I'd really love to see something like gRPC implemented over CBOR.

CBOR -- Concise Binary Object Notation -- http://cbor.io/ -- is all the performance of a binary protocol, with semantics basically identical to JSON.

I appreciate some of the things protobuf does to help you version, but I also do not appreciate the protobuf compiler as a dependency and a hurdle for contributors, or for wire debugging. CBOR has libraries in every major (and most minor) languages and works without a fuss with tiny overhead, both at runtime and in dependency size. It's pretty pleasant to work with.

There are two reasons why I think simpler binary packing libraries like CBOR, MsgPack, or BSON can't really match what Protobuf gives you:

- Assistance with schema evolution and versioning is one of the best parts about using Protobuf in an API. It is really like the best parts of XML and XML Schema (validation, documentation, interoperability) without any of the bloat.

- Working with code generation can be a pain to get working initially, but is very friendly when actually using real objects in code. There is no need to think about any representation on-the-wire... everything 'just works'. There is no need to ensure you don't accidentally serialize fields in the wrong order, or worry about encodings, etc.

Also, there is a binary decoder included with protoc that can print a debug decoding of any protobuf binary message, including integer tags for different fields. Wouldn't you have pretty much the same problems with dissection and debugging on-the-wire in CBOR?

It is really quite pleasant to use Protobuf for an API, I can see why Google is opinionated in including it as the only option with gRPC.

I don't find the utility to outweigh the PITA. I've been on both sides of the fence, and maintained large projects with heavy protobuf use.

I don't find the schema validation powerful enough. You still have to write correct code to migrate semantics. Avoiding incorrect reuse of field names is... nice, but also the most trivial of the problems.

(I do like schemas in theory. It's possible I haven't worked with good enough tooling around protobufs to really experience joy resulting from those schemas. The protos themselves certainly aren't guaranteed to be self-documenting, in some of my experiences.)

I don't find code generation results to be smooth in many languages. At $company, we switched through no less than three different final-stage code generators in search of a smooth experience. Not all of this was misplaced perfectionism: in some cases, it was driven by the sheer absurd method count verbosity in one code generator basically making it impossible to ship an application. (You've perhaps heard of the method count limits in early android? Bam.)

I don't think the debug decoding tools for protobuf are directly comparable to CBOR's interoperability with JSON. CBOR and JSON are literally interchangable. That means I can flip a bit in my program config and start using one instead of the other. Config files? Flip the bit. Network traffic not meant for humans? Flip the bit. Need to debug on the network? Flip the bit. Want to pipe it into other tools like `jq`? No problem. There's a whole ecosystem around JSON, and I like that ecosystem. Working with CBOR, I can have the best of both worlds.

Sometimes opinionated is good and powerful and really makes things streamlined in a way that contributes to the overall utility of the system. I don't think this is one of them. Almost every major feature of gRPC I'm interested in -- multiplexing, deadlines and cancellations, standard definitions for bidi streaming, etc -- has nothing to do with protobufs.

natch, I used "I" heavily in this comment, because I realize these are heavily subjective statements, and not everyone shares these opinions :)

gRPC can also use FlatBuffers, by the way.