NATS

A lightweight EventMachine based publish-subscribe messaging system.

Supported Platforms

This gem currently works on the following Ruby platforms:

• MRI 1.8 and 1.9 (Performance is best on 1.9.2)
• Rubinius
• JRuby

Getting Started

[sudo] gem install nats
 == or ==
[sudo] rake geminstall

nats-sub foo &
nats-pub foo 'Hello World!'

Usage

require "nats/client"

NATS.start do

  # Simple Subscriber
  NATS.subscribe('foo') { |msg| puts "Msg received : '#{msg}'" }

  # Simple Publisher
  NATS.publish('foo.bar.baz', 'Hello World!')

  # Unsubscribing
  sid = NATS.subscribe('bar') { |msg| puts "Msg received : '#{msg}'" }
  NATS.unsubscribe(sid)

  # Requests
  NATS.request('help') { |response| puts "Got a response: '#{response}'" }

  # Replies
  NATS.subscribe('help') { |msg, reply| NATS.publish(reply, "I'll help!") }

  # Stop using NATS.stop, exits EM loop if NATS.start started the loop
  NATS.stop

end

Wildcard Subscriptions

  # '*" matches any token, at any level of the subject.
  NATS.subscribe('foo.*.baz') { |msg, reply, sub| puts "Msg received on [#{sub}] : '#{msg}'" }
  NATS.subscribe('foo.bar.*') { |msg, reply, sub| puts "Msg received on [#{sub}] : '#{msg}'" }
  NATS.subscribe('*.bar.*') { |msg, reply, sub| puts "Msg received on [#{sub}] : '#{msg}'" }

  # '>" matches any length of the tail of a subject and can only be last token
  # E.g. 'foo.>' will match 'foo.bar', 'foo.bar.baz', 'foo.foo.bar.bax.22'
  NATS.subscribe('foo.>') { |msg, reply, sub| puts "Msg received on [#{sub}] : '#{msg}'" }

Queues Groups

  # All subscriptions with the same queue name will form a queue group
  # Each message will be delivered to only one subscriber per queue group, queuing semantics
  # You can have as many queue groups as you wish
  # Normal subscribers will continue to work as expected.
  NATS.subscribe(subject, :queue => 'job.workers') { |msg| puts "Received '#{msg}'" }

Advanced Usage

  # Publish with closure, callback fires when server has processed the message
  NATS.publish('foo', 'You done?') { puts 'msg processed!' }

  # Timeouts for subscriptions
  sid = NATS.subscribe('foo') { received += 1 }
  NATS.timeout(sid, TIMEOUT_IN_SECS) { timeout_recvd = true }

  # Timeout unless a certain number of messages have been received
  NATS.timeout(sid, TIMEOUT_IN_SECS, :expected => 2) { timeout_recvd = true }

  # Auto-unsubscribe after MAX_WANTED messages received
  NATS.unsubscribe(sid, MAX_WANTED)

  # Multiple connections
  NATS.subscribe('test') do |msg|
    puts "received msg"
    NATS.stop
  end

  # Form second connection to send message on
  NATS.connect { NATS.publish('test', 'Hello World!') }

See examples and benchmark for more information..

License

(The MIT License)

Copyright (c) 2010, 2011 Derek Collison

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.