PubSub

PubSub is a thin wrapper around ActiveSupport::Notifications, which provides an implementation of the Publish/Subscribe pattern.

http://api.rubyonrails.org/classes/ActiveSupport/Notifications.html

The goal was to be able to create more loosly coupled models by pulling side effects of our models into their own class. We wanted this behavior for Active Record classes as well as non-Active Record classes.

The result was a library that was:

  • easy to test
  • easy to disable (when using the console, during unit tests, etc.)
  • easy to understand (b/c of AS::Notifications syncronous publishing queue)

Installation

Add this line to your application's Gemfile:

gem 'pub_sub'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pub_sub

Usage

Configuration

PubSub.disable # disables publishing
PubSub.enable  # enables publishing

By default, PubSub looks for subscribers in app/models/pub_sub/*

Within a plain ruby project

PubSub::Subscriber => provides an interface to subscribe to a topic

#
# Subscribe to the 'user_created' topic.
#
class SendWelcomeEmailToUser < PubSub::Subscriber
  subscribe_to("user_created")

  def on_publish
    write_user_to_file(options[:user])
  end

  private

  def write_user_to_file(user)
    File.open("/tmp/users.txt", "w+") do |file|
      file << user.name
    end
  end
end


#
# Publish a message to the 'user_created' topic
#
PubSub.publish("user_created", user:
  User.new(name: 'John Doe')
)

Within a Rails project

PubSub::ActiveRecord::Subscriber => provide an interface to subscribe to an ActiveRecord callback topic

#
# Subscribe to the after_create callback of User
#
# currently, PubSub loads all subscribers in app/models/pub_sub/*
#
class SendWelcomeEmailToUser < PubSub::ActiveRecord::Subscriber
  subscribe_to(User, 'after_create')

  def on_publish
    ApplicationMailer.send_welcome_email(record)
  end
end
=> PubSub.subscribe("active_record::user::after_create")


#
#  inside your application (controller, model, etc)
#
User.create(name: 'John Doe')
=> PubSub.publish("active_record::user::after_create")

Backlog / To Do

http://www.pivotaltracker.com/projects/705655

Feel free to take a look.

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request

Contributors

  • Brent Wheeldon
  • Cathy O'Connell
  • Nick Monje
  • Evan Goodberry
  • Ben Moss
  • Chien Kuo
  • Edwin Chong
  • Adam Berlin
  • Rasheed Abdul-Aziz
  • Ryan McGarvey
  • Geoffrey Ducharme
  • Alex Kramer