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https://github.com/cloudamqp/amqp-client.cr

An AMQP 0-9-1 client for Crystal
https://github.com/cloudamqp/amqp-client.cr

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An AMQP 0-9-1 client for Crystal

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# amqp-client



An AMQP 0-9-1 client for Crystal.



## Installation



1. Add the dependency to your `shard.yml`:

```yaml

dependencies:

  amqp-client:

    github: cloudamqp/amqp-client.cr

```

2. Run `shards install`



## Usage



```crystal

require "amqp-client"



AMQP::Client.start("amqp://guest:guest@localhost") do |c|

  c.channel do |ch|

    # Always set a prefetch limit before consuming

    ch.prefetch(100)



    # Declare a temporary queue

    q = ch.queue("")



    # Declare a durable queue

    q = ch.queue("my-queue")



    # Subscribe to it, and manually acknowledge messages when processed

    q.subscribe(no_ack: false) do |msg|

      puts "Received: #{msg.body_io.to_s}"

      ch.basic_ack(msg.delivery_tag)

    end



    # publish directly to a queue without confirm (fire and forget)

    q.publish "msg"



    # publish directly to a queue and blocking while waiting for confirm

    q.publish_confirm "msg"



    # publish to any exchange/routing-key (fire and forget)

    ch.basic_publish "msg", exchange: "amq.topic", routing_key: "a"



    # publish to any exchange/routing-key and block while waiting for confirm

    ch.basic_publish_confirm "msg", exchange: "amq.topic", routing_key: "a"



    # When the Channel is in confirm mode a block can be given to the basic_publish

    # method and it will be executed when the message is confirmed by the server

    ch.confirm_select

    ch.basic_publish("msg", "amq.topic", "my.topic") do |ok|

      if ok

        puts "Message is confirmed by the server"

      else

        puts "Message was NOT confirmed by the server"

      end

    end



    # This statement will block until a message has arrived

    # The only way to "escape" the block is to unsubscribe

    q.subscribe(tag: "myconsumer", block: true) do |msg|

      q.unsubscribe("myconsumer")

    end



    # Consume and ack, nack or reject msgs

    ch.basic_consume("queue", tag: "consumer-tag", no_ack: false, exclusive: false, block: false) do |msg|

      case msg.body_io.to_s

      when "ack"

        ch.basic_ack(msg.delivery_tag)

      when "reject"

        ch.basic_reject(msg.delivery_tag, requeue: true)

      when "nack"

        ch.basic_nack(msg.delivery_tag, requeue: true, multiple: true)

      end

    end



    ch.prefetch(count: 1000) # alias for basic_qos



    name, message_count, consumer_count =

      ch.queue_declare(name: "myqueue", passive: false, durable: true,

                       exclusive: false, auto_delete: false,

                       arguments: AMQP::Client::Arguments.new)

    q = ch.queue # temporary queue that is deleted when the channel is closed

    ch.queue_purge("myqueue")

    ch.queue_bind("myqueue", "amq.topic", "routing-key")

    ch.queue_unbind("myqueue", "amq.topic", "routing-key")

    msg = ch.basic_get("myqueue", no_ack: true)

    ch.basic_ack(msg.delivery_tag)

    ch.queue_delete("myqueue")

    ch.exchange_declare("my-exchange", type: "topic")

    ch.exchange_delete("my-exchange")

  end

end

```



You can consume [stream queues](https://www.rabbitmq.com/streams.html) too: 



```crystal

require "amqp-client"



AMQP::Client.start do |c|

  c.channel do |ch|

    # prefetch required when consuming from stream queues

    ch.prefetch(10)

    # declare a stream queue using the x-queue-type argument

    q = ch.queue("stream1", args: AMQP::Client::Arguments.new({"x-queue-type": "stream"}))

    puts "Waiting for messages. To exit press CTRL+C"

    # Decide from where to subscribe using the x-stream-offset argument

    q.subscribe(block: true, no_ack: false, args: AMQP::Client::Arguments.new({"x-stream-offset": "first"})) do |msg|

      puts "Received: #{msg.body_io}"

      msg.ack

    end

  end

end

```



## Performance



1-byte messages, without properties/headers:



| Publish rate | Consume rate |

| ------------ | ------------ |

| 1.200.000 msgs/s | 1.000.000 msgs/s |



## Contributing



1. [Fork it](https://github.com/cloudamqp/amqp-client.cr/fork)

2. Create your feature branch (`git checkout -b my-new-feature`)

3. Commit your changes (`git commit -am 'Add some feature'`)

4. Push to the branch (`git push origin my-new-feature`)

5. Create a new Pull Request



## Contributors



- [Carl Hörberg](https://github.com/carlhoerberg) - creator and maintainer

- [Anders Bälter](https://github.com/baelter)