

Update Mechanism: [Pull vs Push]

Failure Handling

Component Failure

Detection: [How are failures detected?]

Response: [What happens when a failure is detected?]

Recovery: [How does the component recover?]

stateDiagram-v2
    [*] --> Normal
    Normal --> Detecting_Failure: Failure Occurs
    Detecting_Failure --> Alerting
    Alerting --> Attempting_Recovery
    Attempting_Recovery --> Normal: Success
    Attempting_Recovery --> Degraded: Partial Recovery
    Attempting_Recovery --> Failed: Recovery Failed
    Degraded --> Normal: Full Recovery

Message Failure

Lost Message: [How are lost messages handled?]

Duplicates: [How are duplicate messages handled?]

Out-of-Order: [How are out-of-order messages handled?]