Event Handler Pattern

A Event Handler Pattern is a software design pattern that implements the low-level event processing mechanisms within event-driven architectures through defined event handlers.

• Context:
  • It can (typically) manage event detection through event loops.
  • It can (typically) process events using event handlers.
  • It can (typically) maintain event state for process tracking.
  • It can (typically) support event propagation through handler chains.
  • It can (often) implement event filtering for event selection.
  • It can (often) provide event queuing for load management.
  • It can (often) handle concurrent events through parallel processing.
  • ...
  • It can range from being a Simple Event Handler to being a Complex Event Processor, depending on its processing requirements.
  • It can range from being a Synchronous Handler to being an Asynchronous Handler, depending on its execution model.
  • ...
  • It can be implemented using Event Frameworks, such as:
    • Event Emitter for node applications.
    • Event Dispatcher for java applications.
    • Event Bus for distributed systems.
  • ...
• Example(s):
  • Event Handling Architectures, such as:
    • Observer Patterns, such as:
      • DOM Event System for browser events.
      • Message Queue for distributed events.
      • Event Stream for real-time data.
    • Reactor Patterns, such as:
      • Event Loop for io operations.
      • Event Dispatcher for request handling.
      • Event Demultiplexer for concurrent processing.
    • Publisher-Subscriber Patterns, such as:
      • Message Broker for event distribution.
      • Event Bus for system integration.
      • Notification System for user alerts.
  • Event Handler Types, such as:
    • System Event Handlers, such as:
      • IO Event Handler for file operations.
      • Network Event Handler for socket communication.
      • Timer Event Handler for scheduled tasks.
    • Application Event Handlers, such as:
      • UI Event Handler for user interactions.
      • Business Event Handler for domain logic.
      • Integration Event Handler for service communication.
  • ...
• Counter-Example(s):
  • Polling Pattern, which actively checks for state changes.
  • Request-Response Pattern, which follows synchronous flows.
  • Pipeline Pattern, which processes sequential operations.
  • Batch Processing Pattern, which handles grouped operations.
• See: Software Pattern, Event-Driven Architecture, Message Pattern, Asynchronous Programming.

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