[[rcs/git]] and other distributed version control systems are all about
making it easy to create and maintain copies and branches of a project. And
this can be used for all sorts of interesting stuff. Since ikiwiki can use
git, let's explore some possibilities for distributed wikis.

## a wiki mirror

The simplest possibility is setting up a mirror. If a wiki exposes its git
repository and has the [[plugins/pinger]] plugin enabled, then anyone can
set up a mirror that will automatically be kept up-to-date with the origin
wiki. Just clone the git repo, configure ikiwiki to use it, enable the
[[plugins/pingee]] plugin in your configuration, and edit the origin wiki,
adding a ping directive for your mirror:

	\[[!ping from="http://thewiki.com/"
	to="http://mymirror.com/ikiwiki.cgi?do=ping"]]

The "from" parameter needs to be the url to the origin wiki. The "to" parameter
is the url to ping on your mirror.

Now whenever the main wiki is edited, it will ping your mirror, which will
pull the changes from "origin" using git, and update itself. It could, in
turn ping another mirror, etc.

And if someone edits a page on your mirror, it will "git push origin",
committing the changes back to the origin git repository, and updating the
origin mirror. Assuming you can push to that git repository. If you can't,
and you want a mirror, and not a branch, you should disable web edits on
your mirror. (You could also point the cgiurl for your mirror at the origin
wiki.)

## branching a wiki

It follows that setting up a branch of a wiki is just like a mirror, except
we don't want it to push changes back to the origin. The easy way to
accomplish this is to clone the origin git repository using a readonly
protocol (ie, "git://"). Then you can't push to it.

If a page on your branch is modified and other modifications are made to
the same page in the origin, a conflict might occur when that change is
pulled in. How well will this be dealt with and how to resolve it? I think
that the conflict markers will just appear on the page as it's rendered in
the wiki, and if you could even resolve the conflict using the web
interface. Not 100% sure as I've not gotten into this situation yet.

--[[Joey]]
