, identifying the specific
version of the returned resource. The user should be able to check for
staleness in their subsequent requests by supplying the value in the
If-None-Match header.
在所有的請求中帶上 ETag 頭 , 用于識別特定版本的返回資源。用戶可以在隨后的請求中通過提供 If-None-Match頭的值來檢查內(nèi)容是否過期。