How do you build fast gRPC services in .NET, and what do .proto files do?

Short answer

They define strongly typed service and message contracts in .proto files, and the C# compiler generates fast base classes that communicate over HTTP/2 using compact binary serialization.

Explanation

gRPC is well suited to direct communication between .NET Microservices. Protocol Buffers reduce network payload size and serialization time compared with JSON (the improvement depends on the data). gRPC also natively supports bidirectional streaming (Client & Server Streaming) and strongly defined contracts across languages.

Code example

// Greeter.proto
syntax = "proto3";
service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}
message HelloRequest { string name = 1; }
message HelloReply { string message = 1; }

Common mistakes

• Reusing field numbers or changing existing field numbers in a .proto file, breaking binary compatibility with older versions.

Follow-up questions

• What is .NET Aspire, and how does it simplify building and monitoring distributed Cloud-Native applications?

Sources

• Microsoft Learn — Overview for gRPC on .NET