  ProIO is a new event-oriented streaming data format which utilizes Google's
Protocol Buffers (protobuf) to be flexible and highly language-neutral. The
ProIO concept is described here along with its software implementations. The
performance of the ProIO concept for a dataset with Monte-Carlo event records
used in high-energy physics was benchmarked and compared/contrasted with ROOT
I/O. Various combinations of general-purpose compression and variable-length
integer encoding available in protobuf were used to investigate the
relationship between I/O performance and size-on-disk in a few key scenarios.
