DistributedSCM

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Distributed SCM (Software Configuration Management)

A distributed SCM tool is designed to support a model in which each repository is loosely coupled to many others. Each repository contains a complete set of metadata describing one or more projects. These repositories may be located almost anywhere. Individual developers only need access to their own repositories, not to a central one, in order to commit changes.

In the distributed approach, each developer works directly with their own local repository, and changes are shared between repositories as a separate step. This mode of operation allows developers to work without a network connection, and it also allows developers full revision control capabilities without requiring permissions to be granted by a central authority. One of the leading proponents of distributed revision control is Linus Torvalds, developer of the Linux kernel. Distributed systems inherently allow multiple simultaneous editing.

Distributed SCMs provide mechanisms for propagating changes between repositories.

Distributed SCMs are in contrast to CentralisedSCMs.

Examples

• BitKeeper (`bk`) - proprietary (was used in Linux kernel development December 1999 - April 2005)
• GNU Arch (`tla`) aka. GNU Arch 1 — the original Arch. Created and written mainly by Tom Lord, currently maintained by Andy Tai.
• Bazaar-NG (`bzr`) — written in Python. Decentralised and easy to use. Can losslessly import Arch archives. Sponsored by Canonical Limited
• Monotone — full-decentralized in a P2P way, with emphasizis on SCM security: e.g. cryptographic version naming and client-side RSA certificates (was considered for Linux kernel development).
• Mercurial (`hg`) — written in Python. Very fast, lightweight, portable, and easy to use.