Building APIs in Scala with Play! Framework 2 Silicon Valley Code Camp Oct 5th, 2013 Manish Pandit @lobster1234 

Manish Pandit @lobster1234 mpandit@netflix.com linkedin.com/in/mpandit slideshare.net/lobster1234 

Agenda Scala Typesafe Platform PlayFramework REST Hands-on API Open Floor 

Scala Concise, yet expressive Statically Typed via Type Inference Rich Constructs Functions as First Class Citizens Power of DSL Interoperability with the Java Ecosystem 

Typesafe Platform Scala Programming Language PlayFramework for Web Applications sbt for builds Akka Typesafe Activator Misc. Tools 

Typesafe Activator A very simple way to start with Scala and Play! Applications Browser-based Interactive Comes with a good number of templates 

Typesafe Activator 

Typesafe Activator Use if you do not have an IDE Use it to play with various templates it comes with Yet to mature but a (very) good start 

Play! Framework Simple Convention over Configuration Focus on Developer Productivity Asynchronous Processing Model Makes testing easy JSON support for RESTFul Applications 

Play! Framework Not a J2EE compatible framework Does not follow the traditional request/response model 

Creating a Play! Project 

Using an IDE 

Eclipse Import 

Gotchas! Start with a fresh installation of ScalaIDE Go to Install New Software – Select ScalaIDE – Check Play2 Plugin 

Run the App! 

And Play! with it http://localhost:9000 Test the app with play test 

Play! Core Concepts Uses sbt as the build system (In a special way to support always-on builds) 

Play! Core Concepts MVC Folder Structure Controllers Routes File Tests 

Play! Actions In simple terms, an Action takes function, that takes a request Request, and returns a Response. 

Play! Actions All routable methods of a Controller are Actions (Request => Result) function 

The almighty Action A simple, no-request that returns a result. A function that makes the Request available to the block You can pass a BodyParser to the Action as an argument Default BodyParsers are available for common content types 

Play! Console Demo run vs. ~run With ~ run or run, change the app with syntax error Fix the app and retry Use the app with ~ test in Play! Console Change the code and watch the tests fail Change the tests and watch them pass 

The Routes file Type-safe way to define mappings from URLs to Actions Rich support for basic data types Handling of defaults 

RESTFul APIs Not JSON over HTTP Not JSON representation of your Database No Spec or official standard 

RESTFul APIs Envision the entities as HTTP resources Envision the interactions as HTTP methods Read RFC 2616 

Play! Hands-on API Model – A Person APIs – Get all, Get by First/Last/Zip, Add a person JSON Request and Response 

Model object PersonModel { val persons = ArrayBuffer(Person("Manish", "Pandit", 94568), Person("John", "Doe", 95051), Person("My", "Neighbor", 94568)) def add(p: Person) = persons += p def getAll = persons def getByFirstName(first: String) = persons.filter(_.first == first) def getByLastName(last: String) = persons.filter(_.last == last) def getByZip(zip: Int) = persons.filter(_.zip == zip) } case class Person(first: String, last: String, zip: Int) 

Controller object SimpleAPI extends Controller { implicit val personWrites = Json.writes[Person] implicit val personReads = Json.reads[Person] def getAll = Action { Ok(Json.toJson(PersonModel.getAll)) } def add = Action(parse.json) { request => Logger.info(s"Body is $request.body") request.body.validate(personReads) match { case x: JsError => BadRequest case x: JsSuccess[Person] => PersonModel.add(x.get) Created } } def getByFirstName(first: String) = Action { val list = PersonModel.getByFirstName(first) if (list.isEmpty) NotFound else Ok(Json.toJson(PersonModel.getByFirstName(first))) } } 

Routes #  ~~~~   # Routes # This file defines all application routes (Higher priority routes first) # ~~~~ # Home page GET /persons controllers.SimpleAPI.getAll GET /persons/first/:first controllers.SimpleAPI.getByFirstName(first) GET /persons/last/:last controllers.SimpleAPI.getByLastName(last) GET /persons/zip/:zip controllers.SimpleAPI.getbyZip(zip:Int) GET /persons/default controllers.SimpleAPI.getByFirstName(first="Manish") POST /persons controllers.SimpleAPI.add 

Play! Packaging Use play dist to package the app as a zip file Run using the start script 

Play! Advanced Topics Reactive Programming Akka, Futures, Promises Play WS Library Anorm and Slick 

Further reading http://www.playframework.com/ http://typesafe.com/platform StackOverflow Source : https://github.com/lobster1234/SVCC2013 

We are hiring! netflix.github.io techblog.netflix.com jobs.netflix.com 

Fin Manish Pandit @lobster1234 mpandit@netflix.com linkedin.com/in/mpandit slideshare.net/lobster1234