langohr.exchange — com.novemberain/langohr 5.1.0

Functions that provide operations on exchanges.

Relevant guides:

http://clojurerabbitmq.info/articles/exchanges.html

bind clj

(bind channel destination source)

(bind channel
      destination
      source
      {:keys [routing-key arguments] :or {routing-key ""}})

Binds an exchange to another exchange using exchange.bind AMQP method (a RabbitMQ-specific extension)

Options: :routing-key (default: ""): Specifies the routing key for the binding. The routing key is used for routing messages depending on the exchange configuration. Not all exchanges use a routing key - refer to the specific exchange documentation. :arguments (default: nil): A hash of optional arguments with the declaration. Headers exchange type uses these metadata attributes for routing matching. In addition, brokers may implement AMQP extensions using x-prefixed declaration arguments.

declare clj

(declare channel name type)

(declare channel
         name
         type
         {:keys [durable auto-delete internal arguments]
          :or {durable false auto-delete false internal false}})

Declares an exchange using exchange.declare AMQP method.

By default declares non-autodeleted non-durable exchanges.

Core exchange types:

• direct: 1:1 form of communication. Routing key defines how broker will direct message from producer to the consumer.
• fanout: 1:N message delivery pattern. No routing keys are involved. You bind a queue to exchange and messages sent to that exchange are delivered to all bound queues.
• topic: used for 1:n and n:m communication. In this case, routing key is defined as a pattern. For example "langohr.#" will match "langohr.samples" and "langohr.smamples" or "#.samples" will match "langor.samples" and "shmangor.samples".

Usage example:

(lhe/declare channel exchange "direct" :auto-delete false, :durable true)

Options :auto-delete (default: false): If set when creating a new exchange, the exchange will be marked as durable. Durable exchanges remain active when a server restarts. Non-durable exchanges (transient exchanges) are purged if/when a server restarts. :durable (default: false): indicates wether the exchange is durable. Information about Durable Exchanges is persisted and restored after server restart. Non-durable (transient) exchanges do not survive the server restart. :internal (default: false): If set, the exchange may not be used directly by publishers, but only when bound to other exchanges. Internal exchanges are used to construct wiring that is not visible to applications.

declare-passive clj

(declare-passive ch name)

Performs a passive exchange declaration (checks if an exchange exists)

delete clj

(delete channel name)

(delete channel name if-unused)

Deletes an exchange using exchange.delete AMQP method. When an exchange is deleted all queue bindings on the exchange are cancelled.

Options: :if-unused If set, the server will only delete the exchange if it has no queue bindings. If the exchange has queue bindings the server does not delete it but raises a channel exception instead.

Usage example:

(lhe/delete channel exchange true)

direct clj

(direct channel name & opts)

Shortcut method for declaring direct exchange by using exchange.declare AMQP method

fanout clj

(fanout channel name & opts)

Shortcut method for declaring fanout exchange by using exchange.declare AMQP method

topic clj

(topic channel name & opts)

Shortcut method for declaring topic exchange by using exchange.declare AMQP method

unbind clj

(unbind channel destination source)

(unbind channel destination source routing-key)

(unbind channel destination source routing-key arguments)

Unbinds an exchange from another exchange using exchange.unbind AMQP method (a RabbitMQ-specific extension)