1. 1. Sandeep Purohit Software Consultant Knoldus Software LLP Sandeep Purohit Software Consultant Knoldus Software LLP
2. 2. Topics CoveredTopics Covered What is spray Why we use spray Spray application architecture Spray-can HTTP server Spray-routing Demo What is spray Why we use spray Spray application architecture Spray-can HTTP server Spray-routing Demo
3. 3. What is SprayWhat is Spray spray is an open-source toolkit for building REST/HTTP-based integration layers on top of Scala and Akka. Principles of spray :- Fully asynchronous, non-blocking Actor- and Future-based High-performance Lightweight Modular Testable
4. 4. Why we use sprayWhy we use spray To make RESTful web services REST should be used if it is very important for you to minimize the coupling between client and server components in a distributed application. This may be the case if your server is going to be used by many different clients that you do not have control over. Simply make a controller layer of MVC architecture
5. 5. Spray-can Http serverSpray-can Http server The spray-can HttpServer is scoped with a clear focus on the essential functionality of an HTTP/1.1 server: Connection management Message parsing and header separation Timeout management (for requests and connections) Response ordering (for transparent pipelining support) The spray-can HTTP server is implemented by two types of Akka actors, which sit on top of Akka IO. When you tell spray-can to start a new server instance on a given port an HttpListener actor is started, which accepts incoming connections and for each one spawns a new HttpServerConnection actor, which then manages the connection for the rest of its lifetime
6. 6. Starting spray-can Http serverStarting spray-can Http server // we need an ActorSystem to host our application in implicit val system = ActorSystem("spray-api-service") // create and start our service actor val service = system.actorOf(Props[MyServiceActor], "spray-service") // start a new HTTP server on port 8080 with our service actor as the handler IO(Http) ! Http.Bind(service, interface = "localhost", port = 8080) } A spray-can HTTP server is started by sending an Http.Bind command to the Http extension:
7. 7. Spray-routing The spray-routing module provides a high-level, very flexible routing DSL for elegantly defining RESTful web services. Normally you would use it either on top of a spray-can HTTP Server. Val routes = path("index") { get { respondWithMediaType(`text/html`) { complete { HttpResponse(OK, "Hello Sandeep ") } } } }
8. 8. Directives Directives are small building blocks of which you can construct arbitrarily complex route structures. Here is a simple example of a route built from directives: A directive does one or more of the following: Transform the incoming RequestContext before passing it on to its inner Route Filter the RequestContext according to some logic, i.e. only pass on certain requests and reject all others Extract values from the RequestContext and make them available to its inner Route as extractions Complete the request
9. 9. Composing directives val route: Route = path("order" / IntNumber) { id => get { complete { "Received GET request for order " + id } } ~ put { complete { "Received PUT request for order " + id } } } you can also use the | operator on directives Get and put directives are chained together with the ~ operator to form a higher-level route that serves as the inner Route of the path directive
10. 10. Parameters .? (optional) ? "red" (default value) ! "blue" (color should be blue) .as[Int] (deserialize as a Int) Query parameters can be either extracted as a String or can be converted to another type. The parameter name can be supplied either as a String or as a Symbol. Parameter extraction can be modified to mark a query parameter as required or optional or to filter requests where a parameter has a certain value
11. 11. Get request parameters extract val route = parameters('color, 'backgroundColor) { (color, backgroundColor) => complete(s"The color is '$color' and the background is '$backgroundColor'") } Deserialize the parameters val route = parameters('color, 'count.as[Int]) { (color, count) => complete(s"The color is '$color' and you have $count of it.") }
12. 12. Marshalling Marshalling is the process of converting a higher-level (object) structure into some kind of lower-level representation, often a wire format. Other popular names for it are Serialization or Pickling. In spray Marshalling means the conversion of an object of type T into an HttpEntity spray-httpx comes with pre-defined Marshallers for the following types: Array[Byte] Array[Char] String Option[T] Either[A, B] Try[T] Future[T]
13. 13. Unmarshalls Entity Directive The entity directive works in conjuction with as and spray.httpx.unmarshalling to convert some serialized wire format value into a higher-level object structure val route = post { entity(as[Person]) { person => complete(s"Person: ${person.name} - favorite number: $ {person.favoriteNumber}") } }
14. 14. Spray test-kit For services built with spray-routing spray provides a dedicated test DSL that makes actor-less testing of route logic easy and convenient. This route test DSL is made available with the spray-testkit module. "return a 'PONG!' response for GET requests to /ping" in { Get("/ping") ~> smallRoute ~> check { responseAs[String] === "PONG!" } }
15. 15. Thank you