gRPC — faster communication between microservices

Our microservices communicate via REST with JSON. It works, but JSON serialization is slow, there’s no schema, and streaming is a hack. gRPC solves all three problems.

What is gRPC¶

An RPC framework from Google. Protocol Buffers for serialization (binary, compact, typed) and HTTP/2 as transport (multiplexing, streaming).

syntax = "proto3";
service OrderService {
  rpc CreateOrder (CreateOrderRequest) returns (Order);
  rpc StreamUpdates (GetOrderRequest) returns (stream OrderUpdate);
}
message Order {
  string id = 1;
  string status = 2;
}

Performance difference¶

• Serialization: protobuf 3-5x faster than JSON
• Payload: protobuf 2-3x smaller
• Latency: gRPC ~30% lower thanks to HTTP/2
• Streaming: gRPC native

When to use gRPC, when REST¶

gRPC: internal service-to-service, high-throughput streaming. REST: public APIs, browsers, third parties. Envoy can handle gRPC-JSON transcoding at system boundaries.

gRPC is ideal for internal microservices¶

For public APIs use REST, for internal communication use gRPC — typed contracts, high performance, and native streaming. We’re migrating gradually.