15.2. Obtaining Subversion

The Subversion project web site is http://subversion.tigris.org/. It contains links to project documentation, Frequently Asked Questions (FAQs), and project source code.

Some GNU/Linux systems come with Subversion available on the installation CDs. Thus, you may be able to install a pre-built binary for your system, or use a package manager to download and install it.

15.2.1. Subversion Releases

Subversion uses the "even/odd" release model. Even numbered point releases (1.0, 1.2, etc.) are considered to be stable releases. Such releases undergo change only to fix problems. New features are not added, and users can expect to use the software without problems. Odd numbered point releases (1.1, 1.3, etc.), on the other hand, are development versions. New features are added in such versions, they tend to undergo rapid change and evolution, and such releases may have bugs or problems that could cause loss of data. You should use an even-numbered release if stability and data preservation are important to you. Use an odd-numbered release only if it has a critical, must-have feature and if you are willing to live with the risks involved.

15.2.2. A View Down the Road

The one constant in the Open Source world is change. At the time of writing, Subversion 1.0 is the current released stable version. The first development release of Subversion 1.1 is also available. Along with a host of fixes and several new command-line options, the next version has the following interesting features:

Symbolic links may be versioned

Unix-style symbolic links are stored in the repository as a regular file with a special attribute. The svn client knows how to store and extract symbolic links correctly on Unix-style systems.

Nondatabase repository back-end

Repositories can be set up to store data in regular files, instead of requiring the use of Berkeley DB.

Better localization support

The framework for localization of the Subversion code has been improved, with at least eight translations already available.

The Subversion web site's Roadmap page (http://subversion.tigris.org/roadmap.html ) lists the following future development goals (you should recheck the web site; things will undoubtedly have changed):

Subversion 1.2 goals

• Optional locking (reserved checkouts)

Medium-term goals

• True rename support (not based on copy/delete)

• Merge tracking (describes a whole class of problems)

• Repository-level Access Control Lists (ACLs)^[*]

  ^[*] ACLs provide finer-grained access controls than the regular Unix user/group/other permissions mechanism. Many Unix systems support some form of ACLs, but in incompatible ways.

Long-term goals

• SQL repository back-end

• Rewrite of working-copy library

• Broader WebDAV/deltaV compatibility^[]

  ] WebDAV is short for "Web-based Distributed Authoring and Versioning," an extension to HTTP that makes read/write file resources available over the Web. Despite the "V in the name, the original specification (RFC 2518) does not provide a model for version control; this is provided by DeltaV, described in RFC 3253. See http://www.webdav.org for more information.

• Pluggable client-side diff programs

• Progressive multilingual support

15.2.3. Source Code

The latest Subversion source is kept in a Subversion archive available from the main Subversion site. This leads to a so-called bootstrapping problem; you can't get Subversion unless you already have it. Fortunately, the developers make Subversion releases available as standalone tar archives that you can use to build your initial Subversion client. You can get these from the main web site, http://subversion.tigris.org. Once there, select the "Downloads" link. You may choose to download a binary distribution (Red Hat RPM file, Debian package, etc.), if one is available. This is the easiest road to take. Or you may choose to download source code and build your own. Building Subversion follows the general steps outlined in the section "Building Software," in Chapter 1.