RPC, REST, and now GraphQL? Yes! Facebook’s latest standard is shaking up the API world as it promises to provide consumers with more power and flexibility than they’ve had with previous standards. Sounds great, but how should one get started surfacing up data from their relational databases with GraphQL? In this session, attendees will get a brief overview of GraphQL APIs and learn about some of the key advantages they can offer over REST APIs. Next, a technical deep dive will show how GraphQL works and how it can be tied into new or existing relational data stores.

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Intro to GraphQL for Database Developers
Dan McGhan
Developer Advocate @Oracle
May 16, 2019

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Safe Harbor Statement
The following is intended to outline our general product direction. It is intended for
information purposes only, and may not be incorporated into any contract. It is not a
commitment to deliver any material, code, or functionality, and should not be relied upon
in making purchasing decisions. The development, release, timing, and pricing of any
features or functionality described for Oracle’s products may change and remains at the
sole discretion of Oracle Corporation.

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About me
• Dan McGhan
– Developer Advocate @Oracle
– Focus on JavaScript and Oracle Database
• Contact Info
– dan.mcghan@oracle.com
– @dmcghan
– jsao.io
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Agenda
Overview of GraphQL
Type system and query language
Demo
1
2
3
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Agenda
Overview of GraphQL
Type system and query language
Demo
1
2
3
6

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What is GraphQL?
• A query language for APIs created by Facebook
– Designed to make APIs more flexible and efficient
• Consists of
– Type system
– Query language and execution semantics
– Static validation
– Type introspection

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GraphQL history
• Internal Facebook project since 2012
• First specification released publicly in 2015
– Regular updates since then
• 2019: One of the hottest buzzwords in tech
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Spec vs. implementation
• Facebook publishes a spec and a reference implementation
– The spec describes how a GraphQL implementation should work
– GraphQL.js is the reference implementation in JavaScript

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Primary benefits of GraphQL
• Addresses under fetching
– Can get many resources in a single request
• Addresses over fetching
– Can project only what’s needed for the app
• Organization is based on types and fields rather than URL endpoints
– GraphQL servers have a single “smart” endpoint
• Evolve APIs without versions

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REST vs GraphQL
REST GraphQL
Can send over HTTP Can send over HTTP
Can return JSON Can return JSON
Endpoint is the object identity Object identity is part of the query
Resource is determined by the server Server declares what is available, client
requests what it needs
May require loading from multiple URLs Gets all the data in a single request
GET or POST to same URL query{} and mutation{} use same URL
Calls are stateless Query and mutation operations are
stateless
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Web Browser Web Server Database
SQL

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Web Browser Web Server Database
SQLGraphQL

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Agenda
Overview of GraphQL
Type system and query language
Demo
1
2
3
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Type system
• Describes the objects that can be returned
– Schema Definition Language expresses the GraphQL schema shape and types
• Default scalar types
– ID, Int, Float, String, Boolean
• Other types
– Object, Interface, Union, Enum, Input Object, List, Directive

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Operation types
• Query
– Think: SELECT or Data Query Language (DQL)
• Mutation
– Think: Data Manipulation Language (DMLP
• Subscription
– Think: Continuous Query Notification (CQN)

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Let’s start with something we know…

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EMP and DEPT DDL

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EMP and DEPT as GraphQL schema language

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Adding a root object

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Rolling the query root into a schema

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REST request/response
REST GET
/departments/1
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REST Response
{
"deptno": 1,
"dname": "ACCOUNTING",
"loc": "NEW YORK"
}

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GraphQL query/response
GraphQL Query
{
department(id: 1) {
deptno
dname
loc
}
}
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Response
{
"data": {
"department": {
"deptno": 1,
"dname": "ACCOUNTING",
"loc": "NEW YORK"
}
}
}

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GraphQL query/response
GraphQL Query 2
{
department(id: 1) {
deptno
dname
}
}
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Response 2
{
"data": {
"department": {
"deptno": 1,
"dname": "ACCOUNTING" }
}
}

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Agenda
Overview of GraphQL
Type system and query language
Demo
1
2
3
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GraphQL Demo Technologies
‘GraphiQL’ UI express, express-graphql,
graphql, and node-oracledb
modules
Oracle Database
Queries and responses GraphQL requests over HTTP Persistence

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Closing thoughts
• REST isn’t going away anytime soon
– And it still has some advantages over GraphQL
• But GraphQL is like giving SQL to front-end developers
– We all know how powerful SQL is!
• Keep GraphQL on your radar
– Front-end devs will likely be asking for it soon…

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Where to go from here
• https://graphql.org/
– The “home” for GraphQL; great learning material
• https://www.howtographql.com
– Another excellent learning resource with videos
• https://graphql.github.io/graphql-spec/
– Specification
• https://goodapi.co/blog/rest-vs-graphql
– Fair, unbiased comparison of REST and GraphQL