API / Apollo Gateway Interview questions
What is the difference between Apollo Server and Apollo Gateway?
Apollo Server is a standalone GraphQL server: you give it a schema and resolvers and it executes queries against them directly. Apollo Gateway is not a full server on its own — it's a package that plugs into an Apollo Server instance so that instance behaves as an orchestrator instead of a resolver, forwarding pieces of each query to other services.
| Apollo Server | Apollo Gateway |
| Resolves fields itself using its own resolvers | Delegates field resolution to subgraph services |
| Owns a single schema | Composes many subgraph schemas into one supergraph |
| Used to build a subgraph itself | Used to run the entry-point gateway in front of subgraphs |
In a typical federated setup you actually use both: each subgraph is its own Apollo Server, and the gateway is a separate Apollo Server instance configured with the ApolloGateway executor instead of local resolvers.
What best distinguishes Apollo Gateway from a plain Apollo Server instance?
In a typical federated setup, what role does Apollo Server play at the subgraph level?
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