F22 System Wide Change: Legacy implementations of the Java platform in Fedora

Robert Marcano robert at marcanoonline.com
Thu Feb 26 15:20:04 UTC 2015


On 02/24/2015 05:04 AM, Jaroslav Reznik wrote:
> = Proposed System Wide Change: Legacy implementations of the Java platform in
> Fedora =
> https://fedoraproject.org/wiki/Changes/LegacyJDKsInFedora
>
> Change owner(s): Jiri Vanek <jvanek at redhat.com>
>
> Currently Fedora supports one main Java runtime and Java Development Kit (JDK)
> and from time to time one future JDK as a tech preview. This change should be
> set of rules, which will enable community to maintain legacy JDKs. Please
> note, people are bugging main JDK maintainers pretty often with this, and to
> allow them to maintain legacy JDKs is a step in right direction.
>
> * This Change is announced after the Change Submission Deadline as an
> exception to the process. May not be approved for proposed Fedora release. *
>
> == Detailed Description ==
> This is no real work proposal. The result of this proposal is set of rules,
> which will allow community maintainers to pack any legacy jdk and will be
> ensuring that this JDKs will not conflict by any other JDK and will smoothly
> integrate to system. The results are summarized here, and pledged for
> discussion until final resolution is done.

I think for this to work, real work should be done by all Java 
packagers. There is no advantages of being able to install any community 
maintained legacy JDK if I can't use already packaged code. An example 
PostgreSQL JDBC driver is currently built with Java 8 bytecode level, it 
can't be used with any previous Java release. This happen because 
upstream developers frequently forget to add the --target javac command 
line argument for the minimum supported Java release they support (and 
work with upstream to add it). So a lot of packages need to be patched 
because they will target the built time Java bytecode level.

>
> === Proposed rules ===
> 0. '''Main JDK maintainers are not never ever responsible for any legacy jdk.
> This must remain clear'''
>
> ==== option one - introducing new packages - preferred ====
> 1. main jdk is proclaimed as dead as it was until now.  The new jdk is derived
> as new package prviousName-legacy
>   1. so from killed java-1.7.0-openjdk will become new package java-1.7.0-
> openjdk-legacy
>   2. next main jdk do Obsolete previous one as usually
> 2. new package '''must''' not do any virtual provides (aka java,java-devel)...
> (protection against random pull by as dependence)
>   1. it provides only itself by name
> 3 its priority '''must''' be kept on less digits (right now it would be 5)
> then main jdk (protection against winning in alternatives after update)
>   1. the automated check as https://bugzilla.redhat.com/show_bug.cgi?id=1189084
> are '''mandatory'''
> 4. at least one of the main-jdk's members '''must''' be set as comaintainer
> (to watch the commits and save the world if necessary)
> 5. new  package '''should''' to follow both original jdk (ideally not change
> at all (except source updates and necessary)) and current main jdk as close as
> possibly
>   1. here it requires some common sense and a lot of testing if integration
> with system is as expected
> 6. as it is generally not new package, the review process '''should''' be only
> formal - to know maintainer and to create cvs repo
>   1. this is quite important, otherwise the new maintainer can become really
> frustrated, and we are forcing the "dead" package over"orpahned" so the full
> review (especially in alignment with rule 5) really should not be forced.
>   2. on the contrary, rules agreed here '''must''' be checked.  (even the
> number 5)
> 7. all depending packages '''must''' keep requiring java-headless or java (and
> BuildRequires java-devel). Requirements on any exact jdk - or even worse on
> any exact legacy jdk are forbidden and needs FESCO exception.
>
> This option is forcing maintainers to fight with the name x current setup of
> alternatives. However, the work should be minimal. But it makes the update
> path pretty clear and it keeps users well protected against legacy jdk.
>
> ==== option two - orphaning legacy jdks and ensure update path ====
> 1. main JDK is only orphaned when new main JDK landed
>   1. it do '''not''' Obsolate previous jdk
> 2. other rules (2-7) are same
>
> This is making life of legacy JDK maintainers a bit simpler. But I don't know,
> how to ensure proper "obsolete" implementation in this case.
>
> == Scope ==
> * Proposal owners: are responsible for initial setup of those guidelines.
> The FESCO, the owners and pssible legacy JDKs maintainers have to agree on
> those rules. New legacy JDK can be then added anytime in Fedora lifecycle.
> * Other developers: no developers
> * Release engineering: in ideal case, no release engineer needed
> * Policies and guidelines: The proposal may split to proposal and "Legacy JDKs
> in Fedora guidelines" pages
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