One potentially nice thing about formats like Cap'n Proto is that they don't eagerly parse the message. You can just lazily grab the values you care about, whic

One potentially nice thing about formats like Cap'n Proto is that they don't eagerly parse the message. You can just lazily grab the values you care about, which can be a big performance win if you typically only care about a few fields out of a larger message. That's impossible with text-based formats like XML and JSON, because everything is fractally variable-length.