LowEvent

LowEvent is a framework for event-driven applications where events are present-tense, not past-tense.

Events

LowEvent represents events of all kinds; RequestEvent, RouteEvent, RenderEvent and ResponseEvent.

Inherit from LowEvent to create your own event:

class MyEvent < LowEvent
  def initialize(data:, action: :render)
    super(key: self.class, action:)
    @data = data
  end
end

Observers

Observe the event with:

class MyObserver
  include Observers
  observe MyEvent

  def render(event:)
    event.data
  end
end

Trigger the event's action on its observers with:

MyEvent.trigger(data: "Custom Data")

ℹ️ For more info see Observers.

Architecture

A LowEvent is primarily concerned with what is happening, not what has happened.

Comparison

An Event-Command Hybrid:

	Event	LowEvent	Command
Tense	Past	Past/Present/Future	Future
Naming	OrderCreated	OrderEvent	CreateOrder
Action	🚫	:create_order	✅
Mutability	Immutable	Mutable/Immutable	Immutable
State		Ordered Actions	🚫
Broadcasting	One to many	Ordered one to many	One to one
Return value	🚫	Value or nil	Value

Event Tree

LowEvent builds a tree of every event as it's occuring and every subsequent event that occurs because of that event:

Installation

Add gem 'low_event' to your Gemfile then:

bundle install