jstreams

A distributed streaming platform for Ruby built on top of Redis Streams.

Provides a multi-threaded publisher/subscriber.

Project Status

This is alpha software and not suitable for production use.

Features

• Load balancing among subscribers within a group
• Automatically message reassignment when consumers go away
• Multi-threaded subscribers
• Configurable message serialization

Roadmap

• Configurable retry logic
• Replay a stream from a given point
• Wildcard subscriptions

Installation

Add this line to your application's Gemfile:

gem 'jstreams'

And then execute:

$ bundle

Or install it yourself as:

$ gem install jstreams

Usage

Publisher

jstreams = Jstreams::Context.new

jstreams.publish(
  :users,
  event: 'user_created',
  user_id: 1,
  name: 'King Buzzo',
  email: 'buzzo@example.com'
)

jstreams.publish(:users, event: 'user_logged_in', user_id: 1)

Subscriber

jstreams = Jstreams::Context.new

jstreams.subscribe(
  :user_activity_logger,
  :users
) do |message, _stream, _subscriber|
  case message['event']
  when 'user_created'
    logger.info "User #{message['name']} created"
  when 'user_logged_in'
    logger.info "User #{message['id']} logged in"
  end
end

jstreams.subscribe(
  :send_welcome_email,
  :users
) do |message, _stream, _subscriber|
  send_user_welcome_email(message['id']) if message['event'] == 'user_created'
end

# Spawns subscriber threads and blocks
jstreams.run

Replay

Starts a temporary copy of the given subscriber until messages have been replayed up to the checkpoint stored at the time replay is called.

jstreams.replay(:user_activity_logger, from: message_id)

Retries

By default subscribers will process messages indefinitely until successful.

# TODO

Serialization

class Serializer
  MESSAGE_TYPES = {
    user_created: UserCreatedMessage, user_logged_in: UserLoggedInMessage
  }

  def serialize(type, message)
    message_class(type).serialize(message)
  end

  def deserialize(type, message)
    message_class(type).deserialize(message)
  end

  private

  def message_class(type)
    MESSAGE_TYPES.fetch(type) { raise "Unknown message type: #{type}" }
  end
end

jstreams = Jstreams::Context.new(serializer: Serializer)

Development

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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/jstotz/jstreams. 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.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the jstreams project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.