Modern web applications that are always connected require a new kind of architecture to handle real-time streaming of data. They require a reactive architecture that is event-driven and resilient to failures. But how hard are these applications to actually build? In this presentation we will learn just how easy it can be to build a reactive application using Play and Akka. The application will use Play to asynchronously read from a web service and stream it to the client using Websockets and JSON. In building this sample you will learn the basics of how a Play application is structured and how it integrates with Akka for building reactive applications.

1. REACTIVE WITH PLAY AND AKKA
Markus Jura

2. ABOUT ME
Consultant
@Typesafe
Living in Hamburg
Co-Founder of
testmunk
3 years Scala, 10 years Java background
Follow @markusjura Follow @markusjura 233 followers

3. REACTIVE APPS
reactivemanifesto.org

4. Productivity
Scalable
Modern web & mobile

5. ROUTES
VERB PATH CONTROLLER_METHOD
GET / controllers.Application.index()
GET /foo controllers.Application.foo()
Declarative, type-safe URL Mapping

6. CONTROLLERS
public static Result index() {
return ok("Hello World!");
}

7. ASYNCHRONOUS REQUEST
import play.libs.F.*;
private static Integer calc() {
return (5134 * 5789) / 349;
}
public static Promise<Result> basicPromise() {
Promise<Integer> promise = Promise.promise(() -> calc());
return promise.map(i -> ok("Result is: " + i));
}

8. HTTP REQUEST
public static Promise<Result> getPage() {
final Promise<WSResponse> promise =
WS.url("http://google.com").get();
return promise.map(response -> ok(response.getBody()));
}

9. CONCURRENT HTTP REQUESTS
public static Promise<Result> composition() {
final Promise<WSResponse> googlePromise =
WS.url("http://google.com").get();
final Promise<WSResponse> twitterPromise =
WS.url("http://twitter.com").get();
return googlePromise.flatMap(google ->
twitterPromise.map(twitter ->
ok(google.getBody() + twitter.getBody())));
}

10. WEBSOCKETS OVERVIEW

11. WEBSOCKETS CLIENT CODE
ws = new WebSocket("ws://url/echo")
ws.onmessage = (event) ->
alert(event.data)
ws.onopen = () ->
ws.send("Echo")
CoffeeScript

12. WEBSOCKETS SERVER CODE
public static WebSocket<JsonNode> echo() {
return WebSocket.whenReady((in, out) -> {
in.onMessage(out::write);
in.onClose(() -> Logger.debug("Connection closed"));
});
}
Play Controller

13. Single unified programming model for
Simpler concurrency
Simpler distribution
Simpler fault tolerance

14. SIMPLER CONCURRENCY
Actors let us write code in a single-threaded illusion
No locks, synchronized or other primitives needed

15. SIMPLER DISTRIBUTION
Everything in Akka is distributed by default
Akka goes from remote to local by optimization

16. SIMPLER FAULT TOLERANCE
Akka decouples communication from failure handling:
Supervisors handle failure
Callers need not care (they can't anyway)

17. REACTIVE STOCKS ARCHITECTURE

18. Demo

19. THANK YOU
Slide Deck on
Reactive Stocks
Github
Activator Template
Follow @markusjura Follow @markusjura 233 followers