ikiwiki/doc/features.mdwn

An overview of some of ikiwiki's features:
[[toc ]]

## Uses a real RCS

Rather than implement its own system for storing page histories etc,
ikiwiki uses a real Revision Control System. This isn't (just) because we're
lazy, it's because a real RCS is a good thing to have, and there are
advantages to using one that are not possible with a standard wiki.

Instead of editing pages in a stupid web form, you can use vim and commit
changes via [[Subversion]]. Or work disconnected using svk and push your
changes out when you come online. Or use [[git]], [[tla]], or [[mercurial]]
to work in a distributed fashion all the time. (It's also possible to
[[plugins/write]] a plugin to support other systems.)

ikiwiki can be run from a [[post-commit]] hook to update your wiki
immediately whenever you commit a change using the RCS.

Note that ikiwiki does not require a RCS to function. If you want to
run a simple wiki without page history, it can do that too.

## A wiki compiler

ikiwiki is a wiki compiler; it builds a static website for your wiki, and
updates it as pages are edited. It is fast and smart about updating a wiki,
it only builds pages that have changed (and tracks things like creation of
new pages and links that can indirectly cause a page to need a rebuild)

## Supports many markup languages

By default, pages in the wiki are written using the [[MarkDown]] format.
Any page with a filename ending in ".mdwn" is converted from markdown to html
by ikiwiki. Markdown understands text formatted as it would be in an email,
and is quite smart about converting it to html. The only additional markup
provided by ikiwiki on top of regular markdown is the [[WikiLink]] and 
[[PreprocessorDirective]].

If you prefer to use some other markup language, ikiwiki allows others to
easily be added by [[plugins]]. For example it also supports traditional
[[plugins/WikiText]] formatted pages, pages written as pure
[[plugins/HTML]], or pages written in [[reStructuredText|plugins/rst]]
or [[Textile|plugins/textile]].

ikiwiki also supports files of any other type, including plain text,
images, etc. These are not converted to wiki pages, they are just copied
unchanged by ikiwiki as it builds your wiki. So you can check in an image,
program, or other special file and link to it from your wiki pages.

## [[Blogging|blog]]

You can turn any page in the wiki into a [[blog]]. Pages matching a
specified [[PageSpec]] will be displayed as a weblog within the blog
page. And RSS or Atom feeds can be generated to follow the blog.

Ikiwiki's own [[TODO]], [[news]], and [[plugins]] pages are good examples
of some of the flexible ways that this can be used. There is also an 
[[example_blog|examples/blog]] set up that you can copy into your own wiki.

Ikiwiki can also [[plugins/aggregate]] external blogs, feeding them into
the wiki. This can be used to create a Planet type site that aggregates
interesting feeds.

You can also mix blogging with podcasting by dropping audio files where
they will be picked up like blog posts. This will work for any files that
you would care to syndicate.

## Valid html and [[css]]

ikiwiki aims to produce 
[valid XHTML 1.0](http://validator.w3.org/check?url=referer). ikiwiki
generates html using [[templates|wikitemplates]], and uses [[css]], so you
can change the look and layout of all pages in any way you would like.

## [[Plugins]]

Plugins can be used to add additional features to ikiwiki. The interface
is quite flexible, allowing plugins to implement additional markup
languages, register [[PreProcessorDirective]]s, hook into [[CGI]] mode,
and more. Most of ikiwiki's features are actually provided by plugins.
Ikiwiki's backend RCS support is also pluggable, so support for new
revision control systems can be added to ikiwiki.

The standard language for ikiwiki plugins is perl, but ikiwiki also supports
[[plugins/write/external]] plugins: Standalone programs that can be written in
any language and communicate with ikiwiki using XML RPC.

## [[todo/utf8]]

After rather a lot of fiddling, we think that ikiwiki correctly and fully
supports utf8 everywhere.

## Other features

The above are the core design goals and features of ikiwiki, but on that
foundation a lot of other important features are added. Here is an
incomplete list of some of them.

### [[Tags]]

You can tag pages and use these tags in various ways. Tags will show
up in the ways you'd expect, like at the bottom of pages, in blogs, and
in RSS and Atom feeds.

### [[SubPages|SubPage]]

Arbitrarily deep hierarchies of pages with fairly simple and useful
[[SubPage/LinkingRules]]

### [[BackLinks]]

Automatically included on pages. Rather faster than eg MoinMoin and
always there to help with navigation.

### Smart merging and conflict resolution in your web browser

Since it uses a real RCS, ikiwiki takes advantage of its smart merging to
avoid any conflicts when two people edit different parts of the same page
at the same time. No annoying warnings about other editors, or locking,
etc, instead the other person's changes will be automatically merged with
yours when you commit.

In the rare cases where automatic merging fails due to the same part of a
page being concurrently edited, regular commit conflict markers are
shown in the file to resolve the conflict, so if you're already familiar
with that there's no new commit marker syntax to learn.

### [[RecentChanges]], editing pages in a web browser

Nearly the definition of a wiki, although perhaps ikiwiki challenges how
much of that web gunk a wiki really needs. These features are optional
and can be enabled by enabling [[CGI]].

### User registration

Can optionally be configured to allow only registered users to edit
pages.

User registration can be done using a web form, or ikiwiki can be
configured to accept users authenticated with OpenID, or HTTP basic
authentication, or other methods implemented via plugins.

### Discussion pages

Thanks to subpages, every page can easily and automatically have a
/Discussion subpage. By default, these links are included in the
[[templates]] for each page.

### Edit controls

Wiki admins can [[lock_pages|page_locking]] so that only other admins can
edit them. Or a wiki can be set up to allow anyone to edit Discussion
pages, but only registered users to edit other pages. These are just two
possibilities, since page edit controls can be changed via plugins.

### [[PageHistory]]

Well, sorta. Rather than implementing YA history browser, it can link to
[[ViewVC]] or the like to browse the history of a wiki page.

### Full text search

ikiwiki can use the [[HyperEstraier]] search engine to add powerful
full text search capabilities to your wiki.

### Commit mails

ikiwiki can be configured to send you commit mails with diffs of changes
to selected pages.

### [[w3mmode]]

Can be set up so that w3m can be used to browse a wiki and edit pages
without using a web server.