API / Apollo Gateway Interview questions
What is Apollo Gateway?
Apollo Gateway is the @apollo/gateway npm package that extends Apollo Server so it can act as a single entry point for a federated GraphQL architecture. Instead of resolving data itself, it takes an incoming query, breaks it into a query plan, and dispatches the underlying pieces to the individual subgraph services that actually own the data.
It was Apollo's original JavaScript runtime for Federation, shipped alongside Apollo Federation 1. It's still functional and supported today, but Apollo now points new production deployments toward the Rust-based Apollo Router, which offers substantially better throughput and lower latency.
In short: Gateway doesn't hold any business data itself — it composes a schema from many services and routes each client query to the right ones.
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