[rkalla]

If JSON compatibility is an issue, have you looked at UBJSON? http://ubjson.org/

May be a bit bigger than msgpack but is damn-near human readable even in its binary format and really easy to encode/decode. Also 1:1 compatibility with JSON.

Compatibility and simplicity were the core design tenantes. It may not be the right choice, just throwing it out there incase it helps.

Disclaimer: I am the author of the spec.

[chmike]

I looked at it. It's design process is not completed. One strong negative point is that it enforces big endian integer encoding.

Another one is that it doesn't use the value space of tags as efficiently as message pack. I would use the unused space to encode small string size in the tag since objects (associative arrays) have generally many short identifier strings as keys.

I sent these as comments and requests for change but didn't receive any response yet. I don't know how open its design process is.

[kiyoto]

Sounds cool. I would take a look. I think what this space (serializers) needs is objective/holistic evaluations of pros and cons of different approaches. (disclaimer: I am involved with MessagePack, although not a committer of any of its drivers).