Hi. I’m Karan.

• CS, UW
• <3 code
• goel.im
• @TheKaranGoel (follow me)

Sudo Soldiers

• https://www.facebook.com/groups/uwhackers/
• https://github.com/SudoSoldiers/
• http://students.washington.edu/uwsudo/
• uwsudo@uw.edu

Weekly demos

• 2 pitches every week
• Complete/incomplete projects + ideas welcome
• Talk about: Motivation, challenged, help, experience
• 2 minutes each pitch - hard limit
• Sign up now!

Today's Demos

• scInstant - Karan Goel
• UW Open Data - Rukmal Weerawarana

API

• defines interaction between components
• software or hardware
• HTTP - REST, SOAP

REST

• Representational state transfer
• Web standard
• Anything can make a request and process the response
• Dissertation by Roy Thomas Fielding

Why bother

• API's break strong ties between components
• Separation of client from server
• 1 API - Multiple devices
• Easier to make clients
• Expansion - Motivate other developers to leverage your platform

JSON

• Data exchange format
• JavaScript Object Notation
• name: value pairs

{
    "firstName": "John",
    "lastName": "Smith",
    "isAlive": true,
    "age": 25,
    "height_cm": 167.64,
    "address": {
        "streetAddress": "21 2nd Street",
        "city": "New York",
        "state": "NY",
        "postalCode": "10021-3100"
    },
    "phoneNumbers": [
        { "type": "home", "number": "212 555-1234" },
        { "type": "fax",  "number": "646 555-4567" }
    ]
}

HTTP methods

REST is all about simplifying API's. It defines 4 methods (verbs):

• GET - Read a specific resource
• PUT - Update a specific resource
• DELETE - Remove/delete a specific resource
• POST - Create a new resource.

Create – GET: /user/new?name=John
Read – GET: /user/1
Update – GET: /user/1/update?name=Doe
Delete – GET: /user/1/delete

Create – POST: /user (with request body)
Read – GET: /user/1
Update – PUT: /user/1 (with request body)
Delete – DELETE: /user/1

Resource vs Representation

Resource

Consider http:/test.com/user/1. Here, user/1 is a resource.

Representation

Set of attributes related to the resource returned by the URI. A `GET http:/test.com/user/1` returns the representation of a user as:

name: John
Age: 21

80/20

• Making an API is 80% art and 20% science.
• Art - Creating a sensible URL hierarchy
• Science - Creating sensible resource names
• Follow the standards

• URL hierarchy should make it obvious - how to use the API
• Resource names should provide context for service request

GET /events - get all events
GET /events/concerts - get all concerts
GET /events/concerts/123 - get a specific concert

• URL's are hierarchical - leverage that
• Design for clients, not the data
• Avoid verbs, use nouns
• Keep URL's short and sensible

HTTP Response Codes

• 200 OK
• 201 CREATED
• 400 BAD REQUEST
• 401 UNAUTHORIZED
• 404 NOT FOUND
• 500 INTERNAL SERVER ERROR
• 418 - I'M A TEAPOT

Headers

Client to Server

• Authorization - Enable auth for any method
• User-Agent - Info about the client
• Host - Domain of the client

Server to Client

• Content-Encoding - Compression being used
• Content-Length - Size of response in bytes

State

REST is Stateless

That means...

• Do not create session
• Client must pass authorization in every call
• Never, never use a session key

Let's make an API

Acronyms API

We have the data and starter code. Let's hack something!

Use Postman to test the API.

Deploying

Heroku

• PAAS
• Free
• Easy deployment
• git push heroku master
• Addons for pretty much anything you want

Deploy our API

# make a Procfile
$ echo "web: node app.js" > Procfile

# test using foreman
$ foreman start

# (git add, git commit your code)

# create an app
$ heroku create [app name]

# to the moon
git push heroku master

Detailed tutorial