- Deepak Shevani works at Microsoft for the Azure group and recently became interested in GraphQL. - GraphQL was created by Facebook in 2015 to improve client-server communication when rebuilding their native mobile apps. It defines a query language and provides a server-side runtime to fetch the desired data. - GraphQL allows clients to get precisely the data they need through queries, reducing over- and under-fetching of data compared to REST APIs.

1. Graph QL
By - Deepak Shevani

2. Hello !!
I am Deepak Shevani
- Work at Microsoft for Azure group
- Recently got interested in GraphQL
- Contact : shevanideepak@gmail.com

3. Recognize this ?
3

4. History of Web Services
4
1960 1990 2000 2018
RPC SOAP REST GRAPHQL

5. REST Drawbacks
▧ Client Options : Http Verbs (GET, PUT, POST)
▧ Resources : /users /users/1 /users/1/posts
▧ No control over which fields to select
▧ Versioning of APIs is painful
▧ Overfetching / Underfetching
▧ Managing multiple endpoints is headache
▧ Change Process hindering agility
5

6. GraphQL origins ?
▧ In 2012, FB decided to rebuild native apps
▧ FB then used RESTful services & FQL
▧ Idea : Improving client server communication
▧ Result : In 2015, open sourced GraphQL
▧ Also provided reference implementation (js)
6

7. 1.
What is GraphQL ?
Will it kill REST ?
7

8. 1000 foot view
8
Query Data
Communication Medium

9. 1000 foot view
9
Query Data

10. 10
graphql.org

11. Meet GraphQL
QUERY LANGUAGE
GraphQL defines query language and
query is validated against type system
which is blueprint for API Data
SERVER SIDE RUNTIME
GraphQL provides server side runtime to
parse and route queries to fetch desired
data for the caller
More info about GraphQL can be found at
http://graphql.org/learn
11
STRONGLY TYPED
GraphQL allows you to do domain first
design that generates types and schema
CLIENT CENTRIC
GraphQL has developer centric view biased
towards clients

12. Meet GraphQL
QUERY LANGUAGE
GraphQL defines query language and
query is validated against type system
which is blueprint for API Data
SERVER SIDE RUNTIME
GraphQL provides server side runtime to
parse and route queries to fetch desired
data for the caller
More info about GraphQL can be found at
http://graphql.org/learn
12
STRONGLY TYPED
GraphQL allows you to do domain first
design that generates types and schema
CLIENT CENTRIC
GraphQL has developer centric view biased
towards clients

13. What is GraphQL
QUERY LANGUAGE
GraphQL defines query language and
query is validated against type system
which is blueprint for API Data
SERVER SIDE RUNTIME
GraphQL provides server side runtime to
parse and route queries to fetch desired
data for the caller
More info about GraphQL can be found at
http://graphql.org/learn
13
STRONGLY TYPED
GraphQL allows you to do domain first
design that generates types and schema
CLIENT CENTRIC
GraphQL has developer centric view biased
towards clients

14. Transport Agnostic
14

15. Example GraphQL Query
15
{
employee (id: 35) {
firstName
lastName
email
}
Resource Identifier
Required Fields

16. Example GraphQL Query
16
{
employee (id: 35) {
firstName
lastName
email
}
Resource Identifier
Required Fields
Id FirstName LastName Email DOB Salary Manager YOE
35 Deepak Shevani --- --- --- --- ---
36 Amit Sharma --- --- --- --- ---

17. Example GraphQL Query
17
{
employee (id: 35) {
firstName
lastName
email
}
Resource Identifier
Required Fields
Id FirstName LastName Email DOB Salary Manager YOE
35 Deepak Shevani --- --- --- --- ---
36 Amit Sharma --- --- --- --- ---
GET /api/employees/35

18. Example GraphQL Query
18
{
employee (id: 35) {
firstName
lastName
email
}
{
"employee" : {
"firstName" : "Deepak",
"lastName" : "Shevani",
"email" : "abc@y.com"
}

19. Example GraphQL Query
19
{
employee (id: 35) {
firstName
lastName
email
}
Nothing more, nothing less !!
Resolvers tells query where to go

20. “
20
REST GraphQLvs

21. What is GraphQL
QUERY LANGUAGE
GraphQL defines query language and
query is validated against type system
which is blueprint for API Data
SERVER SIDE RUNTIME
GraphQL provides server side runtime to
parse and route queries to fetch desired
data for the caller
More info about GraphQL can be found at
http://graphql.org/learn
21
Queries
Mutations
Subscriptions Fragments
Type System
Validation
Execution

22. GraphQL
Queries
22

23. Queries
Fetch data
Describes what data you want to fetch
from server. Response from server reflects
what you ask in query (selection sets). We
can create fragments to create reusable
selection sets
Query is GraphQL root type, as it maps to
an operation
Each field in selection set can have scalar
or object type.
Example
fragment basicInfo on Employee {
name
email
}
query {
employee (id : 35) {
... basicInfo
}
}
More info about GraphQL can be found at
http://graphql.org/learn
23

24. GraphQL
Mutations
24

25. GraphQL Operations
25
query GetTweets {
allTweets {
text
user
}
}
mutation Post ($body : String!) {
addTweet (body : $body) {
id
}
}
Query Operation
Mutation Operation
variables : { body : "LSPE 15th" }
variables : { body : "Loving it" }

26. Mutations
Update or Delete data
Like queries, we could name them. We
could also include selection sets to define
return types
Mutations are also root types, and they
usually include variables
Example
mutation createSong($title:String! $one:Int) {
addSong(title:$title, numberOne:$one) {
id
title
numberOne
}
}
More info about GraphQL can be found at
http://graphql.org/learn
26

27. GraphQL
Subscriptions
27

28. Subscriptions
Real time updates
Using web sockets, you could listen to real
time updates from the server
At Facebook, the use case was to fetch real
time likes on a page without getting
refreshed
Subscriptions are also root types
Example
subscription {
liftStatusChange {
name
capacity
status
}
}
More info about GraphQL can be found at
http://graphql.org/learn
28

29. Query Language
QUERY
query {
programs {
name
status
}
}
FRAGMENTS
fragment liftInfo on Lift {
name
status
capacity
night
elevationGain
}
29
MUTATIONS
mutation {
create(id: "program" status: OPEN) {
name
status
}
}
SUBSCRIPTIONS
subscription {
liftStatusChange {
name
capacity
status
}
}

30. Pros ?
30

31. Benefits
No Overfetching
.
No Underfetching Use queries
.
Easy deprecation Single Endpoint No custom endpoints

32. Cons
32

33. Cons
Learning Curve
.
Setup Required No Http Caching
.

34. Thanks!
Any questions?
You can find me at:
@deepak_shevani
shevanideepak@gmail.com
34