This document is a quick introduction to GraphQL, a query language for APIs that allows clients to request specific fields, enabling more efficient data retrieval compared to REST. It outlines GraphQL's advantages, architecture, and essential concepts such as types, schema, queries, and mutations, along with practical implementation examples. Additionally, it provides links to demo code and invites feedback from readers.

1. A QUICK INTRODUCTION TO GRAPHQL
ASHOKKUMAR T.A. | 25-MAR-20201

2. WHAT IS GRAPHQL
 A query language for APIs
 Created at Facebook in 2012 & open sourced in 2015
 Specification, many implementations in multiple languages
 Specs at http://spec.graphql.org/
 GraphQL Foundation – neutral body to promote widespread adoption

3. WHY GRAPHQL
 Less chatty
 Client chooses the fields it needs, tailor made response
 API evolution without versioning
 Rapid development
 Best for microservices – combine multiple APIs, pick only the needed fields

4. GRAPHQL VS. REST
Response
Specific vs. Standard
Architecture
Client Driven vs. Resource oriented
URLs
Single POST URL vs Resource based
Language
Query/Mutation vs. GET/POST/PUT/DELETE
Eco-system
Fast growing vs. Well estabilished

5. UNDERSTANDING GRAPHQL ARCHITECTURE

6. BASIC BUILDING BLOCKS
 Types
 Schema
 Queries
 Mutations
 Resolvers
 Client

7. GETTING STARTED – WELCOME & GREET API’S
 App with 2 APIs – welcome & greet
 GraphQL.js
 With Express GraphQL Server
 Query APIs – welcome & greet
 Implementing the resolvers
 Putting it all together
 GraphiQL Client

8. DEMO
 Multiple API calls in one request, response controlled from client
 OOB parameter validations, API documentation
 Demo code can be downloaded from https://github.com/ashokkumarta/graphql-samples/tree/main/01

9. DIGGING IN FURTHER
 Mock the training schedule
 Types
 Student
 Course
 Training
 Schema definition is the key

10. DEMO
 User defined types & conditions
 Selection of attributes needed in the response dictated by client
 Demo code can be downloaded from https://github.com/ashokkumarta/graphql-samples/tree/main/02

11. DISCUSSION

12. THANKYOU
Feedback and suggestions welcome.
Please write to ashokkumar.ta@gmail.com