The Couch server goes from binary Erlang terms (our default internal representation) to MessagePack right away, skipping all textual JSON generation. All the REST methods are still there, the body is just sent in MessagePack format with an application/x-msgpack header https://github.com/timanglade/couchdb/commit/b601286dae04bdc...
Ah! That is exactly what I was hoping for (skipping the JSON in/out cycle server-side).
Keeping the HTTP protocol in this case is fine for me and not require any unexpected changes to Couch. I hope that binary format work can be make configurable in the future with other formats supported.
