Phil Sturgeon - A No-Nonsense GraphQL and REST Comparison

Published on Thursday, March 15, 2018

Notes from Phil Sturgeon’s code talk at Flatiron School, 3/15/2018.

Slides available at philsturgeon.uk/speaking.

What is GraphQL?

GraphQL = FQL + (REST - Hypermedia)

A little FQLish, a little RESTish.

What is REST?

  • REST != CRUD API
  • REST == state machines over HTTP
  • Nice wrapper for models (keep logic in controller)
  • State machines can power Hypermedia controls (see below)

What is Hypermedia?

  • State machines over JSON
  • Misused
  • Misunderstood
  • Hypermedia links are not just for related data

More on HATEOS:

Level 1: string containing URL

  • no guarantee of success
  • make url respond to options

Level 2: add metadata to options payload

  • use JSON schema to detail fields
  • use JSON Hyperschema to detail potential actions
  • plus another optional layer of strictness
  • might to ignored/unnoticed by clients

Level 3: Add Hypermedia controls in response

  • Siren / HAL
  • Just send back everything (but end up with potentially huge response size)

Other protocols

  • SPARQL (2008) - not popular
  • FIQL (2008) - flexible, but not popular

Some things GraphQL is bad at

  • Caching
    • Query langagues are bad at caching
    • Each client has to guess rules for when and how to invalidate
    • Guessing rules for caching + how to invalidate, not ideal
    • REST says caching should be the server’s concern
    • Alternatives:
      • Endpoint-based APIs can utilize HTTP caching
        • super powerful
      • Network caching:
        • Varnish - sits in front of application server, all requests go through it
        • nginx
  • GraphQL is only as performant/efficient as the database you’re querying
    • Data has to be readily accessible for any query
    • Forces you to optimize database architecture
    • GraphQL is only efficient/performant as the database it’s querying
    • Watch out for the MEGA-INCLUDES problem (if people can ask for everything, they will)

Unlike HATEOAS, GraphQL can’t help you communicate with other systems (can’t do cross-API requests)

Some things GraphQL is good at

  • Customizable APIs
  • Can be more performant that REST (if used wisely)
  • Middleware: faraday-http-cache to magically respect cache headers
  • Can use fields, partials
    • But be aware: these custom queries completely ruin HTTP network caching tools
  • Handy when bulding JSONish / RESTish APIs

  • Makes deprecations easier
    • Easy to know who is requesting what fields (can infer from request logs).
    • Deprecate entire endpoing using sunset protocol (see faraday-sunset)

Before switching, questions to ask yourself:

  • How different are your clients from one another?
  • Do you never want to use HATEOS? (hard to switch back)
  • Do you need to support file uploads?

Small Wins

  • JSON Hyperschema is a good place to start before committing entirely.
  • nginx now supports HTTP2. Allows multiplexing requests.
  • Add cache control middleware.

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