Version Control with SVN

Version Control with SVNby Michelangelo van Dam

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PHPBelgium meeting 22/10/2008Cafe Sport Leuven

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About me

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Michelangelo van Dam

Enterprise PHP ConsultantZend Certified EngineerCo-founder PHPBelgiumContributor Zend FrameworkPHP Advocate

E-mail: dragonbe@gmail.comBlog: http://dragonbe.comTwitter: http://twitter.com/DragonBe

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About this presentation

• Concepts of version control• Management with subversion• Life cycle of a project in subversion• Parts and structures within subversion• Advanced subversion tools• New in release 1.5

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What is version control ?

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“Revision control (also known as version control ...) is the management of multiple revisions of the same unit of information.”(source: Wikipedia:RevisionControl)

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Version Control for PHP devs...

• version control provides–management of versions of information

•code/tests• configuration files•documentation

– in a structured, standardized way–with repositories

• centralized (SVN, CVS)•decentralized (GIT)

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Why need version control ?

• enables collaboration between developers• centralized “main code” (trunk)• custom code alongside main code (branching)• eases release management (tags)• rollback to previous revisions• integration with other tools

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Subversion (SVN)

• Subversion (http://subversion.tigris.org)• more advanced than CVS• less complex than GIT• integrates well with other tools

(trac, gforge, jira, ...)• supported by many tools

(Zend Studio, TurtoiseSVN, Subversion CLI)

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An example project in trac

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SVN browser in Zend Studio

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Code management with SVN

• many developers create much code• code is committed to a central repository

–conflicts trigger warnings

• user and groups can be defined• different versions can co-exist• access management for named and

anonymous access rights

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Subversion authentication

• svnserve daemon$ svn svn://server/project/trunk

• svnserve daemon over SSH$ svn svn+ssh://server/project/trunk

• Apache webserverhttp://svn.server/project/trunk

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Version management

• all code resides in “trunk”• code version are detached in “branches”• snapshots for releases are “tagged”

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Release management

• a release is a snapshot of a version branch• are being deployed to server environments• for live or production environments

don’t check out in document root !–use release folders svn co svn://server/myproj/tags/rel-1.0 /web/myproj-rel-1.0

–create symlink to itln -s /web/myproj-rel-1.0 /web/myproj

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SVN life cycle

v1.0 v1.1

rel-1.1.1 rel-1.1.2

rel-1.0.1 rel-1.0.2

custom dev branch

bug fixTrunk

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Trunk

• trunk is where all code resides–except custom development

• has always the latest version• is not always the most stable version

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Branch

• two kind of branches exists–custom development branches–version branches

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Custom development

• code that changes many things in trunk• are best put in a separate branch• maintained by their developer(s)• and merged back into trunk

–after the merge, the branch is removed

• when changes are done and tested

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Versions

• are maintained in branches• have a long lifetime cycle (several years)• differ from each other

–because of new code base, framework, language

• have a common base = trunk• fixes from versions go into trunk• back port fixes go from trunk into version

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Tags

• tags are snapshots• usually made on version branches• can also be made on “trunk”• are deployed (exported) to staging

environments• are used to keep track what’s happened

between releases (change log)

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More than just version control

• Subversion provides more features–File portability–Keyword substitution–Locking–Externals–Peg and Operative revisions–Network model–Hooks

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File portability

• Line endings differ on different OSses–are ignored when checking modifications

• Mime-types differ from their extensions–binary and non-binary files are tested on content

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Keyword substitution

• Only a few keywords are substitute–$Date:$ › $Date: 2008-10-22 20:00:00 +0100 (Wed,

22 Oct 2008) $–$Revision:$ › $Revision: 144 $–$Author:$ › $Author: svnusername $–$HeadUrl:$ › $HeadUrl: http://svn.test.be/trunk $–$Id:$ › $Id: file.php 148 2008-10-22 20:00:00Z

svnusername $

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Locking

• working copy locks–exclusive right to a working copy–clears with “svn cleanup”

• database locks–ensures database integrity–only admins can remove this lock

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Externals

• Externals provide an easy way to–include other internal or external projects–without having to care about there revisions

• Examples:–Zend Framework as svn:externals on library path–project that includes many smaller projects

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Peg and Operative revisions

• automated handling of–moving files–deleting and creating new files with same name

• Using specific syntax–$ svn command -r OPERATIVE-REV item@PEG-REV

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Network model

• Can run it’s own svnserve–pros: no dependencies, works with ssh for extra

security–contras: need svnclient to connect

• Or in combination with Apache webserver–pros: works with any http-client–contras: overkill for small projects, requires

mod_dav_svn, more difficult to set up

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Hooks

• Hooks facilitate actions to be taken–before a commit starts (validate rights)–after a commit (send e-mail, update tracker, ...)–before or after a revision change (notifications)

• Can easily be incorporated with tools–tracking tools– integration tools (Lorna Jane’s Nabaztag)–mailing and logging systems

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Hooks execute moments

• basic commit moments:–start-commit:

• runs before commit transaction started

–pre-commit:• runs right before commit transaction is promoted

–post-commit:• runs after the commit transaction is finished

–...

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Cool things with SVN hooks

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Lorna Jane’s Nabaztag

Responding on SVN commits

http://www.flickr.com/photos/lornajane/2592602734/

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New features in Subversion v1.5

• Merge tracking (foundational)• Sparse checkouts (via new --depth option)• Interactive conflict resolution• Changelist support• Relative URLs, peg revisions in svn:externals• Cyrus SASL support for ra_svn and svnserve• ... (more on http://subversion.tigris.org/

svn_1.5_releasenotes.html)

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Summary

• manageable file change history• better collaboration between developers• clearer release management• more then one version of same code base• easier to rollback in case of emergency

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Thank you...

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Questions ?Michelangelo van Dam - dragonbe@gmail.comhttp://slideshare.net/PHPBelgium/version-control-with-svn-presentation

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