[isabelle-dev] Repository and Wiki [was: push request (Sublist.thy)]

[Makarius]

On Sat, 15 Dec 2012, Florian Haftmann wrote:

> I started this repository for two reasons:
>
> * I had to cleanup the webserver configuration and needed proper 
> versioning.
>
> * I wanted to discover ways to maintain documentation in a lightweigth 
> fashion apt to versioning.

Such a purely administrative repository for internal use does have a 
purpose, since not every aspect of the TUM configuration needs to be made 
world-readable on public servers.

We merely need to learn where to draw the line.  For example, the isatest 
settings have greatly benefitted from being exposed in 
Admin/isatest/settings under official version control.  Before it was 
always a guess in the dark what isatest was using in a failed test in the 
first place.


> Concerning wikis in general, since over one year I do not consider 
> mediawiki the tool of choice for our purpose.  It requires massive 
> infrastructure, its format is a sink (only mediawiki can parse 
> mediawiki), and is hopelessly tied to a RDMS backend which is useless 
> until the number of your users grows beyond, say, 10 in a minute (just 
> to give a figure).

For my part, I knew that already before the start of the community wiki. 
MediaWiki is "the" standard wiki in public perception, mainly because 
Wikipedia uses it.  But Wikipedia uses massive add-on technology and 
social and administrative structures to arrive at its perceived quality. 
Without that a MediaWiki wiki becomes a sink for rubbish by default.


The Isabelle community wiki has emerged in a classic way you normally tell 
first-year students as bad joke in software technology management:

   * 2-3 users (students) had asked for a wiki at TUM for their own use
     as "isanotes".

   * Without spending any time to think about the "implementation" the
     admins were asked to install a mediawiki server that they happened to
     have already running anyway.  It was known to be an insignifant,
     temporary experiment, so nobody cared much.

   * Since the wikiserver happened to be there already, it was re-dedicated
     to host the Isabelle community wiki.

So systematic use of things that just happened to be there by accident. 
This is the standard way to produce a lot of follow-up costs in everyday 
use and maintenance of the result.


> If a wiki frontend seems critical, as of today I would recommend 
> something like Gitit http://gitit.net/, which uses hg or git as backend, 
> with all benefits like easy integration into versioning infrastructure, 
> usable without frontend etc.

This is one of the many starting points for contemporary technology to do 
the job, in a more lightweight and more robust way than old Mediawiki.

Every time I pass by Bitbucket, I am impressed how nice they make a 
secondary "wiki" repository appear on the web, using the existing concepts 
of Mercurial repository + interpretation of Markdown. Even the "main" 
repository looks nice on the web, with rendering of README within each 
directory.  (They even have a tracker that does not look like the first 
big issue to be tracked with it, but it poses probably a vendor-lock-in 
problem, unlike the wiki with its generic hg + md basis.)


 	Makarius