De-centralised Version Control with Bazaar

Bazaar Version Control Stuart Colville and Andrew Phillipo

X Version Control Software A way to keep a multiple revisions of a single resource without creating copies Undo either short or long term Audit-trail of who did what and when Access to details of why a change was made Tools to help teams of developers work on a single code base

History of Version Control Systems “Those who cannot remember the past are condemned to repeat it.” - George Santanya

SCCS - Source Code Control System The ﬁrst Version Control System, built during the 70s Was dominant until RCS was released SCCS had no concept of branching Internal ﬁle format is still used today by Bitkeeper and TeamWare Tools still available to access the SCCS format

RCS - Revision Control System Built During the 80s as “a better SCCS” Only knows about revisions of single ﬁles Supports branching, badly “RCS automates the storing, retrieval, logging, identiﬁcation, and merging of revisions.” - GNU RCS homepage

CVS - Concurrent Versioning System Originally based upon RCS (for managing sets of ﬁles/projects) in the late 80s, by Dick Grune and later rewritten by Brian Berliner Only ﬁles are versioned, no symlinks or directories No direct moving/renaming capability Branching and merging can be a world of pain Allows control over who can commit Stable, well supported infrastructure and tools

HTTP://FLICKR.COM/PHOTOS/EECUE/91518838/

SVN - Subversion Project start by collab.net in 2000 Built to improve on CVS Atomic commits Allows renaming/moving of assets Language bindings for all common programming languages

What do you look for in a revision control system? Stability Easy to use Doesn’t get in the way of me developing my stuff Flexibility Extensible

Introduction to Bazaar Easy to branch and smarter merging First-class renaming capabilities No server software needed - “Batteries included” Designed with usability, ease of use in mind Cross platform: Linux, BSD, OSX, Windows Flexible and extensible, with a full plug-in system

BAZAAR DOESN’T GET IN THE WAY

Bazaar Workﬂows

Workﬂows: Solo As simple as pick a directory and tell bazaar to start versioning it No server/database setup Sharing with other developers is easy, should it be needed Let’s look at an example...

Set-up a versioned dir $ cd ~/bazaar/demo $ bzr init ~/bazaar/demo is now set-up to be versioned

Let’s add a ﬁle $ vim test.css $ bzr add

Let’s add a ﬁle $ vim test.css $ bzr add added test.css

First commit $ bzr commit -m “my first commit”

First commit $ bzr commit -m “my first commit” added test.css Committed revision 1.

Workﬂows: Partner

Workﬂows: Centralised

Workﬂows: Local Commit

Workﬂows: Shared

Workﬂows: Gatekeeper

Workﬂows: PQM

Why use Distributed VCS in tandem with Centralised Version Control? Company policy requires the use of a centralised system Development with centralised VCS is harder A modern VCS brings more advanced merging Reduction in developer suicide rate

Using Distributed VCS in tandem with Centralised Version Control Keeping history: Tailor is a tool that can convert between many different rcs http://progetti.arstecnica.it/tailor CVSPSImport converts directly from CVS http://bazaar-vcs.org/CVSPSImport Ignore history and take current set of ﬁles Faster but obviously you lose access to older history

Launchpad.net Similar to sourceforge with 100% less CVS Tightly integrated with Bazaar - though import from other VCS is possible Removes the barriers to contributing open- source development Bug tracking, FAQ, Documentation and translation management

Launchpad Example Bazaar-email is a simple plug-in that uses the post-commit hooks in bazaar to mail diffs To contribute back to the project I raised bugs for trivial issues found using the plug-in A developer ﬁxed one of these issues and submitted a branch linked to the bug To add this to trunk the maintainer can simply carry out a merge

Launchpad Bug fix process Branch the trunk/main branch Make + test the fix Push the fix back to launchpad and associate it with the bug number bzr push sftp://user@bazaar.launchpad.net/~user/project/branch The maintainer can then merge the fix into the trunk

Adding a feature to a project Branch the trunk/main branch Merged pending bugﬁxes Develop the feature Push to launchpad bzr push sftp://user@bazaar.launchpad.net/~user/project/branch Raise merge request

Let’s hack on something

Conclusion Version control has come a long way De-centralisation is the future! First-class merging makes this all possible Development should never be constrained by the version control system you use

Questions? That’s all folks! http://bazaar-vcs.org/

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De-centralised Version Control with Bazaar

by Stuart Colville on Dec 09, 2007

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De-centralised Version Control with Bazaar — Presentation Transcript