Responsible by interact with Rentbrella's Eventbus.

Configuration

Processing functions

The GenStage present in this application uses external functions for process the received messages.

Example bellow configures functions to process events user_blocked, movement_created and movement_returned:

config :lib_event_bus,
  callbacks: [
    {"user_blocked",      &MyApp.handle_user_blocked/1},
    {"movement_created",  &MyApp.handle_movement_created/1},
    {"movement_returned", &MyApp.handle_movement_returned/1}
  ],
  eventbus_module: Context.Module

These functions must be arity 1, and the argument passed in each call will be a %EventBus.SQSMessage{} struct.

Besides this, these functions must return :ok when received message is successfully processed, and :error when have a processing error. Any different return will cause exceptions and message will be returned for processing in future.

Application's architecture

Modules of this applications is grouped in three main roles:

Data structs

Contains structs which represent data exchanged between another modules. Note that structs in this group must be created using function new of corresponding module.

Queue interactions

Performs all interactions with queue, including publications, receivement and acknowledging of processed messages.

Note that functions in this group only implements basic functions for pontual queue's interactions.

For a constant SQS subscription, a GenStage was implemented in this library

GenStage modules

Implements a GenStage to process SQS messages.

The Producer will query SQS about new messages, ProducerConsumer will filter messages which system is not configurated to process, and the Consumer will perform a call for process function for each message received, passing the message processed as argument of this function.

When callback function returns :ok, the Consumer will acknowledge message, deleting it, so that it will not return for processing.

On the other hand, if this returns :error, the Consumer d'nt will acknowledge this, and the message will return to queue, to be consumed later.

More details, see section Processing functions