Replicate data across your applications
Clone or download
Pull request Compare This branch is 130 commits ahead of promiscuous-io:master.
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.

Promiscuous Gem Version Build Status Code Climate

Promiscuous is a pub-sub framework for easily replicating data across your Ruby applications. Promiscuous guarantees that a subscriber never sees out of order updates and that all updates are eventually replicated.

Benefits over database replication

  • Hetrogenous replication. e.g. replicate from Mongo -> Postgres | ElasticSearch | Redis ...
  • "Remote observers". The ability to observe model changes in one application from another.
  • Publish virtual attributes

Rails Quick Tutorial

1. Preparation

We need a few things for the promiscuous tutorial:

  • The AMQP broker RabbitMQ up and running.
  • The key-value storage system Redis (at least 2.6) up and running.
  • Two Rails applications with the promiscuous gem installed.
  • Both applications must be running on separate databases.
  • Both applications must have a User model (ActiveRecord or Mongoid) with two attributes name and email.

2. Publishing

By including the Promiscuous publisher mixin, we can publish the model attributes:

# app/models/user.rb on the publisher app
class User
  include Promiscuous::Publisher
  publish :name, :email

3. Subscribing

Similarly to the publisher app, we can subscribe to the attributes:

# app/models/user.rb on the subscriber app
class User
  include Promiscuous::Subscriber
  subscribe :name, :email

  after_create { "Hi #{name}!" }

4. Replication

The subscriber must listen for new data to arrive. Promiscuous has a worker that we can launch with the following command:

bundle exec promiscuous subscribe

You should start the subscriber first, otherwise the appropriate queues will not be created. From now on, you should see the queue in the RabbitMQ web admin page. Create a new user in the publisher's Rails console with:

User.create(:name => 'Yoda')`

You should see the message "Hi Yoda!" appearing in the log file of the subscriber.

Promiscuous in Depth

Features and Recipes



Going to Production