Agreed! I would also take it one step further and suggest that these libraries are "type systems for data interchange." Say you want to stuff your logs into a

Agreed! I would also take it one step further and suggest that these libraries are "type systems for data interchange." Say you want to stuff your logs into a database like BigQuery (which I work on at Google) for later analysis. What is the schema of your logs? I dream of a world where the logfile->JSON parser can use the same schema definition as the database itself, so there is no glue/conversion required to turn one into the other. Likewise I think these schema languages are ideal for defining ASTs and other compiler infrastructure. Wouldn't it be cool if you could dump your AST into a database and run queries over it? Again, the goal is to do this without requiring a big schema mapping / transformation first. I believe in this vision, and I think Protocol Buffer schemas fit the bill as something that can be usefully applied to much more than just Protocol Buffers. The first step I'm taking towards this is making JSON a first-class citizen in my library.