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Reactive / Event-driven Structural Styles

✅ Overview​

This family deals with styles that handle structures reacting asynchronously centered on the flow of events and messages.

  • Main design object is "when and how" to react to input.
  • Structure assumes threads, callbacks, event loops, message queues, etc.
  • Important in concurrency, high throughput, and reactive systems.

Representative Styles:

✅ Why This Family Emerged (History & Background)​

  • Importance of concurrency/parallelism with increasing CPU cores.
  • Explosive increase in connections/events due to Web / Mobile / IoT.
  • Blocking I/O models became difficult to scale.
  • High responsiveness and fault tolerance became required.

Reactive / Event-driven styles developed from the need:

"Want to handle concurrency as a flow of events or messages, rather than managing threads directly."

✅ Problems Addressed​

  • Low-level thread management (Lock / Mutex hell).
  • Throughput limits due to synchronous I/O.
  • Difficulty in recovery from abnormalities and fault tolerance design.

Reactive family considers the design of the entire system from perspectives like:

  • "Flow of events (messages)"
  • "Combination of asynchronous processing"
  • "Reactive responsiveness"

✅ Styles Belonging to This Family​

  • Actor Model: Concurrency model where actors communicate with messages.
  • Event Loop based structure: Structure handling asynchronous I/O with a single event loop (Node.js etc.).
  • Reactive Streams: Standardized model including asynchronous stream processing and backpressure.

✅ Relationship with Other Families​

✅ When to Reference​

  • Services requiring high throughput and low latency.
  • Servers handling many clients or connections (Chat / Game / IoT etc.).
  • Systems with event-driven business logic.

Understanding this family gives you the perspective of capturing architecture on the axis of 'What happens when, and how to react to it'.