\begin{lstlisting}[caption=The Redis and PostgreSQL schema (\texttt{schema.proto} file)., label={lst:protobuf-schema}]
syntax = "proto3";

package proto;

option java_package = "org.opendc.common";
option java_outer_classname = "ProtobufMetrics";

message ProtoExport {
  string timestamp = 1;
  string host_id = 2;
  int32 tasksactive = 3;
  double cpuutilization = 4;
  double energyusage = 5;
  double uptime = 6;
  double downtime = 7;
}\end{lstlisting}