Super simple event system built on top of ActiveJob.

KittyEvents implements the publish/subscribe pattern using ActiveJob. You setup your events and list the subscribers for them. When an event is triggered, KittyEvents will fanout the event to each of your subscribers.

• Uses ActiveJob. No need to add a new dependency for pub/sub.
• Reduce complexity/establish patterns. Can be used to replace after_commit's. This creates easier to follow/read code. Less surprises = good!
• Replace several perform_later's with a single event trigger. Reducing the amount of I/O happening in request (less I/O = faster response times)

Add this line to your application's Gemfile:

gem 'kitty_events'

And then execute:

$ bundle install

In Rails, setup your events and subscribers.

module ApplicationEvents
  extend KittyEvents

  event :user_signup, [
    WelcomeEmailWorker,
    WelcomeTweetWorker,
    SyncProfileImageWorker,
    ExampleWorker.set(wait: 5.minutes), # standard ActiveJob settings work as well!
  ]

  event :user_upvote, [
    SomeWorker,
    AnotherWorker,
  ]
end

You can put this in app/workers or similar folder.

Each subscriber must be an ActiveJob and respond to perform_later(object).

class ExampleWorker < ActiveJob::Base
  def perform(user)
    # do work
  end
end

Then in your application, to trigger an event. Do the following.

ApplicationEvents.trigger(:user_signup, user)

Using the above example, triggering this event would pass user to each of the subscribers defined in our initializer:

WelcomeEmailWorker,
WelcomeTweetWorker,
SyncProfileImageWorker,
ExampleWorker.set(wait: 5.minutes)

The worker is configurable via the initializer. Here are examples for catching errors and setting the queue.

# config/initializers/application_events.rb
module ApplicationEvents
  extend KittyEvents

  event :user_signup, [
    WelcomeEmailWorker,
    WelcomeTweetWorker,
  ]

  handle_worker.rescue_from ActiveJob::DeserializationError do |exception|
    # handle deserialization errors
  end

  handle_worker.queue_as :events # use a specific queue
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/producthunt/kittyevents. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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