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Katie

Michael Davies writes

Another SCM you could consider / promote is "Katie" written by Geoffrey Bennett. Despite saying pre-release on the web site, it self hosts, and works pretty well (as a Rational ClearCase equivalent).

I have to admit that I think doing software version control in the filesystem is fundamentally wrong. A filesystem that keeps backups or snapshots is cool. Doing things in the filesystem is always going to be harder to install and more prone to nasty failure than a simple userspace application. (I understand Katie is actually a Perl userspace NFS server, which is pretty cool, and much cleaner than putting it in the kernel.)

But several people seem to like Katie, so I suppose I should try it sometime. If you've tried it and like it, why not write and tell me what you think?

Geoffrey says the main features are:

• The equivalent of 'cvs checkout' is nearly instantaneous as there is no need to download any files.

• Access to previous versions of files can be done through the filesystem using standard Unix commands. For example, rather than:
  cvs diff -r1.1 -r1.2 myfile
  you can do:
  diff myfile@@/main/[12]
  

  or:
  diff myfile@@/main/3 myfile@@/main/LATEST
  ('myfile@@' is a hidden directory containing the entire revision history of 'myfile').

Arch can do something called a "revision library", which is directory tree of selected previous revisions. Identical files are hardlinked together, so it can be quite compact. When you get a new checkout, you can use the --links option to build hard links into the revision library, if you know that your editor correctly breaks hardlinks.

So it approachs the method some kernel developers use, of having many working trees created with cp -al, but it's more systematic.

This makes it pretty easy to use any tools on the trees. For example you can run dirdiff to compare your current tree to any previous revision. Because diff understands hardlinks, comparisons are very quick.

posted Mon 16 Feb 2004 in /software/vc/katie | link

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