[C#] Close / reject RPC from server side

[Joseph Vaughan]

I have a few instances where I'd like my gRPC server to reject an RPC call using the newly introduced Interceptors functionality. I've read the documentation and can see that this is a desired piece of functionality (Cancelling RPCs). I can see the functionality is available within the Java API (ServerCall.java) which looks perfect for what I'd like to do (Cancel the RPC and return one of the internal gRPC status codes). The best solution I can find right now for a C# server is to raise an RpcException with a Status, however I'd like to avoid the use of exceptions for common control flow where possible.

Ideally I'm looking for the same functionality as demonstrated here: https://github.com/grpc/grpc-java/issues/779#issuecomment-130365950

Am I missing something on the C# side where I can already do this, and if not, are there plans to introduce a similar API?

Thanks,
Joseph.

[Jan Tattermusch]

In C# status server handlers (and also in interceptors on the serverside), you can set the resulting status without throwing an exception by setting ServerCallContext's "Status" property.

https://github.com/grpc/grpc/blob/1c73e2c53ddecf3bd45f1c28d23a895fc7cd6e12/src/csharp/Grpc.Core/ServerCallContext.cs#L155

call.Status = new Status(StatusCode.WhateverYouWant, "");

// and then return from the server side handler.

A test that demonstrates this is here: https://github.com/grpc/grpc/blob/1c73e2c53ddecf3bd45f1c28d23a895fc7cd6e12/src/csharp/Grpc.Core.Tests/ClientServerTest.cs#L129

[Joseph Vaughan]

Thanks Jan, I just got to test this out and this is exactly what I was after.