WA9ACE / mqrouter

MQRouter

This gem is for use in our ruby apps for communicating with other microservices over a rabbitmq server.

Usage

Required ENV Vars

RABBIT_URL # example "amqps://username:[e-mail]/something"

Message Handlers

Message Handlers will define a queue they want to watch on a given exchange and for a rails app should be placed in

app/queue/

An example handler would look like this:

class ExampleQueue < MQRouter::MessageHandler
  # watch takes the exchange, routing key, and an optional queue name 
  watch 'activity', 'codex.translate'

  # Each handler needs a receive method that will be called when new data is available
  def receive(packet)
    begin
      some_payload = Danger.do_some_risky_thing msg
      respond_with result(some_payload, 202) // The second parameter is an optional status code
    rescue Exception => ex
      respond_with error(ex)
    end
  end
end

Methods

respond_with(packet, opts={}) takes a packet, automatically sets the correlation_id and routing_key if available, then ships it out to the queue. opts can be used to send your own options to the the underlying bunny library and override defaults.

result(data, status_code=200) returns a packet that can be handed to respond_with. It takes an object of what you want to be the body of your packet and an optional status_code.

error(data, status_code=500) returns a packet that can be handed to respond_with. It takes an object of what you want to be the body of your packet and an optional status_code. It also automatically sends the error packet over the error exchange to the corresponding queue.

Responding to an RPC call is automatically handled by MQRouter. You don't need to worry about managing responses. You simply call respond_with a result or an error. The first parameter is the data that will be shipped back in the body: field of the response. The second parameter is an optional status_code. The default for result is 200 and the default for error is 500. To override these just provide a second parameter.

The error method will automatically handle wrapping the error and reporting it back to the calling application if it's waiting for a response, and piping it out to the error queue.