![Futures
A Future is an object holding a value which
may become available at some point.
!
•
A Future is either completed or not completed
•
A completed Future is either:
•
successful (value)
•
or failed (exception)
!
!
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent._
val fs: Future[String] = Future { “a” + “b” }
fs.onComplete {
case Success(x) => println(x)
case Failure(e) => throw e
}](https://image.slidesharecdn.com/anatomy-kickoff-140129153550-phpapp02/85/Anatomy-of-a-Reactive-Application-4-320.jpg)
![pipeTo
import akka.pattern.pipe
!
val future: Future[Any] = someFunctionReturningFuture()
future pipeTo sender // sends to sender as Future[Any]
!
// is roughly equivalent to
!
val mysender = sender // final def sender(): ActorRef
future.onComplete {
case Success(x) => mysender ! x
case Failure(e) => mysender ! akka.actor.Status.Failure(e)
}
!
// if sender doesn't handle Failure(e) it is logged as unhandled](https://image.slidesharecdn.com/anatomy-kickoff-140129153550-phpapp02/85/Anatomy-of-a-Reactive-Application-9-320.jpg)
Anatomy of a Reactive Application
- 1. Anatomy of a Reactive Application Reactive Programming Enthusiasts Denver Meet-up Kick-Off Mark Wilson
- 2. Demo Application Intended to Illustrate some concepts of Reactive Programming, Introduce: Scala Akka Play! but the demo is mostly about Non-Blocking
- 3. Amdahl’s Law “… Therefore it is important that the entire solution is asynchronous and non-blocking. ” - Reactive Manifesto
- 4. Futures A Future is an object holding a value which may become available at some point. ! • A Future is either completed or not completed • A completed Future is either: • successful (value) • or failed (exception) ! ! import scala.concurrent.ExecutionContext.Implicits.global import scala.concurrent._ val fs: Future[String] = Future { “a” + “b” } fs.onComplete { case Success(x) => println(x) case Failure(e) => throw e }
- 5. The Fish Store 1. Play GET and POST, non-blocking 2. Akka Actors processing a delivery Start from the start a most simple web page
- 6. Actor From the book “Akka Concurrency” by Derek Wyatt
- 7. Web Tier (Play) An open source web application framework, written in Scala and Java, which follows the model–view– controller architectural pattern. Stateless: horizontally scalable Aims to allow concurrency throughout the application Fits with REST/ powerful javascript
- 8. Akka Using the Actor Model we raise the abstraction level and provide a better platform to build correct, concurrent, and scalable applications. - akka docs From the book “Akka Concurrency” by Derek Wyatt
- 9. pipeTo import akka.pattern.pipe ! val future: Future[Any] = someFunctionReturningFuture() future pipeTo sender // sends to sender as Future[Any] ! // is roughly equivalent to ! val mysender = sender // final def sender(): ActorRef future.onComplete { case Success(x) => mysender ! x case Failure(e) => mysender ! akka.actor.Status.Failure(e) } ! // if sender doesn't handle Failure(e) it is logged as unhandled
- 10. Akka More.. Configuration Akka Test Kit Akka Extensions Akka Traits { Stash, ActorLogging } TypedActor Akka Events { EventBus, EventStream } - Pub/sub behavior Akka Scheduler - sending a message to an actor on a schedule. Super vision/Fault Tolerance { Resume, Restart, Stop, Escalate } Data Flows - special lib for writing futures: flow { “hi” } onComplete println Pipeline - sequential processing within an actor Remote Actors - utilizing actors on remote machines (or clustered machines)
- 11. “It is better to fail in originality than to succeed in imitation.” –Herman Melville
- 13. RPED Chunk-O-Thon One March 2014 Collective 3 minute presentations Open participation Topics span Reactive Applications Examples: Working examples / Shared learning exercise Well formed problem/question for the group Weird, funny or unexpected behavior Realtime UI tricks Other interesting stuff you come up with Submissions must be available 1 week prior to meeting There will be prizes!