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Diffstat (limited to 'VERSIONING')
| -rw-r--r-- | VERSIONING | 154 |
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diff --git a/VERSIONING b/VERSIONING new file mode 100644 index 0000000..dbfec92 --- /dev/null +++ b/VERSIONING @@ -0,0 +1,154 @@ +APACHE 2.x VERSIONING +===================== +[$LastChangedDate: 2007-02-28 17:12:06 +0000 (Wed, 28 Feb 2007) $] + + +INTRODUCTION +------------ +The Apache HTTP Server project must balance two competing and disjoint +objectives: maintain stable code for third party authors, distributors and +most importantly users so that bug and security fixes can be quickly adopted +without significant hardship due to user-visible changes; and continue the +development process that requires ongoing redesign to correct earlier +oversights and to add additional features. + +The Apache HTTP Server, through version 2.0, used the Module Magic Number (MMN) +to reflect API changes. This had the shortcoming of often leaving users +hunting to replace binary third party modules that were now incompatible. +This also left module authors searching through the API change histories to +determine the exact cause for the MMN change and whether their module was +affected. + +With the simultaneous release of Apache 2.2-stable and Apache 2.3-development, +the Apache HTTP Server project is moving towards a more predictable stable +release cycle, while allowing forward progress to occur without concern +for breaking the stable branch. This document explains the rationale between +the two versions and their behavior. + + +STABLE RELEASES, 2.{even}.{revision} +------------------------------------ + +All even numbered releases will be considered stable revisions. + +Stable revisions will retain forward compatiblity to the maximum +possible extent. Features may be added during minor revisions, and +features may be deprecated by making appropriate notations in the +documentation, but no features may be removed. + +In essence, that implies that you can upgrade from one minor revision +to the next with a minimum of trouble. In particular, this means: + + * The Module API will retain forward compatibility. + It will not be necessary to update modules to work with new + revisions of the stable tree. + + * The run-time configuration will be forward compatible. + No configuration changes will be necessary to work with new + revisions of the stable tree. + + * Compile-time configuration will be forward compatible. + The configure command line options that work in one release + of the stable tree will also work in the next release. + +As always, it will be necessary to test any new release to assure +that it works correctly with a particular configuration and a +particular set of modules, but every effort will be made to assure +that upgrades are as smooth as possible. + +In addition, the following development restrictions will aid in +keeping the stable tree as safe as possible: + + * No 'Experimental' modules; while it may be possible (based on API changes + required to support a given module) to load a 2.3-development module into + a 2.2-stable build of Apache, there are no guarantees. Experimental + modules will be introduced to the 2.3-development versions and either + added to 2.2-stable once they are proven and compatible, or deferred + to the 2.4-stable release if they cannot be incorporated in the current + stable release due to API change requirements. + + * The stable subversion tree should not remain unstable at any time. Atomic + commits ought be used to introduce code from the development version to the + stable tree. At any given time a security release may be in preparation, + unbeknownst to other contributors. At any given time, testers may be + checking out SVN trunk to confirm that a bug has been corrected. And as + all code was well-tested in development prior to committing to the stable + tree, there is really no reason for this tree to be broken for more than + a few minutes during a lengthy commit. + +In order to avoid 'skipped' release numbers in the stable releases, the +Release Manager will generally roll a release candidate (APACHE_#_#_#_RC#) +tag. Release Candidate tarballs will be announced to the +stable-testers@httpd.apache.org for the stable tree. Then, the participants +will vote on the quality of the proposed release tarball. + +The final APACHE_#_#_# tag will not exist until the APACHE_#_#_#_RC# candidate +has passed the usual votes to release that version. Only then is the final +tarball packaged, removing all -rc# designations from the version number, and +tagging the tree with the release number. + +DEVELOPMENT RELEASES, 2.{odd}.{revision} +----------------------------------------- + +All odd numbered releases designate the 'next' possible stable release, +therefore the current development version will always be one greater than +the current stable release. Work proceeds on development releases, permitting +the modification of the MMN at any time in order to correct deficiencies +or shortcomings in the API. This means that modules from one development +release to another may not be binary compatible, or may not successfully +compile without modification to accomodate the API changes. + +The only 'supported' development release at any time will be the most +recently released version. Developers will not be answering bug reports +of older development releases once a new release is available. It becomes +the resposibility of the reporter to use the latest development version +to confirm that any issue still exists. + +Any new code, new API features or new ('experimental') modules may be +promoted at any time to the next stable release, by a vote of the project +contributors. This vote is based on the technical stability of the new +code and the stability of the interface. Once moved to stable, that feature +cannot change for the remainder of that stable release cycle, so the vote must +reflect that the final decisions on the behavior and naming of that new +feature were reached. Vetos continue to apply to this choice of introducing +the new work to the stable version. + +At any given time, when the quality of changes to the development branch +is considered release quality, that version may become a candidate for the +next stable release. This includes some or all of the API changes, promoting +experimental modules to stable or deprecating and eliminating older modules +from the last stable release. All of these choices are considered by the +project as a group in the interests of promoting the stable release, so that +any given change may be 'deferred' for a future release by the group, rather +than introduce unacceptable risks to adopting the next stable release. + +Third party module authors are strongly encouraged to test with the latest +development version. This assures that the module will be ready for the next +stable release, but more importantly, the author can react to shortcomings +in the API early enough to warn the dev@httpd.apache.org community of the +shortcomings so that they can be addressed before the stable release. The +entire burden is on the module author to anticipate the needs of their module +before the stable release is created. Once a new stable release cycle has +begun, that API will be present for the lifetime of the stable release. Any +desired changes in the stable versions must wait for inclusion into the next +release cycle. + +When deciding to promote a development tree to being stable, a determination +should be made whether the changes since the last stable version warrant a +major version bump. That is, if 2.2 is the current stable version and 2.3 is +'ready' to become stable, the group needs to decide if the next stable +version is 2.4 or 3.0. One suggested rule of thumb is that if it requires +too much effort to port a module from 2.2 to 2.4, then the stable version +should be labeled 3.0. + +In order to ease the burden of creating development releases, the process +for packaging a development releases is less formal than for the stable +release. This strategy reflects the fact that while in development, versions +are cheap. Development releases may be classified as alpha, beta, or GA +to reflect the group's perceived stability of the tree. Development releases +may be made at any time by any committer. + +Please read the following link for a more detailed description of the +development release strategy: + +http://httpd.apache.org/dev/release.html |