How to structure a RESTful API with Spray.io?

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