Spray REST API Application Structure - Suggestions Needed - scala

Question

I have the following multi-module project structure built using sbt:
myProject-api
myProject-core
myProject-core is organized as below:
It contains certain actors which acts as a facade to my services. For example., I have a UserActor that sits in front of a UserService. A NotificationActor that sits in front of a NotificationService and so on.
I have another trait that exposes there actors to anybody that is interested:
trait MyProjectCoreActors {
def myAppCfg = MyProjConfig.appCfg
def userActor = myAppCfg.userActor
def notifyActor = myAppCfg.notifyActor
}
object MyProjectCoreActors {
... some initialization routing that initializes the MyProjConfig
}
My UserActor is thus defined as:
class UserActor(service: UserService) extends Actor {
...
...
}
My UserService is as follows:
class UserService(dbConfig: DbConfig) {
...
...
}
I have another class called MyProjectConfig which I initialize using the application.conf file. In this file I have the connection details to the database and so on. The MyProjectConfig is initialized as below:
trait MyProjectConfig {
def actorSystem: ActorSystem
// the actors
def userActor: ActorRef
}
object MyProjectConfig {
def apply(appConfig: Config, system: ActorSystem): MyProjectConfig = {
new MyProjectConfig {
private val dbConfig = loadDBConfig(appConfig)
override val actorSystem = system
// each actor gets its own DBConfigInstance instance
override val userActor =
actorSystem.actorOf(
Props(new UserActor(UserService(dbConfig)))
)
}
}
}
I have now the Spray routing as defined below:
trait MyProjectService extends HttpService with MyProjectCoreActors {
def pingRoute = path("ping") {
get {
userActor ! "newUser"
complete("pong!")
}
}
def pongRoute = path("pong") {
get { complete("pong!?") }
}
def route = pingRoute ~ pongRoute
}
What is now missing is a way to call the MyProjectConfig.apply(....) method and pass in the Actor System and the underlying application.conf!
This was originally a Play based application, where I had a Lifecycle plug in which had access to the underlying Application from where I got the config and the actor system. How could I now get the same here with Spray?
I have a Boot class that looks like this:
object MyBootHttpService extends App {
implicit val actorSystem = ActorSystem("myproj-actor-system")
}
How could I pass this ActorSytem to MyProjectConfig.apply(....)? and from where could I get the application.conf?

Answer 1

I think you can do such things (DI) in your MyBootHttpService class.
For example
object MyBootHttpService extends App {
implicit val actorSystem = ActorSystem("myproj-actor-system")
private val config = ConfigFactory.load
private val myAppConfig = MyProjectConfig(config, actorSystem)
// Initialise classes that depend on config and actorsystem....
private val service = new MyProjectService with HttpServiceActor {
override implicit val actorRefFactory = actorSystem
}
// Bind our service
IO(Http) ? Bind(listener = service, interface = "0.0.0.0", port = config.getInt("port"))
}
Typesafe config library object ConfigFactory is generally used to load config files. ConfigFactory.load with no args will try and load application.conf from the classpath.