The following is the logstash-zeromq server for zeromq filter

logstash.rb

#!/usr/bin/env ruby

## Please compile and install zeromq before running this script.

require 'rubygems'
require 'ffi-rzmq'
require 'json'
context = ZMQ::Context.new(1)


# socket to listen for clients
socket = context.socket(ZMQ::REP)
socket.bind("tcp://*:8080")

while true do
  # Wait for next request from client
  request = ''
  rc = socket.recv_string(request)
  
  puts "Received request. Data: #{request.inspect}"


  data = JSON.parse(request) 
  # Do some 'processing'

  # Send reply back to client
  
  if data['message'].match(/logstash/)
    data['zeromq'] = true
  end
  socket.send_string(data.to_json)
end