struct outboundrequest {
  int id = 1;
  optional struct[rpcrequest] rpc = 2;
  optional struct[healthprobe] probe = 3;
}

struct rpcrequest {
  string service = 1;
  string method = 2;
  optional int checksum = 3;
}

struct healthprobe {
  string service = 1;
}

struct inboundreply {
  int id = 1;
  optional struct[rpcreply] rpc = 2;
  optional struct[healthreply] health = 3;
}

struct rpcreply {
  int reply_code = 1;
  optional int checksum = 2;
}

struct healthreply {
  int good = 1;
}