Source ControlLandscape

Lorna Jane Mitchell

PHP London, October 2010

About Me

Lorna Jane Mitchell Freelance PHP consultant/developer/trainer Speaker and Writer Based in Leeds, UK (in town for FOWA) Homepage: http://lornajane.net Twitter: @lornajane

Source Control

Tool History Subversion The future: DVCS

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Subversion (svn)

Creator CollabNet

URL http://subversion.apache.org

Maintainer Apache

Users PHPSourceforgeFreeBSDApache Software Foundation

License Apache/BSD style

Documentation Excellent, more matureRed Bean Book

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Subversion: The Roapmap Taken from:

● http://lwn.net/Articles/381794/

Subversion exists to be universally recognized and adopted as an open-source, centralized version control system characterized by its reliability as a safe haven

for valuable data; the simplicity of its model and usage; and its ability to support the needs of a wide

variety of users and projects, from individuals to large-scale enterprise operations.

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Git

Creator Linus Torvalds

URL http://git-scm.com/

Maintainer Junio Hamano

Users Linux kernelRuby on RailsCakePHPDebianGNOME

License GPL

Documentation "terse", a lot of documentation for an unfamiliar system

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Bazaar (bzr)

Creator Martin Pool

URL http://bazaar.canonical.com/

Maintainer Canonical

Users UbuntuMySQLInkscapeSquid

License GPL

Documentation Excellent! Aimed at beginners, UI designed to be intuitive

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Mercurial (hg)

Creator Matt Mackall

URL http://mercurial.selenic.com/

Maintainer Matt Mackall

Users MozillaOpenOffice.orgSymbianOSNetBeans

License GPL

Documentation Good, online book and command line help

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Features Atomic commits File renames Symbolic links Pre/Post event hooks Merge tracking Tags EOL conversions

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Protocols Everything supports SSH and HTTP(S) Distributed systems support email Bazaar supports FTP Git supports rsync

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Centralised vs Distributed Source Control

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Centralised Source Control Traditional model Subversion uses this Other products can do it

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Centralised Source Control

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Distributed Source Control

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Distributed Source Control Same function as centralised source control Very different approach Steeper learning curve Key concepts

● local repositories● revisions● branching

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Local Repository

Clone a whole repo It's FAST Can commit without sharing Can rewrite history

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Snapshots vs Changesets From a Joel Spolsky post:

With distributed version control, the distributed part is actually not the most interesting part.

The interesting part is that these systems think in terms of changes, not in terms of versions

Snapshots vs Changesets

Subversion commit is a snapshot of the codebase

For a DCVS, it's a set of changes Makes it easier to share changes Can be applied in different orders Cherry-picking

Branching

Branches in DCVS are not just copies Working copy can switch between them Private branching

The Social Aspect

Hosted Code Solutions

Combat the complexity of DCVS Supporting tools e.g. GitHub

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Code Hosting and Collaboration Provide repository space Repo browsing, linked projects Forums and mailing lists Wiki (or similar: launchpad has blueprints) Publish downloadable versions Message other collaborators

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Code Hosting Providers

GitHubhttp://github.com/

git

Bitbuckethttp://bitbucket.org/

hg

Google Codehttp://code.google.com/

svn, hg

Launchpadhttps://launchpad.net/

bzr

SourceForgehttp://sourceforge.net/

svn, bzr, hg, git (and cvs)

Tools and Choices

Trac

Trac supports all mentioned products Code browsing Commit messages update issues

GUI Tools

Moving target! Improving IDE support Tortoise* products Limited support for git on windows

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Building Bridges Bridge between SVN repo and local

● bzr-svn https://launchpad.net/bzr-svn

● git-svn http://www.kernel.org/pub/software/scm/git/docs/git-svn.html

Local distributed-style repo Communicates with central SVN server Pulls complete history

● diff, log fast and offline

Work offline, commit later

Access Control

SVN has granular access control Can use various apache mechanisms Control access by path DCVS are much newer, access control uses

hooks Can control writes What about reads?

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Cost of Transition Steeper learning curve Implementation costs

● tool migration● process changes● supporting tool migration● user training (ongoing!)

Hype and dismissive attitudes are unhelpful

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Making Choices Global team of expert geeks - use DCVS (any

one) Colocated team of mixed ability - use SVN Everything else is a sliding scale! Consider

● Your people● Your admins● The documentation, support and community of your

chosen solution

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Any Questions?

Thanks!

@lornajane

http://lornajane.net