Compressing a web service response for jQuery

Question

I'm attempting to gzip a JSON response from an ASMX web service to be consumed on the client-side by jQuery.

My web.config already has httpCompression set like so: (I'm using IIS 7)

<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" 
    staticCompressionDisableCpuUsage="90" staticCompressionEnableCpuUsage="60" 
    dynamicCompressionDisableCpuUsage="80" dynamicCompressionEnableCpuUsage="50">
    <dynamicTypes>
        <add mimeType="application/javascript" enabled="true"/>
        <add mimeType="application/x-javascript" enabled="true"/>
        <add mimeType="text/css" enabled="true"/>
        <add mimeType="video/x-flv" enabled="true"/>
        <add mimeType="application/x-shockwave-flash" enabled="true"/>
        <add mimeType="text/javascript" enabled="true"/>
        <add mimeType="text/*" enabled="true"/>
        <add mimeType="application/json; charset=utf-8" enabled="true"/>
    </dynamicTypes>
    <staticTypes>
        <add mimeType="application/javascript" enabled="true"/>
        <add mimeType="application/x-javascript" enabled="true"/>
        <add mimeType="text/css" enabled="true"/>
        <add mimeType="video/x-flv" enabled="true"/>
        <add mimeType="application/x-shockwave-flash" enabled="true"/>
        <add mimeType="text/javascript" enabled="true"/>
        <add mimeType="text/*" enabled="true"/>
    </staticTypes>
    <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll"/>
</httpCompression>
<urlCompression doDynamicCompression="true" doStaticCompression="true"/>

Through fiddler I can see that normal aspx and other compressions work fine. However, the jQuery ajax request and response work as they should, only nothing gets compressed.

What am I missing?

Answer 1

You can change httpCompression only in applicationHost.config. See this link

Like you, I tried changing it in web.config first, but it didn't work. It worked only when I added the following lines to C:\Windows\System32\inetsrv\config\applicationHost.config:

  <dynamicTypes>
       ...
       <add mimeType="application/json" enabled="true" />
       <add mimeType="application/json; charset=utf-8" enabled="true" />
       ...
  </dynamicTypes>

Answer 2

DO USE NOTEPAD to edit applicationHost.config. I've wasted several hours before understood that my changes made in notepad++ (as well as in Visual Studio 2010 editor!!) aren't applied by IIS.

Alternative way to add additional mimeType into dynamicTypes/staticTypes collection is to use appcmd. "C:\Windows\System32\Inetsrv\Appcmd.exe" set config -section:system.webServer/httpCompression /+"dynamicTypes.[mimeType='application/javascript',enabled='True']" /commit:apphost

And again: after these changes made - you'll see them only in notepad. Notepad++ (as well as Visual Studio 2010 editor!!) maintains some kind of f*ing alternate reality/storage for applicationHost.config. It shows you his own version of the file (different from the one you see in notepad) even after the file edited in notepad and reopened in np++/VS.