[erlang-questions] Version numbering scheme change and the implication / Re: [ANN] Erlang/OTP 17.0-rc1 has been released.

[Loïc Hoguin]

Sounds good.

One question though. Does that mean the current cycle of having a major 
release every year will be changed, or should we still more or less 
expect a new major at the beginning of the year and three or four minor 
releases after that?

I hope that having source code only and a proper PATCH number will allow 
much faster release of fixes when a release is significantly broken 
(like for example the R16B03's syntax_tools application issue -- 
R16B03-1 took a long time to get released).

On 02/07/2014 12:20 PM, Andreas Schumacher wrote:
> We changed the version scheme for two reasons: For the first, we
> abandoned the R-version scheme, since it has a meaning inside Ericsson
> that differs from how we used it; that caused some confusion. Secondly,
> we adapted a version scheme that allows us to bookkeep fine-grained
> patches on arbitrary OTP versions to our customers with support agreements.
>
> The new version scheme is *not* semantic versioning; although, it has
> been inspired by it. We do not want to use semantic versioning (as
> defined by http://semver.org/) out of the box since it does not fit our
> needs. Most importantly, we must be able branch out from any old version
> and also be able to do so multiple times. This is not possible when
> limited to only using MAJOR.MINOR.PATCH as version numbers. For example,
> if we have released 17.0, 17.0.1, and 17.0.2 we may have to release a
> patch based on 17.0.1. In this case it will be given the version 17.0.1.1.
>
> A new MAJOR release is denoted with <X>.0, where <X> is incremented by
> one at the delivery of a new major release, which may contain potential
> incompatibilities.
>
> A pre-release is denoted with <X>.0-rc<N>, where <N> starts with 1 at
> the delivery of the first pre-release, and is incremented by one for
> each subsequent pre-release. "-rc0" will be used during development up
> to the first release candidate. Pre-releases <X>-rc<N> sort before <X>.
> Apart from <X>-rc<N>, there are no plans for other special parts;
> although that might change if the need arises.
>
> A MINOR and/or PATCH (bug-fix) release is denoted with <X>.<Y>.<Z>, where:
> - <Y> is set to 0 when <X> is incremented and is incremented by one when
> new (minor)
>    functionality is released. <Y> is used even when <Y> == 0.
> - <Z> is set to 0 when <X> or <Y> is incremented, and incremented by one
> when only bug
>    fixes are released. <Z> is not used when <Z> == 0, unless [support
> patches] patches are based on that version; see below.
>
> Everything in a version V0 = <X>.<Y0>.<Z0> is included in a version V1 =
> <X>.<Y1>.<Z1> if V1 is greater than V0. V1 > V0 if Y1 > Y0 || (Y1 == Y0
> && Z1 > Z0).
>
> The OTP major release and the complete OTP version can be retrieved from
> erlang code using the following:
>
>     1> erlang:system_info(otp_release).
>     "17"
>     2> erlang:system_info(otp_correction_package).
>     "17.0-rc1"
>
> NOTE: The name of the argument "otp_correction_package" will be changed
> to "otp_version." In addition, a corresponding flag "otp_version" will
> be added to the erl command, in order to allow the extraction of the
> complete version number from command line tools.
>
> Version changes in applications imply a version change on OTP level, but
> they are not propagated one-to-one; especially, a change of the major
> version of an application does not necessarily imply a change of the
> major version at the OTP level. The mapping is a case-by-case decision
> that depends on the application, the type of functionality, impacts on
> backward compatibility, etc.
>
> It is basically only the releases of the form <X>.<Y>.<Z> that are of
> interest for the Erlang open source community. However, from OTP 17.0 we
> will only deliver source code releases [even to our customers with
> support agreements]; and thus, even traces of support-patch
> release-versions on top of those regular releases are going to be
> visible in the public Erlang/OTP Git repository. The following is a
> brief description of the format of those patch releases:
>
> When branching out, we add ".1" at the end of <X>.<Y>.<Z>, unless this
> version number has already been used. If it has already been used, we
> search for an unused version number by adding more and more ".0" between
> the version we are branching from, and the ".1" that we add at the end.
> For example, 17.0.1.1, 17.0.1.0.1, 17.0.1.0.0.1, and 17.0.1.0.0.0.1 are
> all versions of modifications based on version 17.0.1.
>
> When basing a patch or a feature on an already branched version that do
> not require any new branching, we increase the last part of the version.
>
> When versions have more than the ordinary three parts MAJOR.MINOR.PATCH,
> you cannot
> draw any conclusions about the specific modifications in the version,
> but you can see what the modifications are based on.
>
> The Erlang/OTP Team at Ericsson
>
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-- 
Loïc Hoguin
http://ninenines.eu