protobuf中文教程（第一篇） https://www.cnblogs.com/chenyangyao/p/5422044.html
Protobuf3语言指南 https://blog.csdn.net/u011518120/article/details/54604615
[译]Protobuf 语法指南 https://colobu.com/2015/01/07/Protobuf-language-guide/