What does a field mask do in an API?
It lets a caller name exactly which fields of a resource it wants back, so a shared endpoint can serve a lean response to one client and a rich one to another. It controls payload size and downstream fan-out without creating a new endpoint per client.
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Backends for Frontends, and What Comes After: Value-Added Services and Domain GatewaysBFFs fix client sprawl, then duplicate authorization logic across themselves. The three-layer fix: edge, value-added services, and per-domain gateways.
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