Cap'n Proto includes both serialization (comparable to protobuf) and RPC (comparable to gRPC).
The main argument I've heard in favor of gRPC is that it is supported in more languages. Otherwise, I'm not sure what would make gRPC "much better at RPC" -- Cap'n Proto is actually much more expressive, and has features like capabilities and promise pipelining which gRPC lacks.
Do you remember the arguments you saw? I'd be curious to know what they were.
(Disclosure: I'm the author of Cap'n Proto and also Protobuf v2.)
The main argument I've heard in favor of gRPC is that it is supported in more languages. Otherwise, I'm not sure what would make gRPC "much better at RPC" -- Cap'n Proto is actually much more expressive, and has features like capabilities and promise pipelining which gRPC lacks.
Do you remember the arguments you saw? I'd be curious to know what they were.
(Disclosure: I'm the author of Cap'n Proto and also Protobuf v2.)