Combine Multiple GraphQL APIs using Hasura's GraphQL Joins

The Hasura GraphQL Joins feature enables the creation of a unified GraphQL API by joining data from different GraphQL sources. It allows federating queries and mutations across multiple GraphQL services as if they were a single GraphQL schema without requiring extra code or changes to underlying APIs. There are four types of joins: Remote Schema to Remote Schema (RS-to-RS), Database to Database (DB-to-DB), Database to Remote Schema (DB-to-RS), and Remote Schema to Database (RS-to-DB). This article focuses on RS-to-RS Joins, which combine multiple GraphQL APIs via user-defined relationships. An example demonstrates joining a store service for handling orders with a fulfillment service for shipping using Hasura's GraphQL Joins feature without modifying the original APIs.