Message protobuf schema

message Message {
    oneof content {
	    … 
    }
}

message PrePrepare {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Payload = 3;
    bytes Header = 4;
    bytes Metadata = 5;	
}

message Prepare {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Digest = 3;
}


message Commit {
    bytes Digest = 1;
    string Error = 2;
    bytes Signature = 3; 
}