vent

An application that simplifies writing RabbitMQ producers and consumers.

Typically, a client workflow is as follows:

• Establish a connection to a broker
• Create a new channel within the open connection
• Execute AMQP commands with a channel such as sending and receiving messages, creating exchanges and queue or defining routing rules between exchanges and queues
• When no longer required, close the channel and the connection

Vent encapsulates this workflow and delegates the consumer specific-logic to a custom handler behaviour.

Configuration

RabbitMQ configuration:

{host, "localhost"},                                # defaults to 'localhost'
{port, 5672},                                       # defaults to 5672
{username, "user"},                                 # optional
{password, "pass"},                                 # optional
{virtual_host, <<"prod">>},                         # required
{publish_exchange, <<"publish_exchange">>}          # required

Publishers

Only one topic exchange message flow is currently supported. Also, it is not possible to configure multiple publishers at present. The serialization format is assumed to be JSON.

Publisher configuration:

{publish_exchange, <<"publish_exchange">>}          # required
{publish_chunk_size, 20}                            # defaults to 20

Subscribers

A subscriber handler should be created for every subscription. The behaviour consists of the following callbacks:

callback init() ->
   {ok, state()}.
callback handle(term(), state()) ->
   {ok, state()} |
   {requeue, term(), state()} |
   {drop, term(), state()}.
callback terminate(state()) ->
   ok.

An inert vent_debug_handler is already provided that will log every message that it consumes.

Every subscription should be configured together with its handler:

{n_workers, 1},                                     # defaults to 5
{prefetch_count, 2},                                # defaults to 2
{exchange, <<"exchange">>},                         # required
{dead_letter_exchange, <<"dl_exchange">>},          # required
{error_exchange, <<"errors">>},                     # required
{error_routing_key, <<"error_routing_key">>},       # required
{queue, <<"vent:queue">>},                          # required
{message_ttl, 300000},                              # defaults to 300000
{handler, vent_debug_handler}]                      # defaults to vent_debug_handler

Note that more than one subscriber may be registered.

 {subscribers,
     [{vent_subscriber, ...config for 1st subscriber},
      {vent_subscriber, ...config for 2nd subscriber}]}

Build

$ rebar3 compile

In order to run tests...{to do}

Release

$ rebar3 release