Simplify Access to Data from Pivotal GemFire Using the GraphQL (G2QL) Extension

© Copyright 2017 Pivotal Software, Inc. All rights Reserved. Version 1.0
Sai Boorlagadda
October 17, 2018
Geode GraphQL Extension
(G2QL)

Agenda
● GraphQL Introduction
● Geode + GraphQL = G2QL
● Demo
● Next Steps

GraphQL Introduction
REST vs GraphQL

What’s GraphQL?
● new API standard by Facebook
● query language for APIs
● declarative way of fetching &
updating data

Strong Community
> 75 companies using GraphQL
https://graphql.org/users/

Example: Blogging App using REST

Overfetching and Underfetching

Product Centric APIs
backend APIs are storage-centric
frontend APIs are product-centric

GraphQL = Composition + Projections
Example: Blogging App using GraphQL

Core Concepts
Queries & Mutations

Queries
... only read data
query MessageQuery {
Message(id: “1”) {
text
sentBy {
name
}
}
}

Queries
... only read data
text
sentBy {
name
}
}
}
Operation Type
3 Operation Types:
- query (default)
- mutation
- subscription

Queries
... only read data
text
sentBy {
name
}
}
}
Operation Name

Queries
... only read data
text
sentBy {
name
}
}
}
Fields

Queries
... only read data
text
sentBy {
name
}
}
}
Root Field

Queries
... only read data
text
sentBy {
name
}
}
}
Selection Set

Queries
text
sentBy {
name
}
}
}
... only read data
{
“data”: {
“Message”: {
“text”: “Hello!”,
“sentBy”: {
“name”: “Bob”
}
}
}
}

Mutations
mutation CreateMessage {
createMessage(text:“Hi”) {
id
}
}
... write and read data
{
“data”: {
“createMessage”: {
“id”: “3”
}
}
}

Subscriptions
● event-based real-time updates
● clients subscribe to specific events
● usually implemented with websockets

GraphQL Server
Schema & Resolvers

GraphQL Server Components
● GraphQL Schema Definition
● Resolver Functions
● GraphQL execution layer
● Network layer

● Network layer } graphql libraries

● Network layer
} Developer
Responsibility

GraphQL Schema
● Strongly typed & written in Schema
Definition Language(SDL)
● defines API capabilities ( = contract for
client-server communication)
● root types: Query, Mutation, Subscription

Example: CRUD for user type
type User {
id: String!
name: String!
}
type Query {
user (id: String): User,
users (id: [String]): [User]
}
type Mutation {
createUser (key: String!, user: User!): User,
updateUser (key: String!, user: User!): User,
deleteUser (key: String!): User
}
query {
user (id: “1“) {
name
}
}
{
“user”: {
“name”: “Bob”
}
}
1.Schema 2.Query 3.Response

GraphQL Resolvers
@Component
public class UserDataFetcher implements DataFetcher<User> {
@Autowired
private final UserDao userDao;
@Override
public User get(DataFetchingEnvironment env) {
String userId = env.getArgument(“userId”);
return userDao.find(userId);
}
}

● Schema Duplication
● Boilerplate Overdose
● Client/Server Data Mismatch
● Superfluous Database Calls
first impressions

Schema Duplication
Solution: GraphQL Schema Generation
GraphQL Schema Database Schema

Boilerplate Overdose
● Define GraphQL Schema
● Write Resolvers for CRUD
Solution: Convert queries and mutation to Geode Operations and OQL

Client/Server data mismatch
Solution: Translate GraphQL to OQL
Post:
{
“id”: “1”,
“title”: “G2QL”,
. . .
. . .
“user”: {
“id”: “1”,
“name: “Sai”,
. . .
. . .
}
}
id userid title contents
1 1 G2QL G2QL is a ...
/Post

Problem: Schema Duplication
Solution: GraphQL Schema Generation
Problem: Boilerplate Overdose
Solution: Auto convert queries and mutation
to Geode Operations and OQL
Problem: Client/Server data mismatch
Solution: Convert GraphQL to OQL
Problem: Superfluous Database Calls
Solution: Batching & Caching
G2QL is the answer

Geode GraphQL Extension
● Turns your cache into GraphQL API server
● Introspects and defines GraphQL schema
- types, queries, mutations
● Converts queries & mutations to Region
Operations and OQL
- no need to write resolvers

G2QL introspects your cache
type Customer {
fields: - from ValueConstraint
}
type Query {
customer(key: String): Customer,
customer(firstName: String): Customer
}
type Mutation {
createCustomer(key: String!, customer: customer!): Customer,
updateCustomer(key: String!, customer: Customer!): Customer,
deleteCustomer(key: String!): Customer
}
Regions
Customer<String, Customer>
Order<String, Order>
Indexes
create index --name=FirstNameIdx
--expression=firstName --
region=/Customer
Cache Configuration GraphQL Schema
Value Constraints == Types

type Customer {
}
type Query {
}
type Mutation {
}
Regions
Indexes
region=/Customer
Queries with Key & Indexes

type Customer {
}
type Query {
}
type Mutation {
}
Regions
Indexes
region=/Customer
Mutations with Region operations

@GeodeGraphQLDescription
@GeodeGraphqDescription(“A student is a Student”)
Class Student{
String id;
String name;
}

@GeodeGraphQLIgnore
@GeodeGraphqlIgnore
Class Student{
String id;
String name;
}

@GeodeGraphQLConnection
Class Person{
String id;
String name;
@GeodeGraphqlConnection(region=”/person”)
List<String> friends; //store keys to person objects
}

GraphQL clients
There are close to 100 libraries in >20 languages
https://github.com/chentsulin/awesome-graphql

Next Steps…
● Non-scalar keys
● Introspect PDX types
● Introspect Lucene indexes
● Introspect Functions
● Cache listeners
● Security
● GraphQL subscription
● GraphQL schema -> cache configuration

References
● G2QL - https://github.com/sboorlagadda/g2ql
● GraphQL - https://graphql.org/
● Apollo GraphQL - https://www.apollographql.com/
● graphql-java - https://github.com/graphql-java/
○ Provides query parser, type system, schema parser, hooks to resolvers

Simplify Access to Data from Pivotal GemFire Using the GraphQL (G2QL) Extension

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