My talk at Silicon Valley Code Camp 2013. Two years ago I gave a talk on PlayFramework with Java at SVCC. As with everything, PlayFramework has evolved into a far mature ecosystem with native Scala support, and Typesafe backing. PlayFramework 2 is a simple, MVC-based, convention over configuration web application framework for Java and Scala. It is rapidly gaining popularity as more and more companies are adopting it for building scalable, performant, share-nothing architectures. In this talk I'll cover the fundamentals of Play! Framework2, a brief overview of Scala, and demonstrate building a simple, RESTful API. This will be a very interactive, and hands-on session. It'd be awesome if you have played around with Scala, but if you have not, the scope of this talk does not require you to be a Scala expert. It will however be very useful if you've worked with other Web Application Frameworks like Jersey, CXF, etc. so you can cross-relate the concepts.

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

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

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

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

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

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

7. Typesafe Activator

8. 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

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

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

11. Creating a Play! Project

12. Using an IDE

13. Eclipse Import

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

15. Run the App!

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

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

18. Play! Core Concepts
MVC
Folder Structure
Controllers
Routes File
Tests

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

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

21. 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

22. 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

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

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

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

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

27. 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)

28. 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)))
}
}

29. 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

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

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

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

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

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