--- name: "AnyEvent::RabbitMQ::Channel" section: "3pm" platform: "linux" package: "libanyevent-rabbitmq-perl" version: "1.22~dfsg-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/AnyEvent::RabbitMQ::Channel" --- # AnyEvent::RabbitMQ::Channel(3pm) Abstraction of an AMQP channel. ## NAME AnyEvent::RabbitMQ::Channel - Abstraction of an AMQP channel. ## SYNOPSIS ``` my $ch = $rf->open_channel(); $ch->declare_exchange(exchange => 'test_exchange'); ``` ## DESCRIPTION A RabbitMQ channel. A channel is a light-weight virtual connection within a TCP connection to a RabbitMQ broker. ## ARGUMENTS FOR "open\_channel" - on\_close Callback invoked when the channel closes. Callback will be passed the incoming message that caused the close, if any. - on\_return Callback invoked when a mandatory or immediate message publish fails. Callback will be passed the incoming message, with accessors `"method_frame"`, `"header_frame"`, and `"body_frame"`. ## METHODS ### declare\_exchange (%args) Declare an exchange (to publish messages to) on the server. Arguments: - on\_success - on\_failure - type Default 'direct' - passive Default 0 - durable Default 0 - auto\_delete Default 0 - internal Default 0 - exchange The name of the exchange ### bind\_exchange Binds an exchange to another exchange, with a routing key. Arguments: - source The name of the source exchange to bind - destination The name of the destination exchange to bind - routing\_key The routing key to bind with ### unbind\_exchange ### delete\_exchange ### declare\_queue Declare a queue (create it if it doesn't exist yet) for publishing messages to on the server. ``` my $done = AnyEvent->condvar; $channel->declare_queue( exchange => $queue_exchange, queue => $queueName, durable => 0, auto_delete => 1, passive => 0, arguments => { 'x-expires' => 0, }, on_success => sub { $done->send; }, on_failure => sub { say "Unable to create queue $queueName"; $done->send; }, ); $done->recv; ``` Arguments: - queue Name of the queue to be declared. If the queue name is the empty string, RabbitMQ will create a unique name for the queue. This is useful for temporary/private reply queues. - on\_success Callback that is called when the queue was declared successfully. The argument to the callback is of type Net::AMQP::Frame::Method. To get the name of the Queue (if you declared it with an empty name), you can say ``` on_success => sub { my $method = shift; my $name = $method->method_frame->queue; }; ``` - on\_failure Callback that is called when the declaration of the queue has failed. - auto\_delete 0 or 1, default 0 - passive 0 or 1, default 0 - durable 0 or 1, default 0 - exclusive 0 or 1, default 0 - no\_ack 0 or 1, default 1 - ticket default 0 - arguments `"arguments"` is a hashref of additional parameters which RabbitMQ extensions may use. This list is not complete and your RabbitMQ server configuration will determine which arguments are valid and how they act. - x-expires The queue will automatically be removed after being idle for this many milliseconds. Default of 0 disables automatic queue removal. ### bind\_queue Binds a queue to an exchange, with a routing key. Arguments: - queue The name of the queue to bind - exchange The name of the exchange to bind - routing\_key The routing key to bind with ### unbind\_queue ### purge\_queue Flushes the contents of a queue. ### delete\_queue Deletes a queue. The queue may not have any active consumers. ### consume Subscribe to consume messages from a queue. Arguments: - queue The name of the queue to be consumed from. - on\_consume Callback called with an argument of the message which has been consumed. The message is a hash reference, where the value to key `"header"` is an object of type Net::AMQP::Protocol::Basic::ContentHeader, body is a Net::AMQP::Frame::Body, and `"deliver"` a Net::AMQP::Frame::Method. - on\_cancel Callback called if consumption is cancelled. This may be at client request or as a side effect of queue deletion. (Notification of queue deletion is a RabbitMQ extension.) - consumer\_tag Identifies this consumer, will be auto-generated if you do not provide it, but you must supply a value if you want to be able to later cancel the subscription. - on\_success Callback called if the subscription was successful (before the first message is consumed). - on\_failure Callback called if the subscription fails for any reason. - no\_ack Pass through the `"no_ack"` flag. Defaults to `1`. If set to `1`, the server will not expect messages to be acknowledged. ### publish Publish a message to an exchange. Arguments: - exchange The name of the exchange to send the message to. - routing\_key The routing key with which to publish the message. - header Hash of AMQP message header info, including the confusingly similar element "headers", which may contain arbitrary string key/value pairs. - body The text body of the message to send. - mandatory Boolean; if true, then if the message doesn't land in a queue (e.g. the exchange has no bindings), it will be "returned." (see "on\_return") - immediate Boolean; if true, then if the message cannot be delivered directly to a consumer, it will be "returned." (see "on\_return") - on\_ack Callback called with the frame that acknowledges receipt (if channel is in confirm mode), typically Net::AMQP::Protocol::Basic::Ack. - on\_nack Callback called with the frame that declines receipt (if the channel is in confirm mode), typically Net::AMQP::Protocol::Basic::Nack or Net::AMQP::Protocol::Channel::Close. - on\_return In AMQP, a "returned" message is one that cannot be delivered in compliance with the `"immediate"` or `"mandatory"` flags. If in confirm mode, this callback will be called with the frame that reports message return, typically Net::AMQP::Protocol::Basic::Return. If confirm mode is off or this callback is not provided, then the channel or connection objects' on\_return callbacks (if any), will be called instead. NOTE: If confirm mode is on, the on\_ack or on\_nack callback will be called whether or not on\_return is called first. ### cancel Cancel a queue subscription. Note that the cancellation **will not** take place at once, and further messages may be consumed before the subscription is cancelled. No further messages will be consumed after the on\_success callback has been called. Arguments: - consumer\_tag Identifies this consumer, needs to be the value supplied when the queue is initially consumed from. - on\_success Callback called if the subscription was successfully cancelled. - on\_failure Callback called if the subscription could not be cancelled for any reason. ### get Try to get a single message from a queue. Arguments: - queue Mandatory. Name of the queue to try to receive a message from. - on\_success Will be called either with either a message, or, if the queue is empty, a notification that there was nothing to collect from the queue. - on\_failure This callback will be called if an error is signalled on this channel. - no\_ack 0 or 1, default 1 ### ack ### qos ### confirm Put channel into confirm mode. In confirm mode, publishes are confirmed by the server, so the on\_ack callback of publish works. ### recover ### select\_tx ### commit\_tx ### rollback\_tx ## AUTHOR, COPYRIGHT AND LICENSE See AnyEvent::RabbitMQ for author(s), copyright and license.