Three Stages in SCM History

One reason we have so many distinct definitions of SCM, is that we are not speaking of the same thing. Thus, the interest of classification. The one I propose here is loosely chronological, although it doesn't pretend to give a complete record of history, first of all because of the preexistence of a CM in the industry, totally unrelated to software.

The criterion I propose is the kind of artefacts used for mapping the concept of configuration item:

1. The line of text is the basis of support for the first stage, built upon the Unix tools, diff and patch, and for which the concept of Change Set^? (in a first acception) is essential.
2. The source file is the basis for the second stage.
3. The unconstrained file object, stereotypically taken as a derived object, is the basis for the third.

Obviously, the overwhelming mass of the current SCM tools, as well as arguably the main stream of development, lies in the second category, with a large share even today, and 'still going strong', in the first. The third one is almost (?) only supported, however imperfectly, by base ClearCase.

-- MarcGirod - 27 Feb 2005