NatsStreamingListener

This gem implements functionality of nats-listener with nats streaming.

Installation

Add this line to your application's Gemfile:

gem 'nats_streaming_listener'

And then execute:

$ bundle

Or install it yourself as:

$ gem install nats_streaming_listener

Usage

Creating client

NatsStreamingListener::Client.current = NatsStreamingListener::Client.new(
  logger: Ougai::Logger.new(STDOUT),
  skip: false,
  catch_errors: true,
  catch_provider: Rollbar
)

All arguments are optional. logger - logger that you can pass to application. It will be called to debug messages. skip - skip calls. Useful for tests catch_errors - catch errors, log them and pass to catch_provider catch_provider - provider that is called when error occurs, e.g. Rollbar.

Establishing connection

NatsListener::Client.current.establish_connection(
    service_name: [YOUR SERVICE NAME], 
    nats: { servers: [NATS_SERVERS_URLS] }, # Options passed to nats connector
    cluster_name: [YOUR_CLUSTER_NAME], # Cluster of nats-streaming that you're connecting to
    client_id: [CLIENT_ID] # Id of a client(nats-streaming works with unique client_id)
)

Subscribers

For using subscribers we offer one quite simple way:

1. Create subscribers folder.
2. Create your own subscriber derived from NatsStreamingListener::Subscriber
3. Load and subscribe all subscribers, e.g.

path = Rails.root.join('app', 'subscribers', '*.rb')

Dir.glob(path) do |entry|
  entry.split('/').last.split('.').first.camelize.constantize.new.subscribe
end

Protobuf strategy

By default all nats-streaming messages are processed with protobuf. But if you want - you can use our own small wrapper that handles some info and pass it into nats-streaming.

2.3.3 :006 > require 'nats_streaming_listener'
=> true
2.3.3 :006 > m = NatsStreaming::NatsMessage.new(sender_service_name: 'ololo', receiver_action_name: 'ololo1', receiver_action_parameters:[1,2,3].map(&:to_s), message_timestamp: Time.now.utc.to_i, transaction_id: 'unique')
 => #<NatsListener::NatsMessage sender_service_name="ololo" receiver_action_name="ololo1" receiver_action_parameters=["1", "2", "3"] message_timestamp=1538902717 transaction_id="unique"> 
2.3.3 :007 > m.serialize
 => "\n\x05ololo\x12\x06ololo1\x1A\x011\x1A\x012\x1A\x013 \xBD\x95\xE7\xDD\x05*\x06unique" 

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/[USERNAME]/nats_streaming_listener. 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 NatsStreamingListener project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.