What is a good setting for noCompressionUserAgents in Tomcat?

Question

Googling for "noCompressionUserAgents" ends up with the same boilerplate config that seems to have been copied around and yet is not very useful (and even is here on stackoverflow:)

stackoverflow.com/questions/550024/tomcat-compression-does-not-add-a-content-encoding-gzip-in-the-header

noCompressionUserAgents="gozilla, traviata"

But this doesn't take into account skipping NS4 or IE6 or whatever else. The closest I've found is from a Zimbra config sample, which at least is for skipping IE6 it looks like:

http://www.zimbra.com/forums/installation/7654-problems-zimbra-installation-os-x-server-ldap-tomcat.html

noCompressionUserAgents=".MSIE 6."

Does anybody have a REAL setting for noCompressionUserAgents?

Answer 1

In general, the best approach is to manually pick out the ones that break and add them to it. Most agents that do not support gzip will simply not advertise gzip support (and therefore you probably shouldn't try to ignore them and send it anyway).

For example, IE6 does support compression, however there can be quirky interactions with it. These are far from 100% of the cases, though (we use compression with IE6 clients in most cases, with only a few pages excluded due to bugs we found in testing).

The bottom line is that the reason you haven't found a blacklist is likely because there really is no valid one-size-fits-all blacklist available.

Answer 2

If it helps, Apache has a de-facto standard set of directives for disabling compression for certain user agents, which you may be able to convert to tomcat's syntax. These are the recommended settings for Apache, rather than just being examples.