RPC

Calling a function on another machine as if it were local.

Backend Engineer · Mid-level Frontend Engineer · Mid-level Data Engineer · Mid-level

Also known as: rpc, remote procedure call, remote procedure calls

RPC (remote procedure call) invokes a function on another machine with local-call syntax: stubs marshal arguments, ship them over the network, and return the result. The promise is transparency — distribution hidden behind a function call. The peril is the same transparency: networks fail, stall and cost in ways local calls never do.

client: getUser(7)  →  stub → network → server executes → result returns

Modern incarnations span JSON-RPC, XML-RPC’s descendants, and typed frameworks (gRPC, tRPC). They shine for service-to-service operations and actions that aren’t resource-shaped — verbs, not nouns.

The classic mistakes:

Forgetting the fallacies. Latency isn’t zero, bandwidth isn’t infinite, the network isn’t reliable — every RPC assumption that “it’s just a function call” eventually bills you. Timeouts, retries and deadlines are mandatory.
Chatty interfaces. Getters-per-field over RPC multiply round trips catastrophically. Coarsen the interface: fewer, bulkier calls.
Hiding errors. Mapping every failure to a local exception type loses retryability signals. Preserve status, deadlines and retry guidance across the boundary.
No deadlines. An RPC without a deadline inherits the caller’s patience — usually infinite. Propagate deadlines end to end.
Versioning by redeploy. Changing signatures without a compatibility story breaks callers silently. Version, evolve additively, or share types from one source.
Using RPC where REST fits. Resource CRUD with caching needs is better served by HTTP semantics. RPC for actions, REST for resources — roughly.
Ignoring observability. Transparent calls hide in profiles; instrument RPC boundaries with traces and latency histograms or they become invisible slowdowns.

When to choose it: internal service calls and action-oriented APIs where typed functions beat resource modelling. Respect the network’s reality — timeouts, coarse calls, explicit errors — and RPC’s convenience stops being a trap.