我想要与 304 响应一起发送哪些标头？

发布于 2024-07-15 08:42:44 字数 598 浏览 10 评论 0原文

当我发送 304 响应时。浏览器将如何解释我与 304 一起发送的其他标头？

例如，

header("HTTP/1.1 304 Not Modified");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + $offset) . " GMT");

这是否可以确保浏览器在 $offset 时间“用完”之前不会发送另一个条件 GET 请求（也不会发送任何请求）？

另外，其他标题呢？

我是否应该将这样的标头与 304: 一起发送：

header('Content-Type: text/html');

我是否必须发送：

header("Last-Modified:" . $modified);
header('Etag: ' . $etag);

以确保浏览器在下次 $offset“用完”时发送有条件的 GET 请求，或者只是保存旧的 Last Modified 和 Etag 值？

发送 304 响应标头时还需要注意其他事项吗？

原文

When I send a 304 response. How will the browser interpret other headers which I send together with the 304?

E.g.

header("HTTP/1.1 304 Not Modified");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + $offset) . " GMT");

Will this make sure the browser will not send another conditional GET request (nor any request) until $offset time has "run out"?

Also, what about other headers?

Should I send headers like this together with the 304:

header('Content-Type: text/html');

Do I have to send:

header("Last-Modified:" . $modified);
header('Etag: ' . $etag);

To make sure the browser sends a conditional GET request the next time the $offset has "run out" or does it simply save the old Last Modified and Etag values?

Are there other things I should be aware about when sending a 304 response header?

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℡Ms空城旧梦 2024-07-22 08:42:45

这篇博客文章帮助我驯服了“条件获取”野兽。

一个有趣的摘录（与本的回答部分矛盾）指出：

如果正常响应包含 ETag 标头，则该标头也必须包含在 304 响应中。
缓存标头（Expires、Cache-Control 和/或 Vary），如果它们的值可能与先前响应中发送的值不同。

这完全符合 RFC 2616 sec 10.3。 5.

低于 200 请求……

HTTP/1.1 200 OK
Server: nginx/0.8.52
Date: Thu, 18 Nov 2010 16:04:38 GMT
Content-Type: image/png
Last-Modified: Thu, 15 Oct 2009 02:04:11 GMT
Expires: Thu, 31 Dec 2010 02:04:11 GMT
Cache-Control: max-age=315360000
Accept-Ranges: bytes
Content-Length: 6394
Via: 1.1 proxyIR.my.corporate.proxy.name:8080 (IronPort-WSA/6.3.3-015)
Connection: keep-alive
Proxy-Connection: keep-alive
X-Junk: xxxxxxxxxxxxxxxx

及其最佳有效的 304 对应项。

HTTP/1.1 304 Not Modified
Server: nginx/0.8.52
Date: Thu, 18 Nov 2010 16:10:35 GMT
Expires: Thu, 31 Dec 2011 16:10:35 GMT
Cache-Control: max-age=315360000
Via: 1.1 proxyIR.my.corporate.proxy.name:8080 (IronPort-WSA/6.3.3-015)
Connection: keep-alive
Proxy-Connection: keep-alive
X-Junk: xxxxxxxxxxx

请注意，根据RFC-2616 14.21。

This blog post helped me a lot in order to tame the "conditional get" beast.

An interesting excerpt (which partially contradicts Ben's answer) states that:

If a normal response would have included an ETag header, that header must also be included in the 304 response.
Cache headers (Expires, Cache-Control, and/or Vary), if their values might differ from those sent in a previous response.

This is in complete accordance with the RFC 2616 sec 10.3.5.

Below a 200 request...

HTTP/1.1 200 OK
Server: nginx/0.8.52
Date: Thu, 18 Nov 2010 16:04:38 GMT
Content-Type: image/png
Last-Modified: Thu, 15 Oct 2009 02:04:11 GMT
Expires: Thu, 31 Dec 2010 02:04:11 GMT
Cache-Control: max-age=315360000
Accept-Ranges: bytes
Content-Length: 6394
Via: 1.1 proxyIR.my.corporate.proxy.name:8080 (IronPort-WSA/6.3.3-015)
Connection: keep-alive
Proxy-Connection: keep-alive
X-Junk: xxxxxxxxxxxxxxxx

...And its optimal valid 304 counterpart.

HTTP/1.1 304 Not Modified
Server: nginx/0.8.52
Date: Thu, 18 Nov 2010 16:10:35 GMT
Expires: Thu, 31 Dec 2011 16:10:35 GMT
Cache-Control: max-age=315360000
Via: 1.1 proxyIR.my.corporate.proxy.name:8080 (IronPort-WSA/6.3.3-015)
Connection: keep-alive
Proxy-Connection: keep-alive
X-Junk: xxxxxxxxxxx

Notice that the Expires header is at most Current Date + One Year as per RFC-2616 14.21.

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