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![Scala — JSON Writes example
33
• Simply define a Writes in
implicit scope before invoking
toJson
implicit val locationWrites = new Writes[Location] {!
def writes(location: Location) = Json.obj(!
"lat" -> location.lat,!
"long" -> location.long!
)!
}!
!
val json = Json.toJson(location)](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/85/Play-Framework-and-Activator-33-320.jpg)
![Scala — JSON Reads example
• Also elegantly handles Reads
• Build in validate using standard
types (e.g, Double, Int, etc) or
define your own validators
34
implicit val locationReads: Reads[Location] = (!
(JsPath "lat").read[Double] and!
(JsPath "long").read[Double]!
)(Location.apply _)!
!
val json = { ... }!
!
val locationResult: JsResult[Location] = !
! json.validate[Location]](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/85/Play-Framework-and-Activator-34-320.jpg)
![WebSockets
def websocketAction = WebSocket.acceptWithActor[JsValue, JsValue] { request => channel =>!
! SomeActor.props(channel)!
}!
40
• Play provides two different built in mechanisms for handling WebSockets
• Actors — better for discreet messages
• Iteratees — better for streams
• Both of these mechanisms can be accessed using the builders provided on WebSocket](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/85/Play-Framework-and-Activator-40-320.jpg)
![Scala — JSON Writes example
33
• Simply define a Writes in
implicit scope before invoking
toJson
implicit val locationWrites = new Writes[Location] {!
def writes(location: Location) = Json.obj(!
"lat" -> location.lat,!
"long" -> location.long!
)!
}!
!
val json = Json.toJson(location)](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/75/Play-Framework-and-Activator-33-2048.jpg)
![Scala — JSON Reads example
• Also elegantly handles Reads
• Build in validate using standard
types (e.g, Double, Int, etc) or
define your own validators
34
implicit val locationReads: Reads[Location] = (!
(JsPath "lat").read[Double] and!
(JsPath "long").read[Double]!
)(Location.apply _)!
!
val json = { ... }!
!
val locationResult: JsResult[Location] = !
! json.validate[Location]](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/75/Play-Framework-and-Activator-34-2048.jpg)
![WebSockets
def websocketAction = WebSocket.acceptWithActor[JsValue, JsValue] { request => channel =>!
! SomeActor.props(channel)!
}!
40
• Play provides two different built in mechanisms for handling WebSockets
• Actors — better for discreet messages
• Iteratees — better for streams
• Both of these mechanisms can be accessed using the builders provided on WebSocket](https://image.slidesharecdn.com/play-activator-webinar-140910190235-phpapp02/75/Play-Framework-and-Activator-40-2048.jpg)
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Play Framework and Activator
- 1. Play Framework andActivator Getting started with the Play Framework with Activator
- 2. Topics, goals, context 2 • An introduction to Typesafe Activator • An introduction to the core features of Play 2.x • What is a Reactive application, and how do you build one with Play?
- 3. Introduction to TypesafeActivator
- 4. “Typesafe Activator isa browser-based or command-line tool that helps developers get started with the Typesafe Reactive Platform.”
- 5. Getting started withthe Typesafe Activator UI 5 • Download Typesafe Activator • https://typesafe.com/platform/getstarted • Optional (Mac) • ~ $ rm -R .sbt • ~ $ rm -R .ivy • Unarchive and execute (Mac) • $ ./activator ui
- 6. Activator tutorials andseeds 6
- 7. Activator Overview 7 • Learn — In depth tutorials • Develop — Code, compile, test, run, inspect • Deliver — Monitoring integration with AppDynamics and New Relic
- 8. Code view 8 • Activator • Browse code • Make small changes • IDE • Generate IDEA or Eclipse project files • Dig into the template in your favourite IDE
- 9. Development monitoring 9 • Incoming requests • Controller • HTTP verb (GET, POST, etc) • Response code • Invocation time
- 10. Inspect — Developmentmonitoring 10 • Actor metrics • Throughput — messages/s • Max time — high watermark • Max size — mailbox
- 11. Monitoring and support 11 • Application monitoring • Need production caliber monitoring? • AppDynamics or New Relic integration • Support • Ready to take your application to the next level? • http://typesafe.com/how/subscription
- 12. Contributing a template— tutorials vs seeds 12 • Seed • Boilerplate code as a starting point • Tutorial • Teaching about a particular focused topic or integration • Components • Activator templates are just regular sbt projects with some additional components • Metadata (activator.properties), license, sbt build file, tutorial (tutorial/index.html) • Contribute! • https://typesafe.com/activator/template/contribute
- 13. The Typesafe ActivatorUI is a Play framework application. ! Peek behind the covers… ! https://github.com/typesafehub/activator/tree/master/ui
- 14. Play 2.3 overview 14 • Stateless MVC framework with routing, a template engine, REST support, etc • Dynamic class reloading • Support for Java 8 and Scala 2.1x • sbt-web to implement an asset pipeline • Akka interoperability for highly concurrent web applications • Built on Netty 3.9.x
- 15. Play application overview 15 View Controller JSON Model Slick JPA WS DB Akka Network
- 16.
- 17. 17 Simplified HTTPrequest 1. mydomain.com/admin/settings renders views.html.admin HTML 2. Browser fetches static assets served from outside of Play 3. Ajax requests — Play serves JSON via a RESTful API Browser Play HTTP GET (mydomain.com/admin/settings) HTML for views.html.admin(...) CDN JS, CSS, images, etc HTTP GET (mydomain.com/ws/some/services) JSON
- 18. Example template withAngularJS 18 @(customer: Customer)! ! <head>...</head>! <body>! <div class="wrapper">! <header>…</header>! <h1>Welcome @customer.name!</h1>! <section id="body" ng-app="ngAdmin">! <div ng-view></div>! </section>! <footer>...</footer>! </div>! </body>! </html> load async || fail whale • Scala template rendered by Twirl and returned by Play controller Header Play handles navigation Footer • HTML inserted into ng-view by Angular controller after initial page render load async || omit AngularJS
- 19. Creating your firstroutes and controllers
- 20. routes 20 GET!/admin!! ! ! ! controllers.AdminController.index! GET ! /admin/login! ! ! controllers.AdminController.login! GET ! /admin/*any! ! ! controllers.AdminController.angularWildcard(any: String)! GET ! /ws/some/service! ! controllers.ServiceController.service • Routes must be declared in order • /admin and /admin/login are used to render Scala view templates • /admin/*any will be intercepted by client-side routing in AngularJS • Client-side routes may hit the server if the URI has been bookmarked • Nothing special about web services aside from payload (JSON vs HTML)
- 21. Sample controller action 21 /**! * Renders the admin template.! */! def index = Action.async {! implicit request =>! val account = loggedIn! Ok(views.html.admin()).withCookies(Cookie(“…”, …, httpOnly = false))! } • Controllers should stay thin and delegate the real work • Controllers actions should always be async • Controllers are stateless so context must be stored in cookies or cached
- 22. Asynchronous vs synchronousprocessing times 22 Asynchronous - 200ms Process 1 Process 2 75 ms Process 3 200 ms 150 ms 0 ms 425 ms Synchronous - 425ms Process 1 Process 2 Process 3 0 ms 425 ms • Staying async — and in the future — ensures that processing time is not bounded by IO • Async processing is limited by only the longest running process • Synchronous processing is limited by the combined processing times • Stay async!
- 23. Asset pipeline andsbt-web
- 24. An intro tosbt-web 24 • sbt-web brings the notion of a highly configurable asset pipeline to build files pipelineStages := Seq(rjs, digest, gzip)! • The above will order the RequireJs optimizer (sbt-rjs), the digester (sbt-digest) and then compression (sbt-gzip) • These tasks will execute in the order declared, one after the other
- 25. Asset pipelines 25 • Example asset pipeline • source file → • step 1: linting → • step 2: uglification/minification → • step 3: fingerprinting → • step 4: concatenation (optional)
- 26. Asset pipelines 26 • Linting • Inspect source code for suspicious language usage • Uglification/minification • Mangle and compress source files, e.g, remove whitespace, etc • Fingerprinting • Change the filename to reflect the contents of the file for cache busting • Concatenation • Combine multiple source files to reduce browser load times
- 27. sbt-web and assetfingerprinting 27 • Asset fingerprinting makes the name of a file dependent on the contents of the file • HTTP headers can be set to encourage caches to keep their own copy of the content • When the content is updated, the fingerprint will change • This will cause the remote clients to request a new copy of the content • Known as cache busting
- 28. Turning on assetfingerprinting 28 • Turning on asset fingerprinting only requires one additional route GET /assets/*file! controllers.Assets.versioned(path="/public", file: Asset) • Then request each asset as versioned <link rel="stylesheet" href=“@routes.Assets.versioned('assets/images/example.png')"> • A digest file and new file will be created based on MD5 ./target/web/digest/images/23dcc403b263f262692ac58437104acf-example.png! ./target/web/digest/images/example.png.md5
- 29. sbt-web plugins 29 • sbt-coffeescript • sbt-concat • sbt-css-compress • sbt-digest • sbt-filter • sbt-gzip • sbt-handlebars • sbt-html-minifier • sbt-imagemin • sbt-jshint • sbt-jst • sbt-less • sbt-mocha • sbt-purescript • sbt-reactjs • sbt-rjs • sbt-stylus • sbt-uglify
- 30. Model-tier and dataaccess
- 31. Model-tier considerations 31 Think in verbs rather than nouns… • save(model) • SRP — save is likely a simple function that does a single thing • model.save() • Violates SRP — tougher to test • Play makes it easy to implement your preferred solution to persistence • CRUD, CQRS (Command Query Responsibility Segregation), etc
- 32. Scala — Slickexample 32 // This code:! coffees.filter(_.price < 10.0).map(_.name)! ! // Will produce a query equivalent to the following SQL:! select COF_NAME from COFFEES where PRICE < 10.0 • Slick is a Functional Relational Mapping (FRM) library for Scala where you work with relational data in a type-safe and functional way • Developers benefit from the type-safety and composability of FRM as well as being able to reuse the typical Scala collection APIs like filter, map, foreach, etc • Can also use plain SQL for insertions, complex joins, etc • http://typesafe.com/activator/template/hello-slick-2.1
- 33. Scala — JSONWrites example 33 • Simply define a Writes in implicit scope before invoking toJson implicit val locationWrites = new Writes[Location] {! def writes(location: Location) = Json.obj(! "lat" -> location.lat,! "long" -> location.long! )! }! ! val json = Json.toJson(location)
- 34. Scala — JSONReads example • Also elegantly handles Reads • Build in validate using standard types (e.g, Double, Int, etc) or define your own validators 34 implicit val locationReads: Reads[Location] = (! (JsPath "lat").read[Double] and! (JsPath "long").read[Double]! )(Location.apply _)! ! val json = { ... }! ! val locationResult: JsResult[Location] = ! ! json.validate[Location]
- 35. Futures, Actors, andWebSockets
- 36. “If you wantto parallelize a very deterministic algorithm, futures are the way to go.” - Derek Wyatt, Akka Concurrency
- 37. Futures 37 defindex = Action.async {! ! val futureInt = scala.concurrent.Future { intensiveComputation() }! ! futureInt.map(i => Ok("Got result: " + i))! } • Great for handling immutable state • Intensive computations, reading from a database, pulling from web services, etc • Composition — futures guarantee order when chained • Parallelizing a deterministic algorithm
- 38. “Add behaviour toan algorithm by inserting actors into the message flow.” - Derek Wyatt, Akka Concurrency
- 39. Actors • Greatfor handling mutable state • Easy for imperative developers to dive into quickly • Don't guarantee order • Easy to change behaviour by inserting new actors into the message flow • Messages are directed to a specific actor, avoiding callback hell 39 package actors! ! import akka.actor._! ! object SomeActor {! ! def props = Props(new GameActor)! }! ! class SomeActor extends Actor {! ! def receive = {! ! ! case request: SomeRequest => {! ! ! ! sender ! SomeResponse(...) ! ! ! }! ! }! }!
- 40. WebSockets def websocketAction= WebSocket.acceptWithActor[JsValue, JsValue] { request => channel =>! ! SomeActor.props(channel)! }! 40 • Play provides two different built in mechanisms for handling WebSockets • Actors — better for discreet messages • Iteratees — better for streams • Both of these mechanisms can be accessed using the builders provided on WebSocket
- 41.
- 42. Test framework comparison 42 • ScalaTest • Human readable output — in English • FeatureSpec • Matchers • http://www.artima.com/docs-scalatest-2.0.M8/#org.scalatest.Matchers • Great writeup by Gilt • http://tech.gilt.com/post/62430610230/which-scala-testing-tools-should-you-use
- 43. Test framework comparison 43 • Specs2 • Enabled by default in Play • Good choice for international teams who gain less from English readability • Both Specs2 and ScalaTest are fantastic!
- 44. Coming soon toPlay 2.4
- 45. Play 2.4 45 • Built-in dependency injection support • Experimental support for running Play on akka-http • Experimental support for handling IO in Java and Scala using Reactive Streams • Slick over anorm, JPA over ebean • Pull anorm/ebean support out into separate modules in GitHub playframework repo
- 46.
- 47. ©Typesafe 2014 –All Rights Reserved