Zero to API Hero

Consuming 3rd party APIs like a pro

Cecy Correa, @cecycorrea

#RailsConf 2016

Who? Why?

My name is Cecy Correa

Associate Engineer at ReturnPath

The problem

Too much magic?

Rails.application.routes.draw do
  resources :users
end
					

$ rake routes
   Prefix Verb   URI Pattern               Controller#Action
    users GET    /users(.:format)          users#index
          POST   /users(.:format)          users#create
 new_user GET    /users/new(.:format)      users#new
edit_user GET    /users/:id/edit(.:format) users#edit
     user GET    /users/:id(.:format)      users#show
          PATCH  /users/:id(.:format)      users#update
          PUT    /users/:id(.:format)      users#update
          DELETE /users/:id(.:format)      users#destroy
					

Credit: @schneems

Agenda

Tools you can use to consume APIs good (and do other things good too)

• Anatomy of an API call
• HTTP status codes (and what to do about them!)
• Working with gems
• Tools, debugging, testing
• Demo time!

Anatomy of an API call

Anatomy of an API call

Assumptions

• Using HTTP protocol
• RESTful API
• Using JSON

Not all APIs are this way, but most you will encounter for public consumption are.

HTTP status codes! and what to do about them

Status codes

Status codes are not arbitrary!

Status codes have been established, agreed upon (RFC 7231)

Some people spend a lot of time picking the right status code!

(I'm going to focus on the ones used for APIs most often)

Status codes in a nutshell

• 10x: informational
• 20x: everything is a-ok 👍
• 30x: go away (redirects)
• 40x: YOU messed up
• 50x: WE messed up

200

201: created

202

302

400: Your request is bad and you should feel bad

You should not submit the request again without modifications (i.e. check your params, bro)

401: Unauthorized

Check your creds, bro

403: Forbidden

Creds could be wrong, but also not

404

418: I'm a teapot

April Fools' Joke

Found in the wild?

429: API limit reached

500

Standard error. Not sure what happened but def. not your fault.

503: Unavailable

API could be down, or maybe throttling

For real,pay attention to the status code you get!

No one expects you to memorize them, you can look them up.

Authentication

• No authentication
• Developer authentication
• User authentication

No authentication

Some APIs don't require authentication

• OMDB
• Open Weather Map
• Data.gov

Developer authentication

Some APIs require authentication in the form of an API key and secret.

How you authenticate via API key and secret depends on the API:

• As part of the URL
• In the Headers

Check your API docs for information on how to authenticate.

DEMO

Let's make some test calls!

• API that requires no authentication
• API that requires some authentication

We'll use cURL for this!

We just used cURL to make API calls!Anyone can do this!

No excuse for not making test calls before you start integrating the API.

User authentication

In some cases, users may need to grant you permission to access their data or perform actions on their behalf.

• OAuth 1.0 and 2.0
• OAuth dance can be complicated, but lots of libraries available!
• Some APIs facilitate this process.

Authentication vs. Authorization

Authentication: prove you are who you say you are

Authorization: what you are authorized to access (aka scope)

Demo

Let's make an Oauth request and see how it works!

Tools for productivity!

Postman

Postman

Crazy useful functionality for working with APIs!

• Make API calls
• Save API calls
• Create environments to reuse
• Save "runs"
• Download sample "code"

Demo: Let's make an Oauth 1.0 call with Postman

Gems

Official API wrappers / libraries

• Look for official libraries
• Lots of maintainers
• Recently updated
• Good documentation

What if there are no libraries available?

Or if you don't like the library that is available?

Develop against the REST API!

It's easy!

You know the basics!

You know the components of a call

If you've made test calls, you know what to expect

HTTP client

• HTTParty
• Faraday
• HTTP: The Gem!
• Net::HTTP

Great presentation by Hiroshi Nakamura comparing HTTP clients

All HTTP clients are not created equal

3 "pure Ruby" libraries

• Net::HTTP
• Excon
• httpclient

Also patron, which uses libcurl

Other Ruby libraries are wrappers of these ^^

All HTTP clients are not created equal

• HTTParty: wrapper for Net::HTTP
• Faraday: select between Net::HTTP, Excon, or patron
• HTTP: The Gem! is "Native implementation of HTTP"

You're going to want to do some research into what you may need / want.

Demo: Using HTTParty to create your own wrapper

INCEPTION

Caution!

Never commit your API key / secret to source control!

Use environment variables!

Testing & Debugging

Testing

How do you test a 3rd party API you are consuming?

• Should you test to see if the API is down?
• Should you test against the live API?
• Should you test your integration of the API?

Testing

How do you test a 3rd party API you are consuming?

• Should you test to see if the API is down?
• Should you test against the live API?
• Should you test your integration of the API? YES!

Need to know if API is down?

Check the API status page!

Most APIs have it.

Subscribe to it, feed it into Slack.

#REALTALK

Why not test against the live API?

Don't test against a live API.

Don't test against a live API.

Don't test against a live API.

Testing your integration: best practices

• Mock / stubb API responses
• Test how you handle the responses, errors
• Clean up after yourself!

Testing your integration: mocking responses

VCR: gem that "records" API responses

Run your tests against it so you don't hit the live API

There's even versions of VCR in other languages!

Trust & Communication are key

Debugging & webhooks

Debugging

• Request Bin
• Runscope
• Mockbin

Request Bin

Runscope

Mockbin

Live Demo!

Let's set up a webhook and test it.

Tweet anything to @cecycorrea to see it in action!

Resources

Slides: github.com/cecyc/zero-to-api-hero

• Super basic primer on APIs by Zapier
• Great collection of public APIs!
• HTTP client survey by Avdi Grimm
• What's up with Ruby libraries, Julia Evans
• HTTP client comparison
• Deploy your own Request Bin on Heroku

Thank you!