The first edition of this book was released in 2004, shortly after Subversion had reached 1.0. Over the following four years, Subversion released five major new versions, fixing bugs and adding major new features. While we’ve managed to keep the online version of this book up to date, we’re thrilled that the second edition from O’Reilly now covers Subversion up through release 1.5, a major milestone for the project. Here’s a quick summary of major new changes since Subversion 1.0. Note that this is not a complete list; for full details, please visit Subversion’s web site at http://subversion.tigris.org.
Release 1.1 introduced FSFS, a flat-file repository storage option for the repository. While the Berkeley DB backend is still widely used and supported, FSFS has since become the default choice for newly created repositories due to its low barrier to entry and minimal maintenance requirements. Also in this release came the ability to put symbolic links under version control, auto-escaping of URLs, and a localized user interface.
Release 1.2 introduced the ability to create server-side locks on files, thus serializing commit access to certain resources. Although Subversion is still a fundamentally concurrent version control system, certain types of binary files (e.g., art assets) cannot be merged together. The locking feature fulfills the need to version and protect such resources. With locking also came a complete WebDAV autoversioning implementation, allowing Subversion repositories to be mounted as network folders. Finally, Subversion 1.2 began using a new, faster binary-differencing algorithm to compress and retrieve old versions of files.
Release 1.3 brought path-based authorization controls to the svnserve server, matching a feature formerly found only in the Apache server. The Apache server, however, gained some new logging features of its own, and Subversion’s API bindings to other languages also made great leaps forward.
Release 1.4 introduced a whole new tool—svnsync—for doing one-way repository replication over a network. Major parts of the working copy metadata were revamped to no longer use XML (resulting in client-side speed gains), while the Berkeley DB repository backend gained the ability to automatically recover itself after a server crash.
Release 1.5 took much longer to finish than prior releases, but the headliner feature was gigantic: semiautomated tracking of branching and merging. This was a huge boon for users, and it pushed Subversion far beyond the abilities of CVS and into the ranks of commercial competitors such as Perforce and ClearCase. Subversion 1.5 also introduced a bevy of other user-focused features, such as interactive resolution of file conflicts, partial checkouts, client-side management of changelists, powerful new syntax for externals definitions, and Simple Authentication and Security Layer (SASL) authentication support for the svnserve server.