BitKeeper

BitKeeper. It is a proprietary, distributed version control system originally developed by Larry McVoy beginning in the late 1990s. The software was designed to handle the needs of very large-scale, distributed development projects, most famously serving as the primary tool for the Linux kernel development community for several years. Its architecture and feature set significantly influenced the design of subsequent open-source systems like Git.

History

The development of the software was initiated by Larry McVoy, a former engineer at Sun Microsystems, who was inspired by the collaborative model of the Linux kernel project. He founded BitMover, Inc. to commercialize the product, with its first official release occurring in early 2000. Its adoption by prominent open-source projects, most notably under the stewardship of Linus Torvalds, provided it with immense visibility and credibility within the software engineering world. This period of collaboration ended in 2005, leading to the creation of Git by Linus Torvalds as a direct replacement, a move that fundamentally altered the landscape of version control.

Features

The system pioneered a fully distributed model, allowing every developer's working copy to function as a complete repository with full history and version-tracking capabilities. Key innovations included efficient handling of large repositories and binary files, sophisticated change merging algorithms, and strong support for disconnected operation. Its "changeset" model and SHA-1 hash-based data integrity mechanisms were particularly influential concepts later adopted and refined by other systems. The tool also provided a web interface for code review and browsing, integrating workflow management directly into the version control process.

Licensing and business model

It was distributed under a proprietary license, though BitMover, Inc. offered free-of-charge licenses for open-source projects and individual developers under a specific "Community" version. This business model was a source of ongoing tension, as it required users to accept terms that restricted certain activities, such as reverse engineering or developing competing tools. The controversial nature of its license, especially clauses perceived as antagonistic towards the free software philosophy championed by the Free Software Foundation, was a primary catalyst for the community's eventual shift away from the platform.

Adoption and impact

Its most significant adoption was by the Linux kernel development team, which used it from 2002 to 2005 to manage the massive, globally distributed project. This successful deployment proved the viability of distributed version control for large-scale, complex software efforts. Other notable projects, including the X Window System and parts of the OpenJDK, also utilized it during this period. Its profound impact is most clearly seen in the design of Git, which replicated and extended its distributed architecture, and to a lesser extent in Mercurial, which emerged around the same time.

Controversies

The primary controversy centered on its proprietary license and the perceived risks it posed to the autonomy of the open-source community. A pivotal incident involved the revocation of the free license for Andrew Tridgell, who was accused of developing a tool to interoperate with the system, which BitMover, Inc. claimed violated its license. This action, seen as hostile by many in the community, directly prompted Linus Torvalds to initiate the Git project. The ensuing departure of the Linux kernel team and other major projects marked a decisive moment in the ascendancy of open-source version control tools.

Category:Version control systems Category:Proprietary software Category:Software using the Apache license