What version numbering scheme to use?

Question

I'm looking for a version numbering scheme that expresses the extent of change, especially compatiblity.

Apache APR, for example, use the well known version numbering scheme

<major>.<minor>.<patch> example: 4.5.11 

Maven suggests a similar but more detailed schema:

<major>.<minor>.<patch>-<qualifier>-<build number> example: 4.5.11-RC1-3732 

Where is the Maven versioning scheme defined? Are there conventions for qualifier and build number? Probably it is a bad idea to use maven but not to follow the Maven version scheme ...

What other version numbering schemes do you know? What scheme would you prefer and why?

Answer 1

I would recommend the Semantic Versioning standard, which the Maven versioning system also appears to follow. Please check out,

http://semver.org/

In short it is <major>.<minor>.<patch><anything_else>, and you can add additional rules to the anything else part as seems fit to you. eg. -<qualifier>-<build_number>.

Answer 2

Here is the current Maven version comparison algorithm, and a discussion of it. As long as versions only grow, and all fields except the build number are updated manually, you're good. Qualifiers work like this: if one is a prefix of the other, longer is older. Otherwise they are compared alphabetically. Use them for pre-releases.

Seconding the use of semantic versioning for expressing compatibility; major is for non-backwards compatible changes, minor for backward-compatible features, patch for backward-compatible bugfixes. Document it so your library users can express dependencies on your library correctly. Your snapshots are automated and don't have to increment these, except the first snapshot after a release because of the way prefixes are compared.