NATS - Pure Ruby Client

A thread safe Ruby client for the NATS messaging system written in pure Ruby.

Getting Started

gem install nats-pure

Basic Usage

require 'nats/io/client'

nats = NATS::IO::Client.new

nats.connect(:servers => ["nats://127.0.0.1:4222"])
puts "Connected to #{nats.connected_server}"

# Simple subscriber
nats.subscribe("foo.>") { |msg, reply, subject| puts "Received on '#{subject}': '#{msg}'" }

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

# Unsubscribing
sid = nats.subscribe('bar') { |msg| puts "Received : '#{msg}'" }
nats.unsubscribe(sid)

# Requests with a block handles replies asynchronously
nats.request('help', 'please', max: 5) { |response| puts "Got a response: '#{response}'" }

# Replies
nats.subscribe('help') do |msg, reply, subject|
  puts "Received on '#{subject}': '#{msg}'"
  nats.publish(reply, "I'll help!")
end

# Request without a block waits for response or timeout
begin
  msg = nats.request('help', 'please', timeout: 0.5)
  puts "Received on '#{msg.subject}': #{msg.data}"
rescue NATS::IO::Timeout
  puts "nats: request timed out"
end

# Server roundtrip which fails if it does not happen within 500ms
begin
  nats.flush(0.5)
rescue NATS::IO::Timeout
  puts "nats: flush timeout"
end

# Closes connection to NATS
nats.close

Clustered Usage

require 'nats/io/client'

nats = NATS::IO::Client.new

nats.on_error do |e|
  puts "Error: #{e}"
end

nats.on_reconnect do
  puts "Reconnected to server at #{nats.connected_server}"
end

nats.on_disconnect do
  puts "Disconnected!"
end

nats.on_close do
  puts "Connection to NATS closed"
end

cluster_opts = {
  servers: ["nats://127.0.0.1:4222", "nats://127.0.0.1:4223"],
  dont_randomize_servers: true,
  reconnect_time_wait: 0.5,
  max_reconnect_attempts: 2
}

nats.connect(cluster_opts)
puts "Connected to #{nats.connected_server}"

nats.subscribe("hello") do |data|
  puts "#{Time.now} - Received: #{data}"
end

n = 0
loop do
  n += 1
  nats.publish("hello", "world.#{n}")
  sleep 0.1
end

TLS

It is possible to setup a custom TLS connection to NATS by passing an OpenSSL context to the client to be used on connect:

tls_context = OpenSSL::SSL::SSLContext.new
tls_context.ssl_version = :TLSv1_2

nats.connect({
   servers: ['tls://127.0.0.1:4444'],
   reconnect: false,
   tls: {
     context: tls_context
   }
 })

License

(The MIT License)

Copyright (c) 2016 Apcera Inc.

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.