Hanami 2.0 Ideas

proposals
9

Events/Instrumentation

Introduce an events system that can provide an API to emit/handle them. The system is similar to ActiveSupport::Notifications, and it should use wisper gem.

The idea is to “broadcast” an event happening in the framework or in a Hanami project and let the other part of the system to react to it. There are several scenarios.

Pub/Sub

class WelcomeMailer
  subscribe_to "user.signup"
end

class DripAdapter
  subscribe_to "user.signup"
end

class Signup
  include Hanami::Interactor

  def call(data)
    user = UserRepository.new.create(data[:user])
    broadcast("user.signup", user: user)
  end
end

When that event is emitted, WelcomeMailer and DripAdapter will receive a notification and react accordingly.

Async Execution

Continuing on the previous example, the broadcast is immediate, but the execution of the receiver logic can be async. We can send to a queue system (eg. sidekiq) the name of the event and the payload and let it to schedule the execution.

The API could be

broadcast("user.signup", user: user).async(...)

Instrumentation

def render
  broadcast('rendering.template') do
    # ...
  end
end

This reports the elapsed time. We can use it to log when a template was rendered.

This can be part of 1.x series.

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