AMQP

“Default channel”. A placeholder for apps that only want to use one channel. This channel is not global, not used under the hood by methods like {AMQP::Exchange#initialize} and only shared by exchanges/queues you decide on. To reiterate: this is only a conventience accessor, since many apps (especially Web apps) can get by with just one connection and one channel.

@api public

     # File lib/amqp/connection.rb, line 113
113:   def self.channel
114:     @channel
115:   end

A placeholder for applications that only need one channel. If you use {AMQP.start} to set up default connection, {AMQP.channel} is open on that connection, but can be replaced by your application.

@see AMQP.channel @api public

     # File lib/amqp/connection.rb, line 123
123:   def self.channel=(value)
124:     @channel = value
125:   end

@private

    # File lib/amqp/client.rb, line 95
95:   def self.client
96:     @client_implementation ||= AMQP::Session
97:   end

@private

     # File lib/amqp/client.rb, line 100
100:   def self.client=(value)
101:     @client_implementation = value
102:   end

Indicates that default connection is closing.

@return [Boolean] @api public

    # File lib/amqp/connection.rb, line 83
83:   def self.closing?
84:     @connection.closing?
85:   end

Alias for {AMQP.connection} @deprecated @api public

     # File lib/amqp/connection.rb, line 136
136:   def self.conn
137:     warn "AMQP.conn will be removed in 1.0. Please use AMQP.connection."
138:     @connection
139:   end

Alias for {AMQP.connection=} @deprecated @api public

     # File lib/amqp/connection.rb, line 144
144:   def self.conn=(value)
145:     warn "AMQP.conn= will be removed in 1.0. Please use AMQP.connection=(connection)."
146:     self.connection = value
147:   end

Connects to AMQP broker and yields connection object to the block as soon as connection is considered open.

@example Using AMQP.connect with default connection settings

  AMQP.connect do |connection|
    AMQP::Channel.new(connection) do |channel|
      # channel is ready: set up your messaging flow by creating exchanges,
      # queues, binding them together and so on.
    end
  end

@example Using AMQP.connect to connect to a public RabbitMQ instance with connection settings given as a hash

  AMQP.connect(:host => "dev.rabbitmq.com", :username => "guest", :password => "guest") do |connection|
    AMQP::Channel.new(connection) do |channel|
      # ...
    end
  end

@example Using AMQP.connect to connect to a public RabbitMQ instance with connection settings given as a URI

  AMQP.connect "amqp://guest:guest@dev.rabbitmq.com:5672", :on_possible_authentication_failure => Proc.new { puts("Looks like authentication has failed") } do |connection|
    AMQP::Channel.new(connection) do |channel|
      # ...
    end
  end

@overload connect(connection_string, options = {})

  Used to pass connection parameters as a connection string
  @param [String] :connection_string AMQP connection URI, à la JDBC connection string. For example: amqp://bus.megacorp.internal:5877/qa

@overload connect(connection_options)

  Used to pass connection options as a Hash.
  @param [Hash] :connection_options AMQP connection options (:host, :port, :username, :vhost, :password)

@option connection_options_or_string [String] :host (“localhost”) Host to connect to. @option connection_options_or_string [Integer] :port (5672) Port to connect to. @option connection_options_or_string [String] :vhost (“/”) Virtual host to connect to. @option connection_options_or_string [String] :username (“guest”) Username to use. Also can be specified as :user. @option connection_options_or_string [String] :password (“guest”) Password to use. Also can be specified as :pass. @option connection_options_or_string [Hash] :ssl TLS (SSL) parameters to use. @option connection_options_or_string [#] :on_tcp_connection_failure A callable object that will be run if connection to server fails @option connection_options_or_string [#] :on_possible_authentication_failure A callable object that will be run if authentication fails (see Authentication failure section)

h2. Handling authentication failures

AMQP 0.9.1 specification dictates that broker closes TCP connection when it detects that authentication has failed. However, broker does exactly the same thing when other connection-level exception occurs so there is no way to guarantee that connection was closed because of authentication failure.

Because of that, AMQP gem follows Java client example and hints at possibility of authentication failure. To handle it, pass a callable object (a proc, a lambda, an instance of a class that responds to #) with :on_possible_authentication_failure option.

@note This method assumes that EventMachine even loop is already running. If it is not the case or you are not sure, we recommend you use {AMQP.start} instead.

      It takes exactly the same parameters.

@return [AMQP::Session] @api public

     # File lib/amqp/connection.rb, line 213
213:   def self.connect(connection_options_or_string = {}, other_options = {}, &block)
214:     Client.connect(connection_options_or_string, other_options, &block)
215:   end

Default connection. When you do not pass connection instance to methods like {Channel#initialize}, AMQP gem will use this default connection.

@api public

     # File lib/amqp/connection.rb, line 103
103:   def self.connection
104:     @connection
105:   end

Sets global connection object. @api public

     # File lib/amqp/connection.rb, line 129
129:   def self.connection=(value)
130:     @connection = value
131:   end

@deprecated @private

    # File lib/amqp/deprecated/fork.rb, line 8
 8:   def self.fork(workers)
 9:     EM.fork(workers) do
10:       # clean up globals in the fork
11:       Thread.current[:mq] = nil
12:       AMQP.instance_variable_set('@conn', nil)
13: 
14:       yield
15:     end
16:   end

@return [Boolean] Current global logging value @api public

    # File lib/amqp/connection.rb, line 89
89:   def self.logging
90:     self.settings[:logging]
91:   end

@return [Boolean] Sets current global logging value @api public

    # File lib/amqp/connection.rb, line 95
95:   def self.logging=(value)
96:     self.settings[:logging] = !!value
97:   end

Alias for {AMQP.start} @api public

    # File lib/amqp/connection.rb, line 49
49:   def self.run(*args, &block)
50:     self.start(*args, &block)
51:   end

@return [Hash] Default AMQP connection settings. This hash may be modified. @api public

     # File lib/amqp/connection.rb, line 219
219:   def self.settings
220:     @settings ||= AMQ::Client::Settings.default
221:   end

Starts EventMachine event loop unless it is already running and connects to AMQP broker using {AMQP.connect}. It is generally a good idea to start EventMachine event loop in a separate thread and use {AMQP.connect} (for Web applications that do not use Thin or Goliath, it is the only option).

See {AMQP.connect} for information about arguments this method takes and information about relevant topics such as authentication failure handling.

@example Using AMQP.start to connect to AMQP broker, EventMachine loop isn’t yet running

 AMQP.start do |connection|
   # default is to connect to localhost:5672, to root ("/") vhost as guest/guest

   # this block never exits unless either AMQP.stop or EM.stop
   # is called.

   AMQP::Channel(connection) do |channel|
     channel.queue("", :auto_delete => true).bind(channel.fanout("amq.fanout")).subscribe do |headers, payload|
       # handle deliveries here
     end
   end
 end

@api public

    # File lib/amqp/connection.rb, line 37
37:   def self.start(connection_options_or_string = {}, other_options = {}, &block)
38:     EM.run do
39:       if !@connection || @connection.closed? || @connection.closing?
40:         @connection   = connect(connection_options_or_string, other_options, &block)
41:       end
42:       @channel      = Channel.new(@connection)
43:       @connection
44:     end
45:   end

Properly closes default AMQP connection and then underlying TCP connection. Pass it a block if you want a piece of code to be run once default connection is successfully closed.

@note If default connection was never estabilished or is in the closing state already,

      this method has no effect.

@api public

    # File lib/amqp/connection.rb, line 60
60:   def self.stop(reply_code = 200, reply_text = "Goodbye", &block)
61:     return if @connection.nil? || self.closing?
62: 
63:     EM.next_tick do
64:       if AMQP.channel and AMQP.channel.open? and AMQP.channel.connection.open?
65:         AMQP.channel.close
66:       end
67:       AMQP.channel = nil
68: 
69: 
70:       shim = Proc.new {
71:         block.call
72: 
73:         AMQP.connection = nil
74:       }
75:       @connection.disconnect(reply_code, reply_text, &shim)
76:     end
77:   end