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 112
def self.channel
  @channel
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 122
def self.channel=(value)
  @channel = value
end

@private

# File lib/amqp/client.rb, line 94
def self.client
  @client_implementation ||= AMQP::Session
end

@private

# File lib/amqp/client.rb, line 99
def self.client=(value)
  @client_implementation = value
end

Indicates that default connection is closing.

@return [Boolean] @api public

# File lib/amqp/connection.rb, line 82
def self.closing?
  @connection.closing?
end

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

# File lib/amqp/connection.rb, line 135
def self.conn
  warn "AMQP.conn will be removed in 1.0. Please use AMQP.connection."
  @connection
end

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

# File lib/amqp/connection.rb, line 143
def self.conn=(value)
  warn "AMQP.conn= will be removed in 1.0. Please use AMQP.connection=(connection)."
  self.connection = value
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 [call] :on_tcp_connection_failure A callable object that will be run if connection to server fails @option connection_options_or_string [call] :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 call) 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 212
def self.connect(connection_options_or_string = {}, other_options = {}, &block)
  Client.connect(connection_options_or_string, other_options, &block)
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 102
def self.connection
  @connection
end

Sets global connection object. @api public

# File lib/amqp/connection.rb, line 128
def self.connection=(value)
  @connection = value
end

@deprecated @private

# File lib/amqp/deprecated/fork.rb, line 7
def self.fork(workers)
  EM.fork(workers) do
    # clean up globals in the fork
    Thread.current[:mq] = nil
    AMQP.instance_variable_set('@conn', nil)

    yield
  end
end

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

# File lib/amqp/connection.rb, line 88
def self.logging
  self.settings[:logging]
end

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

# File lib/amqp/connection.rb, line 94
def self.logging=(value)
  self.settings[:logging] = !!value
end

Alias for {AMQP.start} @api public

# File lib/amqp/connection.rb, line 48
def self.run(*args, &block)
  self.start(*args, &block)
end

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

# File lib/amqp/connection.rb, line 218
def self.settings
  @settings ||= AMQ::Client::Settings.default
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 36
def self.start(connection_options_or_string = {}, other_options = {}, &block)
  EM.run do
    if !@connection || @connection.closed? || @connection.closing?
      @connection   = connect(connection_options_or_string, other_options, &block)
    end
    @channel      = Channel.new(@connection)
    @connection
  end
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 59
def self.stop(reply_code = 200, reply_text = "Goodbye", &block)
  return if @connection.nil? || self.closing?

  EM.next_tick do
    if AMQP.channel and AMQP.channel.open? and AMQP.channel.connection.open?
      AMQP.channel.close
    end
    AMQP.channel = nil


    shim = Proc.new {
      block.call

      AMQP.connection = nil
    }
    @connection.disconnect(reply_code, reply_text, &shim)
  end
end