GraphQL is designed to describe APIs for an application. OpO lets an API be defined with GraphQL that describes a way to retrieve stored data. SDL files are loaded as part of the server configuration which describe the functions that are made visible to clients.

A GraphQL API is composed of three area, query, mutation, and subscriptions. Queries can view data which mutations are used to insert, update and delete data. More details on each category are provided by follwing the API map below.