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iisiis-7gzipcontent-encoding

In IIS7, gzipped files do not stay that way

I have configured IIS7 to gzip static content.

http://www.coderjournal.com/2008/04/iis-7-compress-javascript-gzip/

However, the files don't "stay" gzipped.

Here's my use case:

  1. Request test.css file. It is not gzipped.
  2. Request it again within a few seconds. It is gzipped.
  3. Wait 5 minutes.
  4. Request test.css file again. It is not gzipped.

This doesn't make sense -- shouldn't the gzipped version of a static file be delivered on all subsequent requests, if the original did not change?

Note: I am using Firefox and Firebug to verify gzipped content by checking the Content-Encoding header.

Solution

  • According to this article:

    Changes to compression in IIS7 by Kanwaljeet Singla

    In IIS7, content is compressed depending on it's hit frequency which is configurable like this:

    <system.webServer>
  <serverRuntime enabled="true"
    frequentHitThreshold="5"
    frequentHitTimePeriod="00:00:20" />
</system.webServer>

    Maybe you're not hitting these thresholds?