langohr.exchange
bind
(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
(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
(declare-passive ch name)
Performs a passive exchange declaration (checks if an exchange exists)
delete
(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
(direct channel name & opts)
Shortcut method for declaring direct exchange by using exchange.declare AMQP method
fanout
(fanout channel name & opts)
Shortcut method for declaring fanout exchange by using exchange.declare AMQP method
topic
(topic channel name & opts)
Shortcut method for declaring topic exchange by using exchange.declare AMQP method
unbind
(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)