This sounds very similar in concept to Cap'n Proto, and given how much hard-earned experience Kenton has and how much time he's put into it, I'd put my bets on Cap'n Proto if you're looking for something in this design space.<p>I haven't looked at SBE in detail, but given the high-level description I expect it would have a similar set of trade-offs vs. Protocol Buffers as Cap'n Proto does: it will have unparalleled serialize/deserialize performance (since they are basically no-ops), but sparse messages (where only a few of many defined fields are set) will be arbitrarily larger than protobufs, so a separate compression step will be necessary to be size-competitive, at which point some of the speed advantage is lost.