All 15 gRPC Services questions
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What is gRPC, and how does it differ from a traditional REST/JSON API? What is the purpose of the ServerCallContext parameter present in every gRPC server method, and what information does it expose? How do you define a gRPC service contract using Protocol Buffers (.proto files), and how does code generation work in a .NET project? What is gRPC-Web, and why is it needed for calling gRPC services directly from a browser-based JavaScript client? How do you implement server-streaming gRPC using C#'s IAsyncEnumerable<T> or IServerStreamWriter<T>? What is protobuf field numbering, and why must you never reuse or renumber a field once a message definition has shipped to production? How would you version a gRPC service's contract while maintaining backward compatibility with existing clients? How does client-side load balancing work for gRPC when calling a service with multiple backend instances, without a dedicated load balancer? What are the four types of gRPC service methods (unary, server streaming, client streaming, bidirectional streaming), and when is each appropriate? How does gRPC handle errors and status codes, and how does this differ from HTTP status codes in REST?
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How do you implement a gRPC server method in ASP.NET Core, and how does it integrate with the standard hosting model?

Intermediate

Answer

A gRPC service class extends the code-generated base class (from the .proto file) and overrides its virtual RPC methods, registered via MapGrpcService<T>() in the endpoint routing configuration -- gRPC services run on top of the same Kestrel/ASP.NET Core hosting infrastructure as regular web APIs, meaning they benefit from the same middleware pipeline, dependency injection, logging, and configuration systems.
public class GreeterService : Greeter.GreeterBase {
    public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context) {
        return Task.FromResult(new HelloReply { Message = $"Hello, {request.Name}" });
    }
}

// Program.cs
builder.Services.AddGrpc();
app.MapGrpcService<GreeterService>();
Real-world example A team adds a gRPC service alongside their existing REST controllers in the same ASP.NET Core application, both benefiting from the same registered authentication middleware and dependency-injected services without any duplicated configuration.

Common follow-ups: Can a single ASP.NET Core app serve both REST and gRPC endpoints simultaneously?;How does dependency injection work within a gRPC service method?

Dependency Injection;ASP.NET Core Middleware & Request Pipeline
All 15 gRPC Services questions