Endpoints

To actually fetch some data, we will need to define our endpoints. That’s a piece of cake! (quite literally, we’ll use the cake pattern for our convenience). An endpoint is basically something with a Data type and a fetch method, which returns Future[Data]. Endpoints correspond directly to the external APIs. If there’s a REST API /webservice/api/books/#id, which returns JSON, we’ll have an endpoint with Data = JsValue and fetch using an HTTP client to download the respective url.

import resolvable._
import resolvable.json._
import resolvable.http._

trait Endpoints {

  // this logger just println-s the endpoints being fetched
  // great for debugging!
  val endpointLogger = EndpointLogger.println(success = true, failure = false)

  // Dispatch and Android clients are provided
  val httpClient = new DispatchClient

  // the base of our endpoints
  abstract class RemoteResource(val baseUrl: String) extends HttpJsonEndpoint {
    val id: String
    val logger = endpointLogger
    val client = httpClient
    protected def fetch(implicit ec: ExecutionContext) =
      client.getJson(s"$baseUrl/$id")
  }

  // an endpoint for our books
  case class RemoteBook1(id: String)
    extends RemoteResource("/webservice1/api/books")

  // another one
  case class RemoteBook2(id: String)
    extends RemoteResource("/webservice2/api/books")

  // an endpoint for our authors
  case class RemoteAuthor(id: String)
    extends RemoteResource("/webservice/api/authors")

}

In the same fashion we can add endpoints for other services or for local databases.