We’re going to support Server Events for alt languages through ServiceStack’s new gRPC support which has a dedicated “Server Stream” rpc channel that’s specifically designed for persisten server communications like Server Events.

There’s a Dart Server Events example in the docs:

https://docs.servicestack.net/grpc#server-stream-grpc-services
https://docs.servicestack.net/grpc-dart

May look at improving the development UX in future with an “Adapter” of the gRPC stream to provide a declarative UX for registering handlers.