This page is based on the source code management appendix (Appendix B) in Ship It!.
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Source Code Management Tools
Source Code Management (SCM) programs (also generically known as
version control systems) keep track of your code and the changes you
make to it. In addition, a good SCM associates specific versions of the
code with important milestones, e.g., a product release.
A free, open-source client-server SCM. Does everything you need, but the
command-line interface is a bit arcane. CVS is used by companies large and
small all over the world.
The self-avowed replacement for CVS, it does most of what CVS does, plus a lot
more. Like CVS, its open-source and free.
MS Visual SourceSafe--
Microsofts SCM, its integrated with a lot of their development tools and IDEs.
If your shop paid for Microsofts development tools, youve probably already
paid for SourceSafe and have a license waiting to be used.
BitKeeper is a commercial product that the Linux kernel developers used for
several years, and they have reported a significant increase in productivity as
Where the source code is stored.
Your local copy of the source code on your machine. You check
code out of the repository into your workspace, work on it for
awhile, and then check it back into the repository.
The program you run on your machine that interfaces with the
repository through the server.
The program that sits in front of the repository and deals with the
You branch a project so that you can have multiple development
paths with that project. For example, one branch of a project
would be used for bug fixes on the current version, and another
branch would be used to develop the next version.
The way you identify a specific version of a file, directory, project,
When two or more developers are working on the same file, the
changes must be merged.
How the SCM determines who can make a change to a file. In a
pessimistic locking system, only one person at a time can make
changes to a file. In an optimistic system, many people can make
changes, and all the changes are automatically merged when the
file is checked in.
The Cost of a Tool
Many development teams prefer to use free tools, while others
prefer commercial products with support contracts. We tend
to favor tools that are freely available and get support from the
user community, but we dont pick tools based on the cost. We
choose tools based on what works. If several tools can fill the
need our teamhas, well pick the free one. Youll need to figure
out what works in your environment.
How to Choose:
Tags-Is it easy to tag specific versions of your source code? Is it
easy to use tags to access that code?
Merging-Are your merges manual or automatic?
Multiproject projects-Can you include other projects, modules,
and versions in your project? How hard is it to define interproject
Ease of use
Does the system integrate with the the editors or IDEs your team is
using? Can it be embedded within your build scripts? Remember,
if its not convenient to use, nobody will use it.
Can the system handle all your files? Projects? Users? Without
losing or corrupting files?
Are the basic operations fast enough to be worthwhile, or will people
bypass them because they dont want to wait?
For More Information:
See Practice 2, Manage Assets, on page 20 of Ship It!