How does Rails handle large-scale API federation and GraphQL aggregation layers?

Rails supports API federation by aggregating multiple services using GraphQL or BFF patterns.

API federation allows multiple backend services to be unified into a single API layer. Rails often acts as a GraphQL gateway that resolves fields from multiple microservices. This reduces frontend complexity but introduces challenges like N+1 resolution, caching, and resolver orchestration. DataLoader patterns are used to batch requests efficiently.