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缓存供稿，仅在更改供稿时刷新

[英]Cache feed and only refresh when feed is changed

原文 2010-08-13 09:14:43 1 1 php/ caching/ feed

Over at rsscache they have a way of refreshing the cache only when the feed has changed. 在rsscache上，它们只有在feed更改时才有刷新缓存的方法。 Unfortunately its .Net. 不幸的是它的.Net。

I would like to know what approach I should take to achieve this in php. 我想知道我应该采取什么方法在php中实现这一目标。

How are changes in the feed detected? 如何检测到提要中的变化？ Simply by a timestamp (time node in the beginning of the feed)? 只是通过时间戳记（提要开头的时间节点）？

My feed would be a yahoo pipe that has mixed many feeds together. 我的提要是将许多提要混合在一起的Yahoo管道。 So either the yahoo feed must generate a combined timestamp, or my cache mechanism must automagically detect if the pipe has changed. 因此，要么yahoo提要必须生成组合的时间戳记，要么我的缓存机制必须自动检测管道是否已更改。

1 个解决方案

You have to: 你必须：

Store when the content you have cache was last stored (read the server's Last-modified header). 存储您上次缓存的内容的最后存储时间（读取服务器的Last-modified标头）。
Make conditional GET requests (send the header If-modified-since ). 发出条件GET请求（发送标头If-modified-since ）。

The server will either respond with 200 (OK) and the content or 304 (Not Modified) and an empty response body. 服务器将以200 （确定）和内容或304 （未修改）和空的响应正文进行响应。

See RFC 2616 . 参见RFC 2616 。