Overview

gRPC is a remote-procedure-call framework commonly used for typed service-to- service APIs. A Protocol Buffers schema defines messages and service methods; code generators create client and server bindings for supported languages.

gRPC typically uses HTTP/2 as its transport. HTTP/2 provides multiplexed streams, header compression, and flow control. Server-Sent Events and sticky sessions are not gRPC or HTTP/2 features.

Communication patterns:

• unary: one request and one response;
• server streaming: one request and a stream of responses;
• client streaming: a stream of requests and one response;
• bidirectional streaming: independent request and response streams.

Minimal contract

syntax = "proto3";

package catalog.v1;

option go_package = "example.com/catalog/gen/catalog/v1;catalogv1";

service CatalogService {
  rpc GetProduct(GetProductRequest) returns (GetProductResponse);
}

message GetProductRequest {
  string id = 1;
}

message GetProductResponse {
  string id = 1;
  string name = 2;
}

Field numbers are part of the wire contract. Do not reuse a removed field number; reserve it and its old name. Prefer additive changes, propagate deadlines through context.Context, and map expected failures to appropriate gRPC status codes.

Operational checklist

• Enable TLS and authenticate callers.
• Set client deadlines; a server cannot infer a useful business timeout.
• Retry only idempotent calls and use bounded backoff.
• Configure message-size limits intentionally.
• Export latency, status-code, and saturation metrics.
• Use health checking and graceful shutdown for rolling deployments.

Further reading: gRPC concepts and gRPC Go quick start.