The 1.5 release of Subversion, the open source configuration management system used on software development projects, has been given a stronger "merge" tracking mechanism and leaner code checkouts per developer.

The enhancements make it easier to identify who did what to a section of code, track changes, resolve conflicts between sections of code, and assemble main trunks of distributed projects with many branches.

"The 1.0 version lacked a really good tracking mechanism," noted Victoria Griggs, senior director of marketing. "Now the committers can track where the merges have gone, into a branch or into a code trunk." The 1.5 system produces an annotated log history to record what code was worked on by whom and what changes were made to it.

Subversion automatically checks for conflicts between different code submissions and alerts a project administrator if any are found.

Increasingly, Subversion is used inside the enterprise on internal projects. A survey of Apache Web servers found 300,000 copies of Subversion at work on projects both inside and outside the enterprise. Many instances of Subversion being used inside the enterprise couldn't be counted because the Web crawler can't see behind the enterprise firewall, said Tony de la Lama, strategy director at CollabNet, which started the Subversion project in 2000.

Version 1.0 was released by Subversion developers in February 2004, although the system was already in widespread use in open source projects by then. Subversion competes with Borland StarTeam, IBM Rational ClearCase, Serena Dimensions Express, and ChangeMan ZMF. Telelogic, MKS, and Microsoft also have configuration management products. The Forrester Research Wave report on standalone change management systems concluded in the second quarter of 2007 that Subversion was the market leader.

"Subversion's strengths are scalability, administration, and geographic distribution ... single instances manage 7,500 users," the report stated.

Subversion is available for free download from the CollabNet site, www.collab.net. It runs on Windows, Linux, and Solaris. Major users include Reuters, Philips Medical Systems, Capgemini, and Barclays Global Investors.

CollabNet supplies seven of the 45 committers who commit about 60% of the code going into Subversion. CollabNet employs 16 of its 100 active contributors. In 2002, two years into the project, it employed the equivalent of three full-time Subversion developers.

CollabNet is located in Brisbane, Calif., and is an independent software vendor with 230 employees. It was founded by members of the Apache Server project to capitalize on the open source development methods that were used to generate the popular Apache Web Server. It produces the CollabNet OnDemand software project management system, with Subversion as a key component.