blocks|key|743635|text|只需适当地设置Last-Modified标头，并让客户端决定它是否过时。陈旧数据的上次修改日期将比“正常”日期更早。对于最新数据，请保持Last-Modified+header最新。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|743636|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Simply set the Last-Modified header appropriately, and let the client decide if it's stale. Stale data will have the Last-Modified date farther back than "normal". For fresh data, keep the Last-Modified header current.

blocks|key|4637292|text|在马克·诺丁汉的“caching+article”中，他说|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4637293|4637294|在某些情况下-例如，当它与网络断开连接时-缓存可以提供过时的响应，而不需要与源站进行检查。|blockquote|4637295|4637296|4637297|在您的例子中，您的web服务的行为就像一个中间缓存。|4637298|当表示已过期或Max-age标头已过时，表示已过时。因此，如果您返回一个包含|4637299|Cache-control:+Max-age=0|code-block|syntax|javascript|4637300|那么你实际上是在说你返回的表示已经过时了。假设当您从“系统C”检索表示时，可以认为数据在一段非零的时间内是最新的，您的web服务可以返回这样的表示：|4637301|Cache-control:+Max-age=3600|4637302|客户端可以检查最大年龄==+0的高速缓存控制报头，以确定表示在第一次被检索时是否陈旧。|4637303|entityMap|0|LINK|mutability|MUTABLE|url|http://www.mnot.net/cache_docs/^0|9|F|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@$A|17|B|18|1|19]]|C|$]]|$1|D|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|1B|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|1E|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|1F|8|@]|9|@]|C|$]]|$1|N|3|O|5|P|7|1G|8|@]|9|@]|C|$Q|R]]|$1|S|3|T|5|6|7|1H|8|@]|9|@]|C|$]]|$1|U|3|V|5|P|7|1I|8|@]|9|@]|C|$Q|R]]|$1|W|3|X|5|6|7|1J|8|@]|9|@]|C|$]]|$1|Y|3|-4|5|6|7|1K|8|@]|9|@]|C|$]]]|Z|$10|$5|11|12|13|C|$14|15]]]]

In Mark Nottingham's <a href="http://www.mnot.net/cache_docs/" rel="nofollow">caching article</a> he says

<blockquote>
 Under certain circumstances — for example, when it’s disconnected from
 a network — a cache can serve stale responses without checking with
 the origin server.
</blockquote>

In your case, your web service is behaving like an intermediary cache.

A representation is stale when either it's Expires or Max-age header has passed. Therefore if you returned a representation with

<pre><code>Cache-control: Max-age=0
</code></pre>

Then you are effectively saying that the representation you are returning is already stale. Assuming that when you retrieve representations from the "System C" that the data can be considered fresh for some non-zero amount of time, your web service can return representations with something like,

<pre><code>Cache-control: Max-age=3600
</code></pre>

The client can check cache control header for max-age == 0 to determine if the representation was stale when it was first retrieved or not.

blocks|key|4637342|text|如果你提供的是陈旧的回复，RFC-2616说：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4637343|4637344|如果存储的响应由于客户端和源服务器的最严格的新鲜性要求而不是“足够新鲜”，则在仔细考虑的情况下，高速缓存仍然可以返回具有适当警告报头的响应(参见13.1.5和14.46节)，除非这样的响应被禁止(例如，通过"no-store“高速缓存指令，或者通过"no-+cache”高速缓存请求-指令；参见第14.9节)。|blockquote|4637345|4637346|4637347|换句话说，服务200OK是非常好的。|4637348|entityMap|0|LINK|mutability|MUTABLE|url|https://www.rfc-editor.org/rfc/rfc2616#section-13.1.1^0|D|8|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|D|3|-4|5|6|7|X|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|Y|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|Z|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|12|8|@]|9|@]|C|$]]]|M|$N|$5|O|P|Q|C|$R|S]]]]

If you are serving stale responses <a href="https://www.rfc-editor.org/rfc/rfc2616#section-13.1.1" rel="nofollow noreferrer">RFC-2616</a> says:
<blockquote>
If a stored response is not &quot;fresh enough&quot; by the most
restrictive freshness requirement of both the client and the
origin server, in carefully considered circumstances the cache
MAY still return the response with the appropriate Warning
header (see section 13.1.5 and 14.46), unless such a response
is prohibited (e.g., by a &quot;no-store&quot; cache-directive, or by a
&quot;no-cache&quot; cache-request-directive; see section 14.9).
</blockquote>
In other words, serving 200 OK is perfectly fine.

blocks|key|740209|text|我将返回200OK和一个适当的特定于应用程序的响应。似乎没有合适的其他HTTP状态代码，因为是否以及如何使用响应的决定是传递给客户端的。我还建议不要使用标准HTTP缓存控制标头来实现此目的。我只会使用它们来控制第三方(中间层和客户端)缓存。使用这些头来传递特定于应用程序的信息，这将应用程序逻辑与缓存控制联系在一起。虽然这可能不是一目了然的，但独立发展应用程序逻辑和缓存策略的能力确实有长期的好处。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|740210|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I would return 200 OK and an appropriate application-specific response. No other HTTP status code seems appropriate, because the decision if and how to use the response is being passed to the client. I would also advise against using standard HTTP cache control headers for this purpose. I would use them only to control third-party (intermediary and client) caches. Using these headers to communicate application-specific information uneccesarily ties application logic to cache control. While it might not be immediately obvious, there are real long-term benefits in the ability to independently evolve application logic and caching strategy.

The scenario is: I'm implementing a RESTful web-service that will act as a cache to entities stored on remote a C system. One of the web-service's requirements is that, when the remote C system is offline, it would answer GET requests with the last cached data, but flagging it as "stale".

The way I was planning to flag the data as stale was returning a HTTP status code other than 200 (OK). I considered using 503 (service unavailable), but I believe that it would make some C#/Java HTTP clients throw exceptions, and that would indirectly force the users to use exceptions for control flow.

Can you suggest a more appropriate status code? Or should I just return 200 and add a staleness flag to the response body? Another option would be defining a separate resource that informs the connectivity state, and let the clients handle that separately.

What HTTP status code should I use for a GET request that may return stale data?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

场景是:我正在实现一个RESTful web服务，它将充当存储在远程C系统上的实体的缓存。web服务的需求之一是，当远程C系统离线时，它将使用最后缓存的数据响应GET请求，但将其标记为“陈旧”。我计划将数据标记为陈旧的方法是返回一个HTTP状态码，而不是200 (OK)。我考虑使用503 (服务不可用)，但我相信它会使...

问对于可能返回陈旧数据的GET请求，我应该使用什么HTTP状态代码？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问对于可能返回陈旧数据的GET请求，我应该使用什么HTTP状态代码？EN