Faye ruby client publishing only once - ruby

Question

I have a faye server (nodejs) running on localhost, and I am trying to setup a server side ruby client which needs to publish on the server on a regular basis. This is the code I am trying to use.
(Please ignore the commented code to start with).
I make a class variable ##client and initialize it as soon as the class loads. I define a class method pub whose task is to publish something on the faye server.
In the end, I just call the pub method twice. The first publication callback is received successfully, but the second publication doesn't make either of callback or the errback. And since the control has not been given back to the app, the app just hangs there.
If I make the gobal variable $client (currently commented), the behaviour is the same. But if I make the client everytime pub is called, then the publish goes on smoothly. I initiate it in EM.run loop or outside, the behavior is same. (as expected)
I don't want to make a new connection everytime I want to publish something since that defeats the purpose. Also, if I create a new client in EM.run everytime I call the method, the client connections don't close by themselves. I can see them open in lsof command as open files, and soon I'll start getting too many open files error I think.
I don't really understand Event Machine correctly, maybe I am missing something there.
require 'faye'
require 'eventmachine'
# $client = Faye::Client.new('http://localhost:5050/faye')
class Fayeclient
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
# if !defined? ##client or ##client.nil?
##client = Faye::Client.new('http://localhost:5050/faye')
puts "Created client: " + ##client.inspect
# end
def self.pub
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
# client = Faye::Client.new('http://localhost:5050/faye') #$client
# client = ##client
EM.run {
#client = Faye::Client.new('http://localhost:5050/faye') #$client
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
puts ##client.inspect
publication = ##client.publish('/foo', 'text' =>'Hello world')
puts "Publishing: #{publication.inspect}"
# puts "Publication methods: #{publication.methods}"
publication.callback do
puts "Did it #{publication.inspect}"
EM.stop_event_loop
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
# puts "#{client.methods}"
# puts client.inspect
# client.remove_all_listeners
# puts client.inspect
end
publication.errback do |error |
puts error.inspect
EM.stop_event_loop
end
}
puts "Outside event loop"
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
end
end
Fayeclient.pub
Fayeclient.pub

Answer 1

EM.run call is blocking, you have to run it on a separate thread, and eventually join it when all is over. In the example I'm using Singleton but it's up to you.
This does correctly the 2 faye calls.
#!/usr/bin/env ruby
#
require 'faye'
require 'singleton'
require 'eventmachine'
class Fayeclient
include Singleton
attr_accessor :em_thread, :client
def initialize
self.em_thread = Thread.new do
EM.run
end
self.client = Faye::Client.new('http://localhost:8890/faye')
end
def pub
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
puts client.inspect
publication = client.publish('/foo', 'text' =>'Hello world')
puts "Publishing: #{publication.inspect}"
publication.callback do
puts "Did it #{publication.inspect}"
EM.stop_event_loop
puts "#{__LINE__}: Reactor running: " + EM.reactor_running?.to_s
end
publication.errback do |error |
puts error.inspect
EM.stop_event_loop
end
end
end
Fayeclient.instance.pub
Fayeclient.instance.pub
Fayeclient.instance.em_thread.join
In my personal experience, anyway, having to deal with EventMachine inside Rails application can be a mess, some webserver uses EM, other does not so, and when you want to test from console it may not work as expected.
My solution is to fallback to http calls:
RestClient.post "http://localhost:#{Rails.configuration.faye_port}/faye", message: {foo: 'bar'}.to_json
I found this solution simpler and easy to customize, if you don't need to receive message from this piece of code.