Class: Bayeux

Inherits:
Sinatra::Base
  • Object
show all
Defined in:
lib/bayeux.rb

Overview

A Sinatra application that handles PUTs and POSTs on the /cometd URL, implementing the COMET protocol.

Defined Under Namespace

Classes: Client

Constant Summary collapse

VERSION =

The Gem version of this implementation

"0.6.2"

Instance Method Summary collapse

Instance Method Details

#channels ⇒ Object

A Hash of channels by channel name. Each channel is an Array of subscribed clients



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# File 'lib/bayeux.rb', line 77

def channels
  # Sinatra dup's this object, so we have to use class variables
  @@channels ||= Hash.new {|h, k| h[k] = [] }
end

#clients ⇒ Object

A Hash of all clients by clientId



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# File 'lib/bayeux.rb', line 83

def clients
  @@clients ||= {}
end

#deliver(message) ⇒ Object

Handle a request from a client. Normally over-ridden in the subclass to add server behaviour.



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# File 'lib/bayeux.rb', line 109

def deliver(message)
  id = message['id']
  clientId = message['clientId']
  channel_name = message['channel']

  response =
    case channel_name
    when '/meta/handshake'      # Client says hello, greet them
      clientId = next_client_id
      clients[clientId] = Client.new(clientId)
      trace "Client #{clientId} offers a handshake from #{request.ip}"
      handshake message

    when '/meta/subscribe'      # Client wants to subscribe to a channel:
      subscribe message

    when '/meta/unsubscribe'    # Client wants to unsubscribe from a channel:
      unsubscribe message

    # This is the long-polling request.
    when '/meta/connect'
      connect message

    when '/meta/disconnect'
      disconnect message

    # Other meta channels are disallowed
    when %r{/meta/(.*)}
      trace "Client #{clientId} tried to send a message to #{channel_name}"
      { :successful => false }

    # Service channels default to no-op. Service messages are never broadcast.
    when %r{/service/(.*)}
      trace "Client #{clientId} sent a private message to #{channel_name}"
      { :successful => true }

    else
      puts "Unknown channel in request: "+message.inspect
      pass  # 404
    end

  # Set the standard parameters for all response messages
  if response
    response[:channel] = channel_name
    response[:clientId] = clientId
    response[:id] = id
    [response]
  else
    []
  end
end

#next_client_id ⇒ Object

ClientIds should be strong random numbers containing at least 128 bits of entropy. These aren’t!



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# File 'lib/bayeux.rb', line 88

def next_client_id
  begin
    id = (rand*1_000_000_000).to_i
  end until !clients[id]
  trace "New client recieves ID #{id}"
  id
end

#publish(message) ⇒ Object

Send a message (a Hash) to a channel. The message must have the channel name under the key :channel or “channel”



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# File 'lib/bayeux.rb', line 98

def publish message
  channel = message['channel'] || message[:channel]
  clients = channels[channel]
  trace "publishing to #{channel} with #{clients.size} subscribers: #{message.inspect}"
  clients.each do | client|
    client.queue << message
    client.channel.push true    # Wake up the subscribed client
  end
end

#respond(messages) ⇒ Object

Send an asynchronous JSON or JSONP response to an async_sinatra GET or POST



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# File 'lib/bayeux.rb', line 162

def respond messages
  if jsonp = params['jsonp']
    trace "responding jsonp=#{messages.to_json}"
    headers({'Content-Type' => 'text/javascript'})
    body "#{jsonp}(#{messages.to_json});\n"
  else
    trace "responding #{messages.to_json}"
    headers({'Content-Type' => 'application/json'})
    body messages.to_json
  end
end

#trace(s) ⇒ Object

Trace to stdout if the :tracing setting is enabled



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# File 'lib/bayeux.rb', line 70

def trace s
  if settings.tracing
    puts s
  end
end