Duct RabbitMQ
Integrant methods for connecting to a RabbitMQ server via Langohr.
Installation
To install, add the following to your project :dependencies
[viebel/rabbitmq "0.1.2"]
Usage
This library provides:
- a multimethod for
:duct.amqp.rabbitmq/langohrthat initiates the connection based on the settings. - a multimethod for
:duct.amqp.rabbitmq/langohr-consumersthat subscribes handlers on queues. - a multimethod for
:duct.amqp.rabbitmq/langohr-producersthat creates publish functions for producers.
Connection
URI
:duct.amqp.rabbitmq/langohr {:host "localhost"
:port 5672
:username "guest"
:password "guest"
:vhost "/"}Consumers
:duct.amqp.rabbitmq/langohr-consumers {:consumers [{:queue "my-queue"
:declare-queue {:durable false
:exclusive false
:auto-delete true
:arguments {}}
:handler #ig/ref :my-prj.handler/handle-msg}]
:connection #ig/ref :duct.amqp.rabbitmq/langohr}
:my-prj.handler/handle-msg {}Note: You can optionally pass a duct logger. If you do so, a message will be logged for each queue subscriber, when it subscribes.
:duct.amqp.rabbitmq/langohr-consumers {:consumers [{:queue "my-queue"
:declare-queue {:durable false
:exclusive false
:auto-delete true
:arguments {}}
:handler #ig/ref :my-prj.handler/handle-msg}]
:connection #ig/ref :duct.amqp.rabbitmq/langohr
:logger #ig/reg :duct/logger}
:my-prj.handler/handle-msg {}(defmethod ig/init-key :my-prj.handler/handle-msg [_ _]
(fn [ch {:keys [content-type delivery-tag type] :as meta} ^bytes payload]
(println (format "[consumer] Received a message: %s, delivery tag: %d, content type: %s, type: %s" (String. payload "UTF-8") delivery-tag content-type type))))Instead of :connection, you can have :connection-settings like this:
:duct.amqp.rabbitmq/langohr-consumers {:consumers [{:queue "my-queue"
:declare-queue {:durable false
:exclusive false
:auto-delete true
:arguments {}}
:handler #ig/ref :my-prj.handler/handle-msg}]
:connection-settings {:host "localhost"
:port 5672
:username "guest"
:password "guest"
:vhost "/"}
:my-prj.handler/handle-msg {}Producers
:duct.amqp.rabbitmq/langohr-producers {:producers [{:name "my-producer"
:exchange "my-excahnge"
:routing-key "my-key"}]
:connection #ig/ref :duct.amqp.rabbitmq/langohr}The return value is a map whose keys are the name of the producers (left as strings) and hte values and the values are a map {:publish-fn fun :ch ch}, where fun is a function that publishes to the corresponding exchange and routing key according to langohr.basic/publish semantics, where the two first parameters are fixed according to the specified exchange and routing key in the settings.
(def publish (get-in system [:duct.amqp.rabbitmq/langohr-producers "my-producer" :publish-fn]))
(publish "Hello!" {:content-type "text/plain" :type "greetings.hi"})Instead of :connection, you can have :connection-settings like we showed in the Consumers section.
Example
Consider an application that passes messages to itslef through RabbitMQ.
The duct config might look like this:
{:duct.amqp.rabbitmq/langohr {:host "localhost"
:port 5672
:username "guest"
:password "guest"
:vhost "/"}
:duct.amqp.rabbitmq/langohr-consumers {:consumers [{:queue "my-queue"
:declare-queue {:durable false
:exclusive false
:auto-delete true
:arguments {}}
:handler #ig/ref :my-prj.handler/handle-msg}]
:connection #ig/ref :duct.amqp.rabbitmq/langohr}
:my-prj.handler/handle-msg {}
:duct.amqp.rabbitmq/langohr-producers {:producers [{:name "my-producer"
:exchange "my-excahnge"
:routing-key "my-key"}]
:connection #ig/ref :duct.amqp.rabbitmq/langohr}
}And the producers and consumers might be initialized like this:
(defmethod ig/init-key :my-prj.handler/handle-msg [_ _]
(fn [ch {:keys [content-type delivery-tag type] :as meta} ^bytes payload]
(println (format "[consumer] Received a message: %s, delivery tag: %d, content type: %s, type: %s" (String. payload "UTF-8") delivery-tag content-type type))))
(def publish (get-in system [:duct.amqp.rabbitmq/langohr-producers "my-producer" :publish-fn]))
(publish "Hello!" {:content-type "text/plain" :type "greetings.hi"})
For more information using Langohr, you can start with their getting started webpage.
License
Copyright © 2019 Yehonathan Sharvit
Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.
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