Where is global Rails configuration?

Hi,

Let's say I wanted to add something to Rails that I would like all
applications to use. For example, I would like to add the pluggable
parameter parsing using:

ActionController::Base.param_parsers['application/atom+xml'] =
Proc.new do |data|
  node = REXML::Document.new data
  { node.root.name => node.root }
end

(got this example from e.g. http://www.linuxjournal.com/article/8968,
but it's also in the source code). I would not like this to be related
to a specific controller or application - I would like to add it for
all applications at once. In this case, it would be for both already
existing applications and the ones I create. What is the appropriate
place for this (if any)? I know that editing environment.rb is a good
place for per-application settings.

Yes, another (relatively simple) way would be to just 'require' the
Ruby file with these settings in all applicaitons, but I am just
curious if there is some standard way of doing this.

I would say the appropriate place for this would be in a plugin.
Doing anything else would mean modifying the Rails core code, which
I'm guessing would violate your Rails open source license agreement
(unless you're a Rails contributor). Basically, if you modify Rails
it won't be Rails anymore.

Rails is kind enough to offer a plug-in architecture where you should
be able to do what you want and include it into all or your
applications.