building apis in scala with playframework2

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