lapin

v0.2.0

lapin v0.2.0 Lapin.Connection behaviour View Source

RabbitMQ connection handler

This module handles the RabbitMQ connection. It also provides a behaviour for worker module implementation. The worker module should use the Lapin.Connection behaviour and implement the callbacks it needs.

When using the Lapin.Connection behaviour a publish/4 function is injected in the worker module as a shortcut to the Lapin.Connection.publish/5 function which removes the need for passing in the connection and is publicly callable to publish messages on the connection configured for the implementing module.

Link to this section Summary

Types

config()

Connection configuration

on_callback()

Callback result

on_deliver()

handle_deliver/2 callback result

reason()

Reason for message rejection

t()

Connection

Functions

close(connection)

Closes the connection

publish(connection, exchange, routing_key, payload, options \\ [])

Publishes a message to the specified exchange with the given routing_key

start_link(configuration, options \\ [])

Starts a Lapin.Connection with the specified configuration

Callbacks

handle_cancel(arg0)

Called when receiving a basic.cancel from the broker

handle_cancel_ok(arg0)

Called when receiving a basic.cancel_ok from the broker

handle_consume_ok(arg0)

Called when receiving a basic.consume_ok from the broker

handle_deliver(arg0, arg1)

Called when receiving a basic.deliver from the broker

handle_publish(arg0, arg1)

Called when completing a basic.publish with the broker

handle_return(arg0, arg1)

Called when receiving a basic.return from the broker

payload_for(arg0, arg1)

Called before handle_deliver/2 to get the payload type

Link to this section Types

Link to this type config() View Source 
config() :: [{:channels, [Lapin.Channel.config()]}]

Connection configuration

The following keys are supported:

  • module: module using the Lapin.Connection behaviour
  • host: broker hostname (string | charlist), default: ‘localhost’
  • port: broker port (string | integer), default: 5672
  • virtual_host: broker vhost (string), default: “”
  • username: username (string)
  • password: password (string)
  • auth_mechanisms: broker auth_mechanisms ([:amqplain | :external | :plain]), default: amqp_client default
  • ssl_options: ssl options ([:ssl:ssl_option]), default: none
  • channels: channels to configure ([Channel.config]), default: []
Link to this type on_callback() View Source 
on_callback() :: :ok | {:error, message :: String.t()}

Callback result

Link to this type on_deliver() View Source 
on_deliver() :: :ok | {:reject, reason()} | term()

handle_deliver/2 callback result

Link to this type reason() View Source 
reason() :: term()

Reason for message rejection

Link to this section Functions

Link to this function close(connection) View Source 
close(connection :: t()) :: nil

Closes the connection

Link to this function publish(connection, exchange, routing_key, payload, options \\ []) View Source 
publish(connection :: t(), Lapin.Channel.exchange(), Lapin.Channel.routing_key(), Lapin.Message.Payload.t(), options :: Keyword.t()) :: on_callback()

Publishes a message to the specified exchange with the given routing_key

Link to this function start_link(configuration, options \\ []) View Source 
start_link(config(), options :: GenServer.options()) :: GenServer.on_start()

Starts a Lapin.Connection with the specified configuration

Link to this section Callbacks

Link to this callback handle_cancel(arg0) View Source 
handle_cancel(Lapin.Channel.t()) :: on_callback()

Called when receiving a basic.cancel from the broker.

Link to this callback handle_cancel_ok(arg0) View Source 
handle_cancel_ok(Lapin.Channel.t()) :: on_callback()

Called when receiving a basic.cancel_ok from the broker.

Link to this callback handle_consume_ok(arg0) View Source 
handle_consume_ok(Lapin.Channel.t()) :: on_callback()

Called when receiving a basic.consume_ok from the broker.

This signals successul registration as a consumer.

Link to this callback handle_deliver(arg0, arg1) View Source 
handle_deliver(Lapin.Channel.t(), Lapin.Message.t()) :: on_deliver()

Called when receiving a basic.deliver from the broker.

Return values from this callback determine message acknowledgement:

  • :ok: Message was processed by the consumer and should be removed from queue
  • {:reject, reason}: Message was not processed and should be rejected

Any other return value requeues the message to prevent data loss. A crash in the callback code will however reject the message to prevent loops if the message was already delivered before.

The reason term can be used by the application to signal the reason of rejection and is logged in debug.

Link to this callback handle_publish(arg0, arg1) View Source 
handle_publish(Lapin.Channel.t(), Lapin.Message.t()) :: on_callback()

Called when completing a basic.publish with the broker.

Message transmission to the broker is successful when this callback is called.

Link to this callback handle_return(arg0, arg1) View Source 
handle_return(Lapin.Channel.t(), Lapin.Message.t()) :: on_callback()

Called when receiving a basic.return from the broker.

This signals an undeliverable returned message from the broker.

Link to this callback payload_for(arg0, arg1) View Source 
payload_for(Lapin.Channel.t(), Lapin.Message.t()) :: Lapin.Message.Payload.t()

Called before handle_deliver/2 to get the payload type.

Should return a data type instance to decode the payload into. A Lapin.Message.Payload implementation must be provided for this type. The default implementation leaves the payload unaltered.