Centrifugo HTTP API client in Ruby.

Installation

Add this line to your application's Gemfile:

gem 'cent' 

And then execute:

$ bundle

Or install it yourself as:

$ gem install cent

Usage

Functionality is split between two classes:

• Cent::Client to call API methods
• Cent::Notary to generate tokens

Token Generation

notary = Cent::Notary.new(secret: 'secret')

By default it uses HS256 to generate tokens, but you can set it to one of the HMAC, RSA or ECDSA family.

RSA

secret = OpenSSL::PKey::RSA.new(File.read('./rsa_secret.pem'))
notary = Cent::Notary.new(secret: secret, algorithm: 'RS256')

ECDSA

secret = OpenSSL::PKey::EC.new(File.read('./ecdsa_secret.pem'))
notary = Cent::Notary.new(secret: secret, algorithm: 'ES256')

Connection token

When connecting to Centrifugo client must provide connection JWT token with several predefined credential claims.

notary.issue_connection_token(sub: '42') 

#=> "eyJhbGciOiJIUzI1NiJ9..."

info and exp are supported as well:

notary.issue_connection_token(sub: '42', info: { scope: 'admin' }, exp: 1629050099) 

#=> "eyJhbGciOiJIUzI1NiJ9..."

Private channel token

All channels starting with $ considered private and require a channel token to subscribe. Private channel subscription token is also JWT(see the claims)

notary.issue_channel_token(sub: '42', channel: 'channel', exp: 1629050099, info: { scope: 'admin' }) 

#=> "eyJhbGciOiJIUzI1NiJ9..."

API Client

A client requires your Centrifugo API key to execute all requests.

client = Cent::Client.new(api_key: 'key')

you can customize your connection as you wish, just remember it's a Faraday::Connection instance:

client = Cent::Client.new(api_key: 'key', endpoint: 'https://centrifu.go/api') do |connection|
  connection.headers['User-Agent'] = 'Centrifugo Ruby Client'
  connection.options.open_timeout = 3
  connection.options.timeout = 7
  connection.adapter :typhoeus
end

Publish

Send data to the channel.

publish

client.publish(channel: 'chat', data: 'hello') # => {}

Broadcast

Sends data to multiple channels.

broadcast

client.broadcast(channels: ["clients", "staff"], data: 'hello') # => {}

Unsubscribe

Unsubscribe user from channel. Receives to arguments: channel and user (user ID you want to unsubscribe)

unsubscribe

client.unsubscribe(channel: 'chat', user: '1') # => {}

Disconnect

Allows to disconnect user by it's ID. Receives user ID as an argument.

disconnect

# Disconnect user with `id = 1`
# 
client.disconnect(user: '1') # => {}

Presence

Get channel presence information(all clients currently subscribed on this channel).

presence

client.presence(channel: 'chat') 

# {
#   'result' => {
#     'presence' => {
#       'c54313b2-0442-499a-a70c-051f8588020f' => {
#         'client' => 'c54313b2-0442-499a-a70c-051f8588020f',
#         'user' => '42'
#       },
#       'adad13b1-0442-499a-a70c-051f858802da' => {
#         'client' => 'adad13b1-0442-499a-a70c-051f858802da',
#         'user' => '42'
#       }
#     }
#   }
# }

Presence stats

Get short channel presence information.

presence_stats

client.presence_stats(channel: 'chat')

# {
#   "result" => {
#     "num_clients" => 0,
#     "num_users" => 0
#   }
# }

History

Get channel history information (list of last messages published into channel).

history

client.history(channel: 'chat') 

# {
#   'result' => {
#     'publications' => [
#       {
#         'data' => {
#           'text' => 'hello'
#         }
#       },
#       {
#         'data' => {
#           'text' => 'hi!'
#         }
#       }
#     ]
#   }
# }

Channels

Get list of active(with one or more subscribers) channels.

channels

client.channels

# {
#   'result' => {
#     'channels' => [
#       'chat'
#     ]
#   }
# }

Info

Get running Centrifugo nodes information.

info

client.info

# {
#   'result' => {
#     'nodes' => [
#       {
#         'name' => 'Alexanders-MacBook-Pro.local_8000',
#         'num_channels' => 0,
#         'num_clients' => 0,
#         'num_users' => 0,
#         'uid' => 'f844a2ed-5edf-4815-b83c-271974003db9',
#         'uptime' => 0,
#         'version' => ''
#       }
#     ]
#   }
# }

Errors

Network errors are not wrapped and will raise Faraday::ClientError.

In cases when Centrifugo returns 200 with error key in the body we wrap it and return custom error:

# Raised when response from Centrifugo contains any error as result of API command execution.
#
begin
  client.publish(channel: 'channel', data: { foo: :bar })
rescue Cent::ResponseError => ex
  ex.message # => "Invalid format"
end

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/centrifugal/rubycent. 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.