REST-ish APIs have become the de-facto standard in the last 10 years. But is it always the right choice? Facebook, GitHub, and Pinterest challenge status quo in network communication and embrace GraphQL - query language for the APIs. This evolving standard also gives you runtime to execute the queries and enables comprehensive dev tooling, making it juicy for a developer to try and explore. That's what we, at Wix, did too! In this talk, we will see GraphQL in real, practical action under Java sauce. We'll elaborate on our experience with GraphQL at Wix, see how it compares to REST, and, like with every other technology, understand its limits and shortcomings. So, is GraphQL right for you?

1. APIs The New Way
Volodymyr Tsukur

2. API,
Volodymyr Tsukur
not DB!

3. Volodymyr Tsukur
Lead Engineer,
Guild Master @
Partner @
EASYHUNT
Program Committee @
JEEConf, XP Days
flushdia vtsukur

4. Lithuania
Ukraine
Kyiv
Dnipro
Vilnius
Локации Wix Engineering
Israel
Tel Aviv
Be’er Sheva
~ 110M+ users*
~ 700 engineers
~ 1800 employees
~ 500 microservices

7. title
price
images
description
info
...
{
}
GET /products/:id

8. imagesimages(1)
priceprice
titletitle
[
]
description
GET /products
...
info
{
}

9. 10%!

10. OVER-fetching
01

11. GET /carts/:id
items [
{
product
quantity
total
}
{
}
]
subTotal

12. GET /carts/1
GET /products/59eb838e3f
GET /products/59eb88c400
GET /products/59eb838e40

13. - UNDER-fetching
- extra requests
02

14. GET /carts/1?projection=with-products
...

15. GET /carts/1?projection=summary
GET /carts/1?projection=
GET /carts/1?projection=
GET /carts/1?projection=with-products

16. - no unified & widely adopted
standard :( *
- harder to collaborate :(
03

18. How to @deprecate and
phase out outdated stuff?
04

20. 2012

23. 2015

24. “... is a query language for APIs and a runtime for
fulfilling those queries with your existing data”

25. type User {
name: String
friends: [User]
city: City
}
type City {
name: String
population: Int
citizens: [User]
}
1. Define schema
{
user(name: String): User
...
}

26. 2. Ask for data
user(name: String): User

27. 2. Ask for data
{
user(name: “Vanya Unicorn”) {
friends {
name
}
city {
name
population
}
}
}

28. 3. Get it!
{
user(name: “Vanya Unicorn”) {
friends {
name
}
city {
name
population
}
}
}
{
“data”: {
“user”: {
“friends”: [
{ “name”: “Lena” },
{ “name”: “Stas” }
]
“city”: {
“name”: “Kyiv”,
“population”: 2928087
}
}
}
}

29. only necessary data
{
“data”: {
“user”: {
“friends”: [
{ “name”: “Lena” },
{ “name”: “Stas” }
]
“city”: {
“name”: “Kyiv”,
“population”: 2928087
}
}
}
}
{
user(name: “Vanya Unicorn”) {
friends {
name
}
city {
name
population
}
}
}

30. in one request *
{
“data”: {
“user”: {
“friends”: [
{ “name”: “Lena” },
{ “name”: “Stas” }
]
“city”: {
“name”: “Kyiv”,
“population”: 2928087
}
}
}
}
{
user(name: “Vanya Unicorn”) {
friends {
name
}
city {
name
population
}
}
}
HTTP POST

31. let us see how it works!

32. WYSIWYG
efficient fetching
easier to develop
analytics
any data source and transport

34. graphql-java

35. HTTP
Cart Service
Product Service

36. let us rock and roll!

38. running query

39. {
cart(id: 1) {
items {
product {
title
price
images(limit: 1)
sku
}
quantity
total
}
subTotal
}
}
1)

40. {
cart(id: 1) {
items {
product {
title
price
images(limit: 1)
sku
}
quantity
total
}
subTotal
}
}
2) SELECT ... FROM Cart
INNER JOIN Item ...

41. {
cart(id: 1) {
items {
product {
title
price
images(limit: 1)
sku
}
quantity
total
}
subTotal
}
}
3)
+ n x
product {
title
price
images(limit: 1)
sku
}
product {
title
price
images(limit: 1)
sku
}
GET /products/1
GET /products/2
GET /products/3

43. e x p e c t a t i o n s

44. R
e
a
l
i
t
y

45. {
cart(id: 1) {
items {
product {
title
price
images(limit: 1)
sku
}
quantity
total
}
subTotal
}
}
+
GET /products?ids=1,2,3
@Batched

46. let’s fix it!

47. Security

48. {
user(name: “Vanya Unicorn”) {
friends {
name
friends {
name
friends {
name
friends {
name
...
}
}
}
}
}
}

51. limit query depth
limit query complexity

52. let us defend!

53. throttling / rate limiting
set timeouts
pagination

54. schema {
query: Query
}

55. schema {
query: Query,
mutation: Mutation
}

56. type Mutation {
addProductToCart(cart: ID!,
product: ID!,
count: Int = 1): Cart
}

57. let us mutate!

58. +
+

60. I want it !!!

61. but let us see the BAD parts

62. caching
security
error handling
arbitrary resources / file uploads

63. operation idempotency?
operation naming
hypermedia
Java ecosystem

65. Alternatives
https://philsturgeon.uk/api/2017/01/24/graphql-vs-rest-overview/
https://blog.runscope.com/posts/you-might-not-need-graphql

66. NO !!!

67. but it shines
as an
integrated
solution

68. schema {
query: Query,
mutation: Mutation,
subscription: Subscription
}

69. type Subscription {
productAdded(cart: ID!): Cart
}

70. subscription {
productAdded(cart: 123) {
items {
product ...
}
subTotal
}
}
{
“data”: {
“productAdded”: {
“items”: [
{ “product”: ... },
{ “product”: ... },
{ “product”: ... },
{ “product”: ... }
]
“subTotal”: 289.33
}
}
}
://

71. {
“data”: {
“productAdded”: {
“items”: [
{ “product”: ... },
{ “product”: ... },
{ “product”: ... },
{ “product”: ... }
]
“subTotal”: 289.33
}
}
}
subscription {
productAdded(cart: 123) {
items {
product ...
}
subTotal
}
}
://

74. https://github.com/vtsukur/graphql-java-store
sample, not
production
ready code!

76. Questions?
volodymyrt@wix.com
flushdia vtsukur