There are dozens, if not hundreds of serialization libraries. None of them are going to compare to something like sending a raw struct on the wire, if you need absolute performance. Probably the biggest advantage of things like grpc, flatbuffers, capnproto, etc, are they provide serialization libraries for many different languages. Sending a raw struct will be up to the implementer to get the other side correct.
And by sticking with the serialization libraries with higher performance, like flatbuffers and capnproto, you also lose a little bit of future flexibility, since its typically harder to change the format of these structures compared to higher level libraries.
> None of them are going to compare to something like sending a raw struct on the wire, if you need absolute performance.
I don't know about that.
For simple flat structs containing integers only (no pointers), Cap'n Proto is nearly identical to raw structs.
For complex structures with pointers, sending raw structs doesn't work.
Admittedly you may suffer unwanted code bloat linking in the Cap'n Proto library if all you really want to do is send a flat, raw struct.
> And by sticking with the serialization libraries with higher performance, like flatbuffers and capnproto, you also lose a little bit of future flexibility, since its typically harder to change the format of these structures compared to higher level libraries.
I disagree with this. Cap'n Proto's compatibility story is essentially the same as Protobuf and JSON: You can add new fields and old programs will ignore them.
(I suspect Flatbuffers is also similar but I haven't looked at it in a long time.)
And by sticking with the serialization libraries with higher performance, like flatbuffers and capnproto, you also lose a little bit of future flexibility, since its typically harder to change the format of these structures compared to higher level libraries.