Protobuf

Every public-facing API in the Composable Commerce Platform starts as a .proto file. The code — Go gRPC handlers, TypeScript SDK, HTTP routes, request validation, error codes — is generated from that contract. This article documents the conventions that make that system work. Answer-first: Internal services communicate via gRPC (type-safe, binary, ~7× faster than JSON over REST). External clients (browser, mobile app) use REST via the Gateway Service (port 8000). The proto file is the single source of truth for the API contract — and three proto conventions require special attention for engineers coming from Magento: the Money type (never use float for prices), cursor-based pagination (never use offset), and proto-level field validation (validation declared in the contract, not in business logic). ...

Why gRPC for Go Microservices? Answer-first: gRPC is the right choice for Go microservices when you need: binary-efficient serialization (Protobuf is 3–10× smaller than JSON), bidirectional streaming for real-time data, strongly-typed contracts across services, and sub-millisecond inter-service latency. Google, Uber, Netflix, and Square use gRPC as the primary inter-service communication protocol. This guide shows you how to build production-grade Go gRPC services from scratch. The key advantages over REST: gRPC REST/JSON Serialization Protobuf (binary, schema-enforced) JSON (text, schema-optional) Payload size 3–10× smaller Baseline Streaming Unary, Client, Server, Bidirectional HTTP/2 SSE (server-only), WebSocket (separate) Contract .proto file (language-agnostic codegen) OpenAPI (opt-in, often stale) Latency ~0.5ms p50 inter-service ~2–5ms p50 inter-service Browser support gRPC-Web (needs proxy) Native Best for Internal microservices, streaming Public APIs, browser clients Step 1: Define Your Service with Protobuf Create the contract first — Protobuf schema drives code generation for all languages. ...