Lesson 18 of 40 Web Development Advanced 45 min

gRPC & Protobuf Services

Build high-performance, strongly-typed microservice communication with gRPC in .NET 10 and VS 2026's proto tooling.

Part 1: Proto File Definition

// orders.proto
syntax = "proto3";
package orders;

service OrderService {
  rpc GetOrder (GetOrderRequest) returns (OrderResponse);
  rpc StreamOrders (StreamRequest) returns (stream OrderResponse);
}

Part 2: Server Implementation

public class OrderGrpcService : OrderService.OrderServiceBase
{
  public override async Task<OrderResponse> GetOrder(
    GetOrderRequest request, ServerCallContext context)
  {
    var order = await _service.GetByIdAsync(request.Id);
    return order.ToProto();
  }
}

Part 3: Client-Side Streaming

using var stream = client.StreamOrders(new StreamRequest());
await foreach (var order in stream.ResponseStream.ReadAllAsync())
{
  Console.WriteLine($"Order: {order.Id} - {order.Status}");
}

Part 4: gRPC-Web for Browsers

gRPC-Web lets browsers call gRPC services via HTTP/1.1:

builder.Services.AddGrpcWeb(o => o.DefaultEnabled = true);
app.UseGrpcWeb();

// JS client uses @improbable-eng/grpc-web