gRPC
Proto Definition
// proto/product.proto
syntax = "proto3";
package product;
service ProductService {
rpc GetProduct(GetProductRequest) returns (Product);
rpc ListProducts(ListProductsRequest) returns (stream Product); // Server streaming
rpc UploadProducts(stream Product) returns (UploadResponse); // Client streaming
rpc SyncProducts(stream SyncRequest) returns (stream SyncResponse); // Bidirectional
}
message Product {
string id = 1;
string name = 2;
double price = 3;
repeated string tags = 4;
google.protobuf.Timestamp created_at = 5;
}
message GetProductRequest { string id = 1; }
message ListProductsRequest {
int32 page_size = 1;
string page_token = 2;
}
message UploadResponse { int32 count = 1; }
Node.js (@grpc/grpc-js)
import * as grpc from '@grpc/grpc-js';
import * as protoLoader from '@grpc/proto-loader';
const packageDef = protoLoader.loadSync('proto/product.proto');
const proto = grpc.loadPackageDefinition(packageDef).product as any;
// Server
const server = new grpc.Server();
server.addService(proto.ProductService.service, {
getProduct: (call: any, callback: any) => {
const product = db.findProduct(call.request.id);
callback(null, product);
},
listProducts: (call: any) => {
const products = db.listProducts(call.request);
for (const p of products) call.write(p);
call.end();
},
});
server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), () => {
console.log('gRPC server running on port 50051');
});
// Client
const client = new proto.ProductService('localhost:50051', grpc.credentials.createInsecure());
client.getProduct({ id: '123' }, (err: any, product: any) => {
console.log(product);
});
Go (google.golang.org/grpc)
// Server implementation
type productServer struct {
pb.UnimplementedProductServiceServer
}
func (s *productServer) GetProduct(ctx context.Context, req *pb.GetProductRequest) (*pb.Product, error) {
product, err := s.db.FindProduct(req.Id)
if err != nil {
return nil, status.Errorf(codes.NotFound, "product not found: %s", req.Id)
}
return product, nil
}
func main() {
lis, _ := net.Listen("tcp", ":50051")
s := grpc.NewServer(
grpc.UnaryInterceptor(loggingInterceptor),
)
pb.RegisterProductServiceServer(s, &productServer{})
s.Serve(lis)
}
Error Handling
// Use standard gRPC status codes
import { status } from '@grpc/grpc-js';
callback({
code: status.NOT_FOUND,
message: `Product ${id} not found`,
});
callback({
code: status.INVALID_ARGUMENT,
message: 'Product name is required',
});
| Code | Use When |
|---|
NOT_FOUND | Resource doesn't exist |
INVALID_ARGUMENT | Bad request data |
PERMISSION_DENIED | Insufficient permissions |
UNAUTHENTICATED | Missing/invalid credentials |
UNAVAILABLE | Service temporarily down (retryable) |
Anti-Patterns
| Anti-Pattern | Fix |
|---|
| Returning HTTP status codes | Use gRPC status codes |
| No deadline/timeout on calls | Always set deadline on client calls |
| Large messages (>4MB default) | Stream large data, or increase maxReceiveMessageLength |
| No interceptors for auth/logging | Use unary/stream interceptors |
| Proto files not versioned | Keep.proto in source control, use package versioning |
Production Checklist
- TLS certificates configured
- Health check service (gRPC health checking protocol)
- Interceptors for auth, logging, metrics
- Deadlines set on all client calls
- Proto file versioning strategy
- Load balancing configured (client-side or L7)
