Configuring HTTP Compression

When compression is enabled in the server, an entry gets added to the obj.conf file. A sample entry is shown below:

Output fn="insert-filter" filter="http-compression" type="text/*"

Depending on the options specified, this line might also contain these options:

vary="on" compression-level="9"

To restrict compression to documents of only a particular type, or to exclude browsers that don’t work well with compressed content, you would need to edit the obj.conf file, as discussed below.

The option that appears as:

type="text/*"

restricts compression to documents that have a MIME type of text/* (for example, text/ascii, text/css, text/html, and so on). This can be modified to compress only certain types of documents. If you want to compress only HTML documents, for example, you would change the option to:

type="text/html"

Alternatively, you can specifically exclude browsers that are known to misbehave when they receive compressed content (but still request it anyway) by using the <Client> tag as follows:

<Client match="none"\
browser="*MSIE [1-3]*"\
browser="*MSIE [1-5]*Mac*"\
browser="Mozilla/[1-4]*Nav*">
Output fn="insert-filter" filter="http-compression" type="text/*"
</Client>

This restricts compression to browsers that are not any of the following:

• Internet Explorer for Windows earlier than version 4

• Internet Explorer for Macintosh earlier than version 6

• Netscape Navigator/Communicator earlier than version 6

  Internet Explorer on Windows earlier than version 4 may request compressed data at times, but does not correctly support it. Internet Explorer on Macintosh earlier than version 6 does the same. Netscape Communicator version 4.x requests compression, but only correctly handles compressed HTML. It will not correctly handle linked CSS or JavaScript from the compressed HTML, so administrators often simply prevent their servers from sending any compressed content to that browser (or earlier).

  For more information about the <Client> tag, see the The Client Tag.