Event Handler

An Event Handler is a software component that responds to event notifications with specific actions within event-driven systems.

• Context:
  • It can typically register for Event Notifications from event sources through event registration mechanisms.
  • It can typically execute Handler Logic in response to specific event types.
  • It can typically perform Predefined Actions when event conditions are met.
  • It can typically access Event Data from event objects for action determination.
  • It can typically implement Event Response Strategy based on event type and event context.
  • ...
  • It can often support Multiple Event Types through event type discrimination.
  • It can often maintain Handler Configuration to customize event response behavior.
  • It can often integrate with Application Framework through event handling interfaces.
  • It can often implement Error Management Strategy for event handling failures.
  • It can often provide Callback Execution on event occurrence.
  • ...
  • It can range from being a Simple Event Handler to being a Complex Event Handler, depending on its event handler implementation complexity.
  • It can range from being a Specialized Event Handler to being a General-Purpose Event Handler, depending on its event handler scope.
  • It can range from being a Synchronous Event Handler to being an Asynchronous Event Handler, depending on its event handler execution model.
  • It can range from being a Stateless Event Handler to being a Stateful Event Handler, depending on its event handler state management.
  • ...
  • It can integrate with Event Source for event subscription.
  • It can connect to External System for action execution.
  • It can utilize Monitoring Framework for handler performance measurement.
  • ...
• Examples:
  • Event Handler Types, such as:
    • Execution Model-Based Event Handlers, such as:
      • Synchronous Event Handler executing in the same thread as the event source.
      • Async Event Handler processing event notifications using non-blocking execution patterns.
      • Thread Pool Event Handler delegating event handling to worker threads.
    • Architecture-Specific Event Handlers, such as:
      • UI Event Handler responding to user interaction events in graphical interfaces.
      • Network Event Handler managing socket events in networked applications.
      • System Event Handler responding to operating system events.
    • Implementation Pattern-Based Event Handlers, such as:
      • Callback-Based Event Handler using function references for event response.
      • Observer Pattern Event Handler implementing the observer design pattern.
      • Reactive Event Handler utilizing reactive programming paradigm.
  • ...
• Counter-Examples:
  • Event Processor, which focuses on event transformation and event processing pipelines rather than specific action responses.
  • Polling Mechanism, which actively checks for state changes rather than responding to event notifications.
  • Batch Processor, which processes data sets at scheduled intervals rather than in response to individual events.
  • Request Handler, which specifically processes client requests rather than general event notifications.
• See: Event-Driven Architecture, Observer Pattern, Event Loop, Event Source, Event Bus, Event Processor.

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