GraphQL Introduction

GraphQL IntroductionSerge Huber, Jahia CTO

[email protected]

#graphqlMake some noise

1WHAT IS GRAPHQL ?

…and what it isn’t.

1 WHAT IS GRAPHQL ?I like opposites

It is not:• A query language like SQL, JCR-SQL,

etc…• A URL specification• A finalized standard• A standard submitted to a standards

body• A 100% JSON standard• A mature standard, changes are still

happening

1 WHAT IS GRAPHQL ?A (very) quick look

Courtesy of the GraphQL.org home page

1 WHAT IS GRAPHQL ?Some users

Courtesy of the GraphQL.org home page

See more on http://graphql.org/users

1 WHAT IS GRAPHQL ?A quick demo

https://www.graphqlhub.com

1 WHAT IS GRAPHQL ?Schemas• A schema that describes: • Objects• Object fields• Field arguments & directives• Interfaces• Unions

1 WHAT IS GRAPHQL ?Fields, the key to understanding GraphQL !A field may be:• a static value• a value resolved through

code

Field may have:• Arguments that are like

parameters to a method call• Constraints to filter data• Directives that make the field

conditional in the result

Don’t think of fields as variables, think of them as methods !

1 WHAT IS GRAPHQL ?Queries• Queries• Specify what fields are part of

the result• Only fields specified in the

schema are acceptable• Field may be the result of

computations• Fields may specify arguments

that will constrain the results (such as id:10)

• Directives may also be used (such as @include)

• Variables may be used• Fragments• Type casts !• Pagination (Relay schema)

1 WHAT IS GRAPHQL ?Mutations• Mutations• Make it possible to

write/modify data• Very similar syntax to

queries

1 WHAT IS GRAPHQL ?Compared to REST APIs

REST GraphQL

Specifies URL structure YES NO

Specifies request / response body structure NO YES

Validation NO YES

Requires a declared schema NO YES

Key-Value friendly YES NO

Extra (non CRUD) methods standardized NO YES

2GRAPHQL INTEGRATION

Mapping to existing stuff

2 GRAPHQL INTEGRATIONTypical architecture

Client

Server

React / React Native

Relay

GraphQL

Data & Services

2 GRAPHQL INTEGRATIONRelay

2 GRAPHQL INTEGRATIONAngular 2 and Relay

https://tech.small-improvements.com/2016/02/25/angular-2-and-relay/

2 GRAPHQL INTEGRATIONJava Libraries

• graphql-java : Java implementation of GraphQL

• graphql-java-servlet : A relay-compatible OSGI Java servlet

• graphql-java-annotations : Can generate GraphQL schemas from Pojo annotations !

3GRAPHQL TOOLINGWhat there’s tooling already ?

3 GRAPHQL TOOLINGGraphiQL

3 GRAPHQL TOOLINGGraphiQL

Features• Auto-completion based on GraphQL

schema• Execution of GraphQL queries and

mutations• Input of variables• Result viewer• Built-in documentation browser

3 GRAPHQL TOOLINGGraphQLHubA hub to test public GraphQL services such as :• Hacker News• Reddit• GitHub• Twitter• Giphy• Relay-compatible Key-

Value store

But (strangely) not Facebook (probably because of API keys)

3 GRAPHQL TOOLINGAwesome GraphQLBest list of tools & libraries at :

https://github.com/chentsulin/awesome-graphql

Some cool examples:

SQL Libraries• GraphpostgresQL - GraphQL for Postgres.• sql-to-graphql - Generate a GraphQL API based on your SQL

database structure.• PostGraphQL - A GraphQL schema created by reflection over a

PostgreSQL schema.

4DX INTEGRATION DEMO

You’re not serious are you ?

4 DX INTEGRATION DEMOThe sourceProject available here:

http://www.github.com/Jahia/graphql-core-feature

• Built as a Karaf features, requires DX 7.2 to run• Embeds GraphiQL as an administration UI !• Extensible through other modules, they simply provide query and

mutation providers !• Dynamic schema, re-generated every time a new mutation or query

provider is registered in the OSGi services registry• Based on the graphql-java-servlet project, available at:

http://www.github.com/graphql/graphql-java-servlet• Still a lot to do, just beginning• Code is clearly a proof of concept prototype, lots of things will need

cleaning up and refactoring• Mapping to JCR content still to be defined.

5 QUESTIONS AND ANSWERSAsk away, don’t be shy

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