basic-usage.rb

# Copyright 2016-2018 The NATS Authors
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

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)

# Subscribers which reply to requests
nats.subscribe('help') do |msg, reply, subject|
  puts "[Received] on '#{subject}' #{reply}: '#{msg}'"
  nats.publish(reply, "I'll help!") if reply
end

nats.subscribe('>') do |msg, reply, subject|
  puts "[Received] via wildcard on '#{subject}' #{reply}: '#{msg}'"
  nats.publish(reply, "Hi") if reply
end

# Requests happens asynchronously if given a callback
nats.request('help', 'world', max: 2) do |response|
  puts "[Response] '#{response}'"
end

# Request without a callback waits for the response or times out.
begin
  msg = nats.request('help', 'please', timeout: 1.0)
  puts "[Response] '#{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