How to structure a RESTful API with Spray.io? - scala

Question

When I'm using Spray.io to develop a RESTful API, how should I structure my application?
I already saw this answer on how to split a Spray application, but I'm not satisfied with it, since it doesn't seem to use the "one actor per request" approach. Can I forward requests from the root actor to other actors in my application based on paths and, inside these actors, define the related routes?
Thanks

Answer 1

You can certainly forward requests from one actor to another, based on paths or whatever else. Check out my example project (which is a fork of a fork of an example project):
https://github.com/gangstead/spray-moviedb/blob/master/src/main/scala/com/example/routes/ApiRouter.scala
Relavent code from the main actor that receives all requests and routes them to other actors that handle each service:
def receive = runRoute {
compressResponseIfRequested(){
alwaysCache(simpleCache) {
pathPrefix("movies") { ctx => asb.moviesRoute ! ctx } ~
pathPrefix("people") { ctx => asb.peopleRoute ! ctx }
} ~
pathPrefix("login") { ctx => asb.loginRoute ! ctx } ~
pathPrefix("account") { ctx => asb.accountRoute ! ctx }
}
}
And for example the movies route:
def receive = runRoute {
get {
parameters('query, 'page ? 1).as(TitleSearchQuery) { query =>
val titleSearchResults = ms.getTitleSearchResults(query)
complete(titleSearchResults)
}~
path(LongNumber) { movieId =>
val movie = ms.getMovie(movieId)
complete(movie)
}~
path(LongNumber / "cast") { movieId =>
val movieCast = ms.getMovieCast(movieId)
complete(movieCast)
}~
path(LongNumber / "trailers") { movieId =>
val trailers = ms.getTrailers(movieId)
complete(trailers)
}
}
}

Answer 2

I was struggling a lot with creating first full REST project. The examples I've found was on hello world level... I've read few blogs, few comments and I decided to create example project. It is based on scala/akka/spray/mysql
It full working example with websocket to notify clients that data was changed etc. You can check it out on https://github.com/vixxx123/scalasprayslickexample
Here is sample code of routing from that project:
val personCreateHandler = actorRefFactory.actorOf(RoundRobinPool(2).props(Props[CreateActor]), s"${TableName}CreateRouter")
val personPutHandler = actorRefFactory.actorOf(RoundRobinPool(5).props(Props[UpdateActor]), s"${TableName}PutRouter")
val personGetHandler = actorRefFactory.actorOf(RoundRobinPool(20).props(Props[GetActor]), s"${TableName}GetRouter")
val personDeleteHandler = actorRefFactory.actorOf(RoundRobinPool(2).props(Props[DeleteActor]), s"${TableName}DeleteRouter")
val userRoute =
pathPrefix("person") {
pathEnd {
get {
ctx => personGetHandler ! GetMessage(ctx, None)
} ~
post {
entity(as[Person]) {
entity =>
ctx => personCreateHandler ! CreateMessage(ctx, entity)
}
}
} ~
pathPrefix (IntNumber){
entityId => {
pathEnd {
get {
ctx => personGetHandler ! GetMessage(ctx, Some(entityId))
} ~ put {
entity(as[Person]) { entity =>
ctx => personPutHandler ! PutMessage(ctx, entity.copy(id = Some(entityId)))
}
} ~ delete {
ctx => personDeleteHandler ! DeleteMessage(ctx, entityId)
} ~ patch {
ctx => personPutHandler ! PatchMessage(ctx, entityId)
}
}
}
}
}
And sample from create actor handler:
override def receive: Receive = {
case CreateMessage(ctx, person) =>
val localCtx = ctx
connectionPool withSession {
implicit session =>
try {
val resId = PersonsIdReturning += person
val addedPerson = person.copy(id = Some(resId.asInstanceOf[Int]))
localCtx.complete(addedPerson)
publishAll(CreatePublishMessage(TableName, localCtx.request.uri + "/" + addedPerson.id.get, addedPerson))
L.debug(s"Person create success")
} catch {
case e: Exception =>
L.error(s"Ups cannot create person: ${e.getMessage}", e)
localCtx.complete(e)
}
}
}
There are still two important things missing: oauth2 and push notifications to specific user/connection via websocket