1.
dubbo study entry (a) ----- distributed basic theory, infrastructure development and rpc, dubbo core concepts
https://www.cnblogs.com/alimayun/p/10982650.html
2.
Getting dubbo official documents
https://www.jianshu.com/p/c9d30c8f856f
http://dubbo.apache.org/zh-cn/docs/user/references/xml/dubbo-reference.html