IIS Static Compression does not Gzip, or cache files

Question

I have an ASP.NET website that I'm trying to enable Static Compression for. My website has the following compression configuration.

<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" staticCompressionEnableCpuUsage="0" staticCompressionDisableCpuUsage="100" staticCompressionIgnoreHitFrequency="true">
  <clear/>
  <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="10" dynamicCompressionLevel="3" />
  <scheme name="deflate" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="10" dynamicCompressionLevel="3" />
  <staticTypes>
    <clear/>
    <add mimeType="text/*" enabled="true" />
    <add mimeType="message/*" enabled="true" />
    <add mimeType="application/x-javascript" enabled="true" />
    <add mimeType="application/javascript" enabled="true" />
    <add mimeType="*/*" enabled="false" />
  </staticTypes>
</httpCompression>
<urlCompression doStaticCompression="true" doDynamicCompression="false"  dynamicCompressionBeforeCache="false" />

I do not want to enable dynamic compression. According to Microsoft documentation,

Unlike static compression, IIS 7 performs dynamic compression each time a client requests the content, but the compressed version is not cached to disk.

My web server is fairly heavily loaded with processes, so this would be an unwanted burden. By Static Compression is appealing because the compressed files are cached on disk.

However, even after continuous refreshing of the localhost page (Ctrl+F5), and waiting 15+minutes on watching the compression directory, nothing is being cached.

Also, none of the relevant files (css/js/html) are being returned with an gzip compression header.

Both dynamic and static compression are installed. Dynamic is turned off. If I turn on dynamic compression, I start seeing the gzip HTTP response headers come back.

What am I missing? Why does Static Compression refuse to work?

IIS 10

Answer 1

I had this problem and tracked it down to a bad URL Rewrite rule. The static assets were living in C:\inetpub\wwwroot\MyProject\wwwroot and the rewrite rule was changing ^assets/(.*) to ./{R:1}, so IIS was looking at the top of MyProject and not finding the file. But then when it handed the request off to the .Net app, the app would see the file and serve it. So the two symptoms were:

• gzip worked only when dynamic compression was enabled (because the .Net app was serving the files).
• turning off runAllManagedModulesForAllRequests (on the modules element) caused our static files to become 404 errors---basically surfacing the problem of IIS not seeing the file.

To fix it I changed the rewrite rule from ./{R:1} to ./wwwroot/{R:1}.

Answer 2

Have you looked at this: https://blogs.msdn.microsoft.com/friis/2017/09/05/iis-dynamic-compression-and-new-dynamic-compression-features-in-iis-10/

Theres not much context to see from your question ... but for me this worked.

Cached by asp.net mvc, because it's a bundle of multiple js files. I guess the IIS can see it's not a static file on disk on thats the reason it's dynamic.

There also help to see what id actually does with your js file to find out why it's not doing compression in the link I posted.

I also saw a line in the link you posted:

Unlike static compression, IIS 7 performs dynamic compression each time a client requests the content, but the compressed version is not cached to disk. This change is made because of the primary difference between static and dynamic content. Static content does not change. However, dynamic content is typically content that is created by an application and therefore changes often, such as Active Server Pages (ASP) or ASP.NET content. Since dynamic content should change often, IIS 7 does not cache it.

Also try to read this post: https://forums.iis.net/t/1071156.aspx