Event Driven Architecture Programming in Lisp Part 2

References for our discussion:

• The power of abstraction, reuse and simplicity: an object-oriented library for event-driven design. Most of the code implemented for a EDA is derived from this document.
  
• Graphic Objects. Lisp example for EDA. Specifically Graphic User Interfaces.
• Big, Complex, and Tested? Just Say ‘When’. Ruby example. Follows closely Bertrand Meyer’s document for the implementation of the

Requirements for our EDA:

• Storage of events to be executed when events triggered.
• Events.
• Push/Pull Model.
• Broadcast of events. One trigger can execute more than one handler.
  • Ex. When User Clicks Save Button, data is saved and the event is logged as executed.

Event Driven Architecture Programming in Lisp Part 1

• What is Event Driven Architecture Programming?
  • It is the ability to inform interested objects (consumer/subscriber/sink) of changes of state from other objects (producer/subscriber/source) with events.
• Why use this architecture?
  • There are two reason to use this architecture. One is to loosely couple the interacting objects. The second is that it is best-suited for use in an asynchronous context.
• What are the components required?
  • A table that stores event-handlers
  • An interface to register a trigger of events.
  • An interface to register notification of an event trigger.
  • An interface to trigger events.
• How to represent events?
  • Closures