grpc-serviceslisted

# gRPC services gRPC uses Protocol Buffers over HTTP/2 for fast, strongly-typed service-to-service communication with generated clients in every language. It shines for internal microservice APIs where performance and contract strictness matter; the design work is the proto contract, its evolution, and using the streaming and deadline features correctly. ## Method 1. **Design the proto as the contract, carefully.** The `.proto` file defines the service, methods, and message types, and generates clients and servers in every language (see openapi-contracts' spec-first ethic, gRPC edition): so the proto is the API. Design messages for the domain, group related RPCs into services, and treat the proto with the same review rigor as any public contract. 2. **Evolve protos with the compatibility rules.** Field numbers are the wire identity and are permanent: never reuse or change a field's number; add new fields with new numbers (old clients ignore them), reserve removed field numbers, and never change a field's type (see schema- evolution, api-change-management: Protobuf's rules are strict and mechanical). Following them gives backward and forward compatibility; breaking them corrupts data silently. 3. **Choose the right RPC pattern.** Unary (request- response, the default), server streaming (one request, stream of responses: feeds, large result sets), client streaming (stream up, one response: uploads, batched ingestion),