How do I see if IIS Compression is working using Fiddler? I have a page that, when viewed through Port80Software or GID Network's tool it appears to be coming across compressed.
However, when I watch the call in Fiddler, I see the 'Accept-Encoding: gzip, deflate' in the request header, but I don't see the 'Content-Encoding: gzip' or 'deflate' in the response header. Also, in the Transformer section, 'No Compression' is selected.
Thanks!
Chris
From the Inspectors tab, there is a group of sub -tabs. Make sure you have Transformer selected. Then for each request on the page load, look to see if it was sent with GZIP or No Compression.
Fiddler is pretty good and allows you to pick each individual request made when loading the file.
Based on the various answers and comments, I'm going to conclude that perhaps the page itself (text/html) is compressed, but the text/xml you deliver as part of an AJAX request(?) and the other content delivered for the page is not.
As I already mentioned in a comment, you typically want to compress text/* (i.e. - text/html, text/plain, text/css, etc) and application/javascript & application/ecmascript (as per rfc4329). If you deliver your .js files using some other MIME type (for example, application/x-javascript or text/javascript), compress that instead, or change the MIME type used to deliver .js files to the RFC standard.
See the appropriate link below for updating the MIME types being compressed on your server:
One last point I should make, some web browsers (in particular certain versions of Netscape 4 but there may be others) send Accept-Encoding: gzip,deflate for CSS and JavaScript file requests, but could not actually decompress the content. Also, some versions of Internet Explorer (5.5 & 6) had problems with compression.
I know the default Apache compression configuration I used deals with these issues, I'm not sure how (or whether) IIS compensates for them.
I went straight to the source (to Eric Lawrence) and this is what he said:
Indeed, Fiddler shows your site is compressing properly.
Do you have an upstream proxy server in your environment? Did you try this test from your home network rather than your corporate network?
On Microsoft’s corporate network, we are all behind an ISA proxy server. It’s configured to remove the outbound Accept-Encoding header (which tells servers to use compression) and if a compressed response is received by the proxy, it’s decompressed by the ISA server. This is done so the ISA proxy server can scan the content for malicious data. The downside is that Fiddler is only seeing the traffic as it’s received from the upstream proxy.
Usually, when we need to test compression and the like, we do so from home or what’s called a “DTAP”—a direct line to the internet that doesn’t go through the proxy.
My version of fiddler has and AutoDecode button that made everything appear to have No Compression. After turning this off, my responses showed compression