/ 
Net-Async-AMQP-1.000
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/ Net::Async::AMQP::Channel

NAME

Net::Async::AMQP::Channel - represents a single channel in an MQ connection

VERSION

version 1.000

SYNOPSIS

use IO::Async::Loop;
use Net::Async::AMQP;
my $loop = IO::Async::Loop->new;
$loop->add(my $amqp = Net::Async::AMQP->new);
$amqp->connect(
  host => 'localhost',
  username => 'guest',
  password => 'guest',
)->then(sub {
 shift->open_channel->publish(
  type => 'application/json'
 )
});

DESCRIPTION

Each Net::Async::AMQP::Channel instance represents a virtual channel for communicating with the MQ server.

Channels are layered over the TCP protocol and most of the common AMQP frames operate at channel level - typically you'd connect to the server, open one channel for one-shot requests such as binding/declaring/publishing, and a further channel for every consumer.

Since any error typically results in a closed channel, it's not recommended to have multiple consumers on the same channel if there's any chance the Basic.Consume request will fail.

METHODS

confirm_mode

Switches confirmation mode on for this channel. In confirm mode, all messages must be ACKed explicitly after delivery.

Note that this is an irreversible operation - once confirm mode has been enabled on a channel, closing that channel and reopening is the only way to turn off confirm mode again.

Returns a Future which will resolve with this channel once complete.

$ch->confirm_mode ==> $ch

nowait_from_args

If we have a wait argument, then return the inverse of that.

Otherwise, return zero.

exchange_declare

Declares a new exchange.

Returns a Future which will resolve with this channel once complete.

$ch->exchange_declare(
 exchange   => 'some_exchange',
 type       => 'fanout',
 autodelete => 1,
) ==> $ch

exchange_bind

Binds an exchange to another exchange. This is a RabbitMQ-specific extension.

queue_declare

Returns a Future which will resolve with the new Net::Async::AMQP::Queue instance, the number of messages in the queue, and the number of consumers.

$ch->queue_declare(
 queue      => 'some_queue',
) ==> ($q, $message_count, $consumer_count)

publish

Publishes a message on this channel.

Returns a Future which will resolve with the channel instance once the server has confirmed publishing is complete.

$ch->publish(
 exchange => 'some_exchange',
 routing_key => 'some.rkey.here',
 type => 'some_type',
) ==> $ch

Some named parameters currently accepted - note that this list is likely to expand in future:

  • ack - we default to ACK mode, so set this to 0 to turn off explicit server ACK on message routing/delivery

  • immediate - if set, will cause a failure if the message could not be routed immediately to a consumer

  • mandatory - if set, will require that the message ends up in a queue (i.e. will fail messages sent to an exchange that do not have an appropriate binding)

  • content_type - defaults to application/binary

  • content_encoding - defaults to undef (none)

  • timestamp - the message timestamp, defaults to epoch time

  • expiration - use this to set per-message expiry, see https://www.rabbitmq.com/ttl.html

  • priority - defaults to undef (none), use this to take advantage of RabbitMQ 3.5+ priority support

qos

Changes QOS settings on the channel. Probably most useful for limiting the number of messages that can be delivered to us before we have to ACK/NAK to proceed.

Returns a Future which will resolve with the channel instance once the operation is complete.

$ch->qos(
 prefetch_count => 5,
 prefetch_size  => 1048576,
) ==> $ch

ack

Acknowledge a specific delivery.

Returns a Future which will resolve with the channel instance once the operation is complete.

$ch->ack(
 delivery_tag => 123,
) ==> $ch

Example output:

'method_id' => 40,
'reply_code' => 404,
'class_id' => 60,
'reply_text' => 'NOT_FOUND - no exchange \'invalidchan\' in vhost \'vhost\''

on_close

Called when the channel has been closed.

send_frame

Proxy frame sending requests to the parent Net::Async::AMQP instance.

close

Ask the server to close this channel.

Returns a Future which will resolve with the channel instance once the operation is complete.

$ch->close(
 code => 404,
 text => 'something went wrong',
) ==> $ch

push_pending

remove_pending

Removes a coderef from the pending event handler.

Returns $self .

next_pending

Retrieves the next pending handler for the given incoming frame type (see "amqp_frame_type" in Net::Async::AMQP::Utils), and calls it.

Takes the following parameters:

  • $frame - the frame itself

Returns $self.

METHODS - Accessors

amqp

The parent Net::Async::AMQP instance.

bus

Event bus. Used for sharing channel-specific events.

future

The underlying Future for this channel.

Will resolve to the Net::Async::Channel instance once the channel is open.

id

This channel ID.

closed

Returns true if the channel has been closed, 1 if not (which could mean it is either not yet open, or that it is open and has not yet been closed by either side).

closure_protection

Helper method for marking any outstanding requests as failed when the channel closes.

Takes a Future, returns a Future (probably the same one).

INHERITED METHODS

IO::Async::Notifier

add_child, adopt_future, can_event, children, configure_unknown, debug_printf, get_loop, invoke_error, invoke_event, loop, make_event_cb, maybe_invoke_event, maybe_make_event_cb, new, notifier_name, parent, remove_child, remove_from_parent

AUTHOR

Tom Molesworth <cpan@perlsite.co.uk>

LICENSE

Licensed under the same terms as Perl itself, with additional licensing terms for the MQ spec to be found in share/amqp0-9-1.extended.xml ('a worldwide, perpetual, royalty-free, nontransferable, nonexclusive license to (i) copy, display, distribute and implement the Advanced Messaging Queue Protocol ("AMQP") Specification').