An application's life cycle has two states: running and stopped. These are times when the state of the application changes. At times, we need to perform some operations right before or after a state change has occurred or is about to occur.

Play applications use a Netty server. For this, a class with the same name is used. It is defined as follows:

class NettyServer(appProvider: ApplicationProvider, port: Option[Int], sslPort: Option[Int] = None, address: String = "0.0.0.0", val mode: Mode.Mode = Mode.Prod) extends Server with ServerWithStop { … }

This class is responsible for binding or bootstrapping the application to the server.

The ApplicationProvider trait is defined as follows:

trait ApplicationProvider {
  def path: File
  def get: Try[Application]
  def handleWebCommand(requestHeader: play.api.mvc.RequestHeader): Option[Result] = None
}

An implementation of ApplicationProvider must create and initialize an application. Currently, there are three different...