摘要：
线上日志查到HTTP/1.1 412 Precondition Failed，一种追究下去，发现了很多关联的内容。1. 412的响应值代表了什么? 问：It is unclear to me when you should and should not return a HTTP 412: Precondition Failed, error for a web service? I am thinking of using it when validating data. For example, if a client POST's XML data and that data i 阅读全文
