Version Control Systems: Svk

Forest Bond

Overview

Author:

Chia-liang Kao

Model:

distributed, but designed to work with a central server

Language:

Perl

License:

Perl (Artistic & GPL)

History

• Svk was originally written by Chia-liang Kao, and was initially released as version 0.01 on November 19th, 2003.
• Chia-liang has since joined Best Practical, makers of the somewhat-well-known ticketing system RT (Request Tracker). Svk is now a Best Practical product (which means they provide commercial support for it).
• Current version of Svk is 1.0.8. Svk is used by many projects, including:
  • KDE
  • WINE
  • Ruby on Rails

Concept

Svk is a distributed system, but is designed to be used as an extension to a centralized system. In other words, Svk has the concept of "upstream" built in.

• This arrangement encourages a workflow that pushes and pulls changesets to and from a centralized repository.
• Local, non-public branches can still be created at will, allowing for unfettered code experimentation with all of the benefits of off-line changeset management.
• Effectively, you get svn with a local repository that easily syncs with the centralized server.

Concept (cont'd)

Svk (like Subversion), takes a generic approach to repository contents:

• A single local repository (the "depot") stores an arbitrary directory structure.
• Each directory in the depot may or may not be associated with an upstream repository; those that are can be periodically sync'ed.
• Changes can be pushed and pulled to and from the parent of the directory being worked in (which may be a mirror of a remote repository location or just another branch in the local depot).

Concept (cont'd)

Typical depot structure:

• /
  • mirror
    • myproject
  • local
    • myproject
    • myproject_experimental_branch
    • myproject_other_experimental_branch

User Interface

The primary Svk interface is the svk command-line utility:

• The svk command-line interface should be familiar to Subversion/CVS users.
• In addition to the standard svn commands, svk also provides some commands for utilizing its distributed features: mirror, sync, push, pull.
• svk has smerge ("star merge"); you don't have to remember revision numbers to merge.

Advantages & Disadvantages

Advantages:

• Cross-platform
• Built on proven technology
• Integrates with widely used centralized systems
• Has smerge :)

Disadvantages:

• Limited merge freedom (No cherry-picking)
• No unique identification of file objects or changesets — how robust can smerge be?
• Written In Perl :)

Advantages – Cross-Platform

Svk should run on any system with a reasonably complete Perl implementation. This includes:

• GNU/Linux
• Mac OS X
• FreeBSD
• NetBSD
• Solaris
• Windows

Advantages – Integration With Centralized Systems

Svk current supports mirroring of centralized repositories managed using the following packages:

• Subversion
• Perforce
• CVS

Conclusion

Svk is a de-centralized VCS that you can actually use at work, and enables efficient branch-merge style workflows even without a network connection.