Class: MQTT::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/mqtt/client.rb

Overview

Client class for talking to an MQTT server

Constant Summary collapse

SELECT_TIMEOUT =

Timeout between select polls (in seconds)

0.5
ATTR_DEFAULTS =

Default attribute values

{
  :host => nil,
  :port => nil,
  :version => '3.1.1',
  :keep_alive => 15,
  :clean_session => true,
  :client_id => nil,
  :ack_timeout => 5,
  :username => nil,
  :password => nil,
  :will_topic => nil,
  :will_payload => nil,
  :will_qos => 0,
  :will_retain => false,
  :ssl => false
}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Client

Create a new MQTT Client instance

Accepts one of the following:

  • a URI that uses the MQTT scheme

  • a hostname and port

  • a Hash containing attributes to be set on the new instance

If no arguments are given then the method will look for a URI in the MQTT_SERVER environment variable.

Examples:

client = MQTT::Client.new
client = MQTT::Client.new('mqtt://myserver.example.com')
client = MQTT::Client.new('mqtt://user:pass@myserver.example.com')
client = MQTT::Client.new('myserver.example.com')
client = MQTT::Client.new('myserver.example.com', 18830)
client = MQTT::Client.new(:host => 'myserver.example.com')
client = MQTT::Client.new(:host => 'myserver.example.com', :keep_alive => 30)


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# File 'lib/mqtt/client.rb', line 134

def initialize(*args)
  if args.last.is_a?(Hash)
    attr = args.pop
  else
    attr = {}
  end

  if args.length == 0
    if ENV['MQTT_SERVER']
      attr.merge!(parse_uri(ENV['MQTT_SERVER']))
    end
  end

  if args.length >= 1
    case args[0]
      when URI
        attr.merge!(parse_uri(args[0]))
      when %r|^mqtts?://|
        attr.merge!(parse_uri(args[0]))
      else
        attr.merge!(:host => args[0])
    end
  end

  if args.length >= 2
    attr.merge!(:port => args[1]) unless args[1].nil?
  end

  if args.length >= 3
    raise ArgumentError, "Unsupported number of arguments"
  end

  # Merge arguments with default values for attributes
  ATTR_DEFAULTS.merge(attr).each_pair do |k,v|
    self.send("#{k}=", v)
  end

  # Set a default port number
  if @port.nil?
    @port = @ssl ? MQTT::DEFAULT_SSL_PORT : MQTT::DEFAULT_PORT
  end

  # Initialise private instance variables
  @last_ping_request = Time.now
  @last_ping_response = Time.now
  @socket = nil
  @read_queue = Queue.new
  @pubacks = {}
  @read_thread = nil
  @write_semaphore = Mutex.new
  @pubacks_semaphore = Mutex.new
end

Instance Attribute Details

#ack_timeoutObject

Number of seconds to wait for acknowledgement packets (default is 5 seconds)



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# File 'lib/mqtt/client.rb', line 36

def ack_timeout
  @ack_timeout
end

#clean_sessionObject

Set the 'Clean Session' flag when connecting? (default is true)



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# File 'lib/mqtt/client.rb', line 30

def clean_session
  @clean_session
end

#client_idObject

Client Identifier



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# File 'lib/mqtt/client.rb', line 33

def client_id
  @client_id
end

#hostObject

Hostname of the remote server



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# File 'lib/mqtt/client.rb', line 8

def host
  @host
end

#keep_aliveObject

Time (in seconds) between pings to remote server (default is 15 seconds)



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# File 'lib/mqtt/client.rb', line 27

def keep_alive
  @keep_alive
end

#last_ping_responseObject (readonly)

Last ping response time



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# File 'lib/mqtt/client.rb', line 57

def last_ping_response
  @last_ping_response
end

#passwordObject

Password to authenticate to the server with



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# File 'lib/mqtt/client.rb', line 42

def password
  @password
end

#portObject

Port number of the remote server



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# File 'lib/mqtt/client.rb', line 11

def port
  @port
end

#sslObject

Set to true to enable SSL/TLS encrypted communication

Set to a symbol to use a specific variant of SSL/TLS. Allowed values include:

Examples:

Using TLS 1.0

client = Client.new('mqtt.example.com', :ssl => :TLSv1)

See Also:

  • OpenSSL::SSL::SSLContext::METHODS


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# File 'lib/mqtt/client.rb', line 24

def ssl
  @ssl
end

#usernameObject

Username to authenticate to the server with



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# File 'lib/mqtt/client.rb', line 39

def username
  @username
end

#versionObject

The version number of the MQTT protocol to use (default 3.1.1)



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# File 'lib/mqtt/client.rb', line 14

def version
  @version
end

#will_payloadObject

Contents of message that is sent by server when client disconnect



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# File 'lib/mqtt/client.rb', line 48

def will_payload
  @will_payload
end

#will_qosObject

The QoS level of the will message sent by the server



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# File 'lib/mqtt/client.rb', line 51

def will_qos
  @will_qos
end

#will_retainObject

If the Will message should be retain by the server after it is sent



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# File 'lib/mqtt/client.rb', line 54

def will_retain
  @will_retain
end

#will_topicObject

The topic that the Will message is published to



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# File 'lib/mqtt/client.rb', line 45

def will_topic
  @will_topic
end

Class Method Details

.connect(*args, &block) ⇒ Object

Create and connect a new MQTT Client

Accepts the same arguments as creating a new client. If a block is given, then it will be executed before disconnecting again.

Example:

MQTT::Client.connect('myserver.example.com') do |client|
  # do stuff here
end


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# File 'lib/mqtt/client.rb', line 91

def self.connect(*args, &block)
  client = MQTT::Client.new(*args)
  client.connect(&block)
  return client
end

.generate_client_id(prefix = 'ruby', length = 16) ⇒ Object

Generate a random client identifier (using the characters 0-9 and a-z)



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# File 'lib/mqtt/client.rb', line 99

def self.generate_client_id(prefix='ruby', length=16)
  str = prefix.dup
  length.times do
    num = rand(36)
    if (num<10)
      # Number
      num += 48
    else
      # Letter
      num += 87
    end
    str += num.chr
  end
  return str
end

Instance Method Details

#ca_file=(path) ⇒ Object

Set a path to a file containing a PEM-format CA certificate and enable peer verification



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# File 'lib/mqtt/client.rb', line 215

def ca_file=(path)
  ssl_context.ca_file = path
  unless path.nil?
    ssl_context.verify_mode = OpenSSL::SSL::VERIFY_PEER
  end
end

#cert=(cert) ⇒ Object

PEM-format client certificate



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# File 'lib/mqtt/client.rb', line 198

def cert=(cert)
  ssl_context.cert = OpenSSL::X509::Certificate.new(cert)
end

#cert_file=(path) ⇒ Object

Set a path to a file containing a PEM-format client certificate



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# File 'lib/mqtt/client.rb', line 193

def cert_file=(path)
  self.cert = File.read(path)
end

#connect(clientid = nil) ⇒ Object

Connect to the MQTT server If a block is given, then yield to that block and then disconnect again.



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# File 'lib/mqtt/client.rb', line 235

def connect(clientid=nil)
  unless clientid.nil?
    @client_id = clientid
  end

  if @client_id.nil? or @client_id.empty?
    if @clean_session
      if @version == '3.1.0'
        # Empty client id is not allowed for version 3.1.0
        @client_id = MQTT::Client.generate_client_id
      end
    else
      raise 'Must provide a client_id if clean_session is set to false'
    end
  end

  if @host.nil?
    raise 'No MQTT server host set when attempting to connect'
  end

  if not connected?
    # Create network socket
    tcp_socket = TCPSocket.new(@host, @port)

    if @ssl
      # Set the protocol version
      if @ssl.is_a?(Symbol)
        ssl_context.ssl_version = @ssl
      end

      @socket = OpenSSL::SSL::SSLSocket.new(tcp_socket, ssl_context)
      @socket.sync_close = true

      # Set hostname on secure socket for Server Name Indication (SNI)
      if @socket.respond_to?(:hostname=)
        @socket.hostname = @host
      end

      @socket.connect
    else
      @socket = tcp_socket
    end

    # Construct a connect packet
    packet = MQTT::Packet::Connect.new(
      :version => @version,
      :clean_session => @clean_session,
      :keep_alive => @keep_alive,
      :client_id => @client_id,
      :username => @username,
      :password => @password,
      :will_topic => @will_topic,
      :will_payload => @will_payload,
      :will_qos => @will_qos,
      :will_retain => @will_retain
    )

    # Send packet
    send_packet(packet)

    # Receive response
    receive_connack

    # Start packet reading thread
    @read_thread = Thread.new(Thread.current) do |parent|
      Thread.current[:parent] = parent
      while connected? do
        receive_packet
      end
    end
  end

  # If a block is given, then yield and disconnect
  if block_given?
    begin
      yield(self)
    ensure
      disconnect
    end
  end
end

#connected?Boolean

Checks whether the client is connected to the server.

Returns:

  • (Boolean)


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# File 'lib/mqtt/client.rb', line 336

def connected?
  (not @socket.nil?) and (not @socket.closed?)
end

#disconnect(send_msg = true) ⇒ Object

Disconnect from the MQTT server. If you don't want to say goodbye to the server, set send_msg to false.



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# File 'lib/mqtt/client.rb', line 319

def disconnect(send_msg=true)
  # Stop reading packets from the socket first
  @read_thread.kill if @read_thread and @read_thread.alive?
  @read_thread = nil

  # Close the socket if it is open
  if connected?
    if send_msg
      packet = MQTT::Packet::Disconnect.new
      send_packet(packet)
    end
    @socket.close unless @socket.nil?
    @socket = nil
  end
end

#get(topic = nil, options = {}) ⇒ Object

Return the next message received from the MQTT server. An optional topic can be given to subscribe to.

The method either returns the topic and message as an array:

topic,message = client.get

Or can be used with a block to keep processing messages:

client.get('test') do |topic,payload|
  # Do stuff here
end


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# File 'lib/mqtt/client.rb', line 402

def get(topic=nil, options={})
  if block_given?
    get_packet(topic) do |packet|
      yield(packet.topic, packet.payload) unless packet.retain && options[:omit_retained]
    end
  else
    loop do
      # Wait for one packet to be available
      packet = get_packet(topic)
      return packet.topic, packet.payload unless packet.retain && options[:omit_retained]
    end
  end
end

#get_packet(topic = nil) ⇒ Object

Return the next packet object received from the MQTT server. An optional topic can be given to subscribe to.

The method either returns a single packet:

packet = client.get_packet
puts packet.topic

Or can be used with a block to keep processing messages:

client.get_packet('test') do |packet|
  # Do stuff here
  puts packet.topic
end


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# File 'lib/mqtt/client.rb', line 429

def get_packet(topic=nil)
  # Subscribe to a topic, if an argument is given
  subscribe(topic) unless topic.nil?

  if block_given?
    # Loop forever!
    loop do
      packet = @read_queue.pop
      yield(packet)
      puback_packet(packet) if packet.qos > 0
    end
  else
    # Wait for one packet to be available
    packet = @read_queue.pop
    puback_packet(packet) if packet.qos > 0
    return packet
  end
end

#key=(*args) ⇒ Object

Set to a PEM-format client private key



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# File 'lib/mqtt/client.rb', line 209

def key=(*args)
  cert, passphrase = args.flatten
  ssl_context.key = OpenSSL::PKey::RSA.new(cert, passphrase)
end

#key_file=(*args) ⇒ Object

Set a path to a file containing a PEM-format client private key



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# File 'lib/mqtt/client.rb', line 203

def key_file=(*args)
  path, passphrase = args.flatten
  ssl_context.key = OpenSSL::PKey::RSA.new(File.open(path), passphrase)
end

#publish(topic, payload = '', retain = false, qos = 0) ⇒ Object

Publish a message on a particular topic to the MQTT server.

Raises:

  • (ArgumentError)


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# File 'lib/mqtt/client.rb', line 341

def publish(topic, payload='', retain=false, qos=0)
  raise ArgumentError.new("Topic name cannot be nil") if topic.nil?
  raise ArgumentError.new("Topic name cannot be empty") if topic.empty?

  packet = MQTT::Packet::Publish.new(
    :id => next_packet_id,
    :qos => qos,
    :retain => retain,
    :topic => topic,
    :payload => payload
  )

  # Send the packet
  res = send_packet(packet)

  if packet.qos > 0
    Timeout.timeout(@ack_timeout) do
      while connected? do
        @pubacks_semaphore.synchronize do
          return res if @pubacks.delete(packet.id)
        end
        # FIXME: make threads communicate with each other, instead of polling
        # (using a pipe and select ?)
        sleep 0.01
      end
    end
    return -1
  end
end

#queue_empty?Boolean

Returns true if the incoming message queue is empty.

Returns:

  • (Boolean)


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# File 'lib/mqtt/client.rb', line 449

def queue_empty?
  @read_queue.empty?
end

#queue_lengthObject

Returns the length of the incoming message queue.



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# File 'lib/mqtt/client.rb', line 454

def queue_length
  @read_queue.length
end

#remote_hostObject

Deprecated.

Please use #host instead



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# File 'lib/mqtt/client.rb', line 588

def remote_host
  host
end

#remote_host=(args) ⇒ Object

Deprecated.

Please use #host= instead



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# File 'lib/mqtt/client.rb', line 593

def remote_host=(args)
  self.host = args
end

#remote_portObject

Deprecated.

Please use #port instead



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# File 'lib/mqtt/client.rb', line 598

def remote_port
  port
end

#remote_port=(args) ⇒ Object

Deprecated.

Please use #port= instead



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# File 'lib/mqtt/client.rb', line 603

def remote_port=(args)
  self.port = args
end

#set_will(topic, payload, retain = false, qos = 0) ⇒ Object

Set the Will for the client

The will is a message that will be delivered by the server when the client dies. The Will must be set before establishing a connection to the server



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# File 'lib/mqtt/client.rb', line 226

def set_will(topic, payload, retain=false, qos=0)
  self.will_topic = topic
  self.will_payload = payload
  self.will_retain = retain
  self.will_qos = qos
end

#ssl_contextObject

Get the OpenSSL context, that is used if SSL/TLS is enabled



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# File 'lib/mqtt/client.rb', line 188

def ssl_context
  @ssl_context ||= OpenSSL::SSL::SSLContext.new
end

#subscribe(*topics) ⇒ Object

Send a subscribe message for one or more topics on the MQTT server. The topics parameter should be one of the following:

  • String: subscribe to one topic with QoS 0

  • Array: subscribe to multiple topics with QoS 0

  • Hash: subscribe to multiple topics where the key is the topic and the value is the QoS level

For example:

client.subscribe( 'a/b' )
client.subscribe( 'a/b', 'c/d' )
client.subscribe( ['a/b',0], ['c/d',1] )
client.subscribe( 'a/b' => 0, 'c/d' => 1 )


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# File 'lib/mqtt/client.rb', line 383

def subscribe(*topics)
  packet = MQTT::Packet::Subscribe.new(
    :id => next_packet_id,
    :topics => topics
  )
  send_packet(packet)
end

#unsubscribe(*topics) ⇒ Object

Send a unsubscribe message for one or more topics on the MQTT server



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# File 'lib/mqtt/client.rb', line 459

def unsubscribe(*topics)
  if topics.is_a?(Enumerable) and topics.count == 1
    topics = topics.first
  end

  packet = MQTT::Packet::Unsubscribe.new(
    :topics => topics,
    :id => next_packet_id
  )
  send_packet(packet)
end