Using ProtoBuf-net with gRPC

Question

I am trying to build a PoC at work that utilizes gRPC. The google document here takes us through a sample application. I was wondering if protobuf-net, and specifically protogen, had the capability to understand service definitions and classes necessary to perform gRPC calls? Or is this something being worked on? Would it work if I use google's protoc for client and server code generation(which involves the service definitions and RPC calls) and protobuf-net for my business objects.

Answer 1

protobuf-net.Grpc is now a thing... albeit in preview. When .NET Core 3 comes out, we should be able to make this available.

It is inspired by the WCF approach, so your service interfaces are defined via:

namespace Whatever {
    [ServiceContract]
    public interface IMyAmazingService {
        ValueTask<SearchResponse> SearchAsync(SearchRequest request);
        // ... etc
    }
}

Servers just implement the interface:

public class MyServer : IMyAmazingService {
    // ...
}

(how you host them depends on whether you're using ASP.NET Core, or the native/unmanaged gRPC libraries; both work)

and clients just request the interface:

var client = http.CreateGrpcService<IMyAmazingService>();
var result = await client.SearchAsync(query);

In the above case, this would be inferred to be the Whatever.MyAmazingService / Search service in gRPC terms, i.e.

package Whatever;
// ...
service MyAmazingService {
    rpc Search (SearchRequest) returns (SearchResponse) {}
}

but the service/method names can be configured more explicitly if you prefer. The above is a unary example; for unary operations, the result can be any of T, Task<T>, ValueTask<T> - or void / Task / ValueTask (which all map to .google.protobuf.Empty, as does a method without a suitable input parameter).

The streaming/duplex operations are inferred automatically if you use IAsyncEnumerable<T> (for some T) for the input parameter (client-streaming), the return type (server-streaming), or both (duplex).