Many times, our business logic dictates that we need to perform a redirect from a certain page to another if various conditions match. For these, we can subscribe to the request event and simply change the response, essentially bypassing the normal process, which would have gone through all the layers of Drupal. However, before we see an example, let's talk about the Event Dispatcher for just a bit.
The central player in this system is the event_dispatcher service, which is an instance of the ContainerAwareEventDispatcher class. This service allows the dispatching of named events that take a payload in the form of an Event object, which wraps the data that needs to be passed around. Typically, when dispatching ...
