Question

i enable gzip for javascript file in my iis settings, here ‘s the corresponding config section.

<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files">
        <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="10" dynamicCompressionLevel="8" />
        <dynamicTypes>
            <add mimeType="text/*" enabled="true" />
            <add mimeType="message/*" enabled="true" />
  <add mimeType="application/soap+msbin1" enabled="true" />
            <add mimeType="*/*" enabled="false" />
        </dynamicTypes>
        <staticTypes>
            <add mimeType="text/*" enabled="true" />
            <add mimeType="message/*" enabled="true" />
            <add mimeType="application/javascript" enabled="true" />
  <add mimeType="application/x-javascript" enabled="true" />
            <add mimeType="*/*" enabled="false" />
        </staticTypes>
    </httpCompression>

currently, when i download my js file, it seems that sometimes server return the gzip one, and sometimes not. i dont know why, and how to debug that.

If a file is already gzipped, it should be cached in local disk, and next time someone visit that file again, iis kernel should return the cache gzip file directly without compressing it again. Is that right?

Answer 1

jaf, i figure it out myself, there might be some bug in iis. you can set the frequenthitthreshold option to force the script file to always gzip the file.
i write a post about this bug, but it’s in chinese, here ‘s the google translated version
Why gzip not work in IIS7?