de-centralised version control with bazaar

Bazaar Version ControlStuart Colville and Andrew Phillipo

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 baseX

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 - SubversionProject 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 BazaarEasy 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/