grpc

gRPC

gRPC is a modern open-source high-performance Remote Procedure Call (RPC) framework that can run in any environment. It uses Protocol Buffers (Protobuf) as its Interface Definition Language (IDL).

When to Use

• Microservices Communication: Low latency, high throughput internal traffic.
• Polyglot Environments: Service A (Go) talking to Service B (Java).
• Streaming: Bidirectional streaming of data (e.g., Real-time voice/video metadata).
• Strict Contracts: When you need strict type safety across services.

Quick Start

// service.proto
syntax = "proto3";

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

// Server (Go)
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}

Core Concepts

Protocol Buffers

Binary serialization format. Smaller and faster than JSON.

HTTP/2

gRPC runs on HTTP/2 by default, enabling Multiplexing (multiple requests over one connection) and Server Push.

Code Generation

You don't write client libraries manually. You generate them from the .proto file for any language (Go, Python, Java, Node, C#).

Common Patterns

gRPC-Web

Allows browser clients to talk to gRPC services via a proxy (Envoy).

Interceptors

Middleware for gRPC. Used for Logging, Auth, and Tracing.

Best Practices

Do:

• Use Linting (buf.build) for .proto files.
• Manage Backwards Compatibility carefully (never change field numbers).
• Use Deadlines/Timeouts on every call to prevent resource exhaustion.

Don't:

• Don't use gRPC for public browser APIs if simple REST/JSON suffices (proxying adds complexity).
• Don't ignore the Oneof feature for union types.

Troubleshooting

Error	Cause	Solution
Unavailable (14)	Server down or network issue.	Implement Exponential Backoff Retry.
Unimplemented (12)	Service method not found.	Re-generate code and check .proto sync.
Message too large	Payload exceeds limit (4MB default).	Increase limit or use Streaming.