IIS7 Web.Config Caching - what are the differences here, and how does it all come together?

问题

In IIS7 I've got the ability to set caching options. These options are added to my web.config as such...

    <caching maxCacheSize="262144">
        <profiles>
            <add extension=".png" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="00:00:30" />
            <add extension=".jpeg" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="00:00:30" />
            <add extension=".jpg" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="00:00:30" />
            <add extension=".css" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="00:00:30" />
            <add extension=".js" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="00:00:30" />
        </profiles>
    </caching>

However, I've also got the following for "caching"

    <staticContent>
        <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="90.00:00:00" />
        <remove fileExtension=".js" />
        <mimeMap fileExtension=".js" mimeType="text/javascript" />
    </staticContent>

What are the differences between these two configs? They are both nested in the <system.webServer> tag, so they're both valid for IIS7.

Also, what is the right approach when using these? I currently only use this is my static assets folder. I don't use this caching on anything else.

Thanks in advance.

回答1:

The main difference is that

• the first is for server-side caching of dynamic output such as aspx pages (basically keeps the page output in memory for subsequent requests). As @artem-vertiy's answer points out, using it for static content makes no sense.

• the second one is 'internet-side' : it is implemented by writing standard response headers, it tells both client browsers and public proxies how to manage cached files.

回答2:

I've noticed that people often confuse the things above and write articles where recommend things as in the first block, i.e. output caching for static resources

Output caching:

Output caching is unnecessary for static files, such as HTML, JPG, or GIF files, and can cause more memory overhead for dynamic ASP.NET or PHP pages that read from a database that changes frequently

Thus

<add extension=".png" ../>
<add extension=".jpeg" ../>
etc.

is useless at least when you don't have ashx http handler for .png or .jpeg etc.

来源：https://stackoverflow.com/questions/4841237/iis7-web-config-caching-what-are-the-differences-here-and-how-does-it-all-com