http - 我应该指定 "Vary: If-None-Match, If-Modified-Since"吗？

Question

RFC 7231 :

The "Vary" header field in a response describes what parts of a
request message, aside from the method, Host header field, and
request target, might influence the origin server's process for
selecting and representing this response.

Answer 1

没有。

RFC says :

An origin server SHOULD send a Vary header field when its algorithmfor selecting a representation varies based on aspects of the requestmessage other than the method and request target

在这种情况下，表示形式不是由这些 header 的值决定的。它们用于决定是否应发送正文。

作为提示:

For example, there is noneed to send the Authorization field name in Vary because reuseacross users is constrained by the field definition

对于条件请求字段也是如此。