class BanyanBase

This class is used as a base class to create a Banyan compatible component that connects to a single Banyan Backplane. A banyan component inherits and extends this class to encapsulate zeromq and message pack functionality. Its methods may be overridden by the user in the derived class to meet the needs of the component. noinspection ALL

Public Class Methods

new(back_plane_ip_address: nil, subscriber_port: '43125', publisher_port: '43124', process_name: 'Unnamed', loop_time: 0.1) click to toggle source

Parameters:
 back_plane_ip_address: banyan_base back_planeIP Address.
                        If not specified, it will be set to the
                        IP address of local computer.
 subscriber_port:       banyan_base back plane subscriber port.
                        This must match that of the banyan_base backplane
 publisher_port:        banyan_base back plane publisher port.
                        This must match that of the banyan_base backplane
 process_name:          Component identifier
 loop_time:             receive loop sleep time.

Example Usage:

require 'rubygems'
require 'rb_banyan/banyan_base.rb'
class Myexample < BanyanBase

 def initialize
   super(process_name: 'MyExample')
 end
end

MyExample.new

=> This banner appears in the console

***********************************************************************
*****  Reminder: Make Sure That The Backplane is Already Running  *****
***********************************************************************

************************************************************
MyExample using BackPlane IP address: 192.168.2.194
Subscriber Port = 43125
Publisher  Port = 43124
Loop Time = 0.1 seconds
************************************************************

# File lib/rb_banyan/banyan_base.rb, line 76
def initialize(back_plane_ip_address: nil, subscriber_port: '43125',
               publisher_port: '43124', process_name: 'Unnamed',
               loop_time: 0.1)
  # If no back plane address was specified, determine the IP address
  # of the local machine
  if back_plane_ip_address.nil?
    @back_plane_ip_address = Socket.ip_address_list[1].ip_address
  else
    @back_plane_ip_address = back_plane_ip_address
  end
  @subscriber_port = subscriber_port
  @publisher_port = publisher_port
  @process_name = process_name
  @loop_time = loop_time

  puts('***********************************************************************')
  puts('*****  Reminder: Make Sure That The Backplane is Already Running  *****')
  puts('***********************************************************************')
  puts

  puts('************************************************************')
  # noinspection RubyResolve
  puts(@process_name + ' using BackPlane IP address: ' +
           @back_plane_ip_address)
  puts('Subscriber Port = ' + @subscriber_port)
  puts('Publisher  Port = ' + @publisher_port)
  puts('Loop Time = ' + (@loop_time.to_s) + ' seconds')
  puts('************************************************************')

  # establish the zeromq sub and pub sockets and connect to the backplane
  @context = ZMQ::Context.create
  @subscriber = @context.socket ZMQ::SUB
  # noinspection RubyResolve
  @subscriber.connect 'tcp://' + @back_plane_ip_address + ':' + @subscriber_port

  @publisher = @context.socket ZMQ::PUB
  @publisher.connect 'tcp://' + @back_plane_ip_address + ':' + @publisher_port

  trap('INT') {'puts Control C detected - bye bye.'; @publisher.close; @subscriber.close; @context.terminate; exit}
end

Public Instance Methods

clean_up() click to toggle source

This method closes all zmq connections.

# File lib/rb_banyan/banyan_base.rb, line 183
def clean_up
  @publisher.close
  @subscriber.close
  @context.terminate
end

incoming_message_processing(topic, payload) click to toggle source

This method should be overwritten to process incoming messages.

Parameters:
  topic: Message topic - must be in the form of a string
  payload: Message payload in the form of a hash

# File lib/rb_banyan/banyan_base.rb, line 178
def incoming_message_processing(topic, payload)
  puts(topic, payload)
end

publish_payload(payload, topic) click to toggle source

This method will publish a python_banyan payload and its associated topic

Parameters:
  payload: Message payload in the form of a hash
  topic: Message topic - must be in the form of a string

# File lib/rb_banyan/banyan_base.rb, line 136
def publish_payload(payload, topic)
  if topic.is_a? String
    message = payload.to_msgpack
    pub_envelope = topic.encode('UTF-8')
    @publisher.send_strings([pub_envelope, message], flags = ZMQ::DONTWAIT)
  else
    raise TypeError, 'Subscriber topic must be a string'
  end

end

receive_loop() click to toggle source

receive_loop

This is the receive loop for zmq messages.

This method may be overwritten to meet the needs of the application before handling received messages.

# File lib/rb_banyan/banyan_base.rb, line 153
def receive_loop
  loop do
    list = []
    p = @subscriber.recv_strings(list, ZMQ::DONTWAIT)
    begin
      if p == -1
        if ZMQ::Util.errno == ZMQ::EAGAIN
          sleep(@loop_time)
        else
          sleep(@loop_time)
          puts ZMQ::Util.errno
        end
      else
        incoming_message_processing(list[0], MessagePack.unpack(list[1]))
      end
    rescue Interrupt
      clean_up
    end
  end
end

set_subscriber_topic(topic) click to toggle source

This method sets a subscriber topic.

Parameters:
  topic: Message topic - must be in the form of a string

# File lib/rb_banyan/banyan_base.rb, line 120
def set_subscriber_topic(topic)

  # You can subscribe to multiple topics by calling this method for
  # each topic.

  if topic.is_a? String
    @subscriber.setsockopt ZMQ::SUBSCRIBE, topic
  else
    raise TypeError, 'Subscriber topic must be a string'
  end
end