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Request for Comments: PECL Versioning
- Author: Steph Fox, Pierre A. Joye
- Status: Work in progress
Currently, PECL versioning is fairly anarchic. It is impossible to determine the state of an extension or if an update will break the backward compatibility with previous versions (or work with a given PHP release) without a long try&fail process. The distribution of windows PECL binaries also needs to have a reliable version information in the DLLs, both in the DLLInfo resources (visible in the file info properties) as well as runtime (phpinfo, get_version() etc.). This problem has to be fixed to bring PECL to a higher quality and reliability level.
Some Facts and Figures
There are currently 214 modules in PECL. Of these:
- 1 is written in PHP
- 3 are SAPIs
- 2 are no longer hosted in PECL (and should be deleted)
- 1 doesn't declare a zend_module_entry
- 1 doesn't have versioning capability (pre-PHP 4.1?)
- 1 was a CVS error (and should be deleted)
- 1 is the timezone library for ext/date, and probably has non-standard versioning requirements
Of the remaining 204:
- 13 already use PHP_EXTNAME_VERSION declared in php_extname.h, but don't use -dev
- 25 already declare and use a versioning macro in php_extname.h, but the name could be anything
- 27 already declare and use a versioning macro somewhere in the source
- 3 do the whole thing in reverse and use the release version from package.xml
- 136 either hard-code the version, use $Id alone, use $Revision alone or ignore the whole thing
Version Info Requirements
Each PECL package has to follow the following requirements:
- Declare PHP_EXTNAME_VERSION in php_extname.h
- Use PHP_EXTNAME_VERSION in every place where the version information is used, for example in both the zend_module_entry declaration and PHP_MINFO() (the phpinfo() source)
- The “-dev” postfix has to be used in CVS, in each branch. At packaging time, remove it, create your package, tag the CVS tree and add it again
- Use a recognized versioning structure (so that version_compare() can be useful and users can easily see which version they have). See Version naming for a detailed explaination.
Optional version information
- The cvs $Revision$ or $Id$ (or their equivalent in other source control system) placeholder can be used without restriction but it can't be used as a version number
There is two kind of packages in PECL, a normal PHP extension providing a set of APIs (http, enchant, fileinfo)and extension providing only data (timezonedb). Normal extensions have to use the standard version number defined below as the data package can use a date time version:
- Standard version: 2.2.11 Major
- Date time version: 2008.2 (for february 2008) or 2008.04.4 (April 4th, 2008)
Detailed version number explanation (thanks to the PEAR project which already uses this standard versioning)
- A version number must include a major, a minor and a patch level version number. Please note that all are version numbers are mandatory.
- A package version has a “state” (as indicated in the package.xml file), which describes the maturity. The state may be one of “dev”, “alpha”, “beta”, “RC” or “stable” (listed in the order of code maturity). Please note that the state “RC” is achieved by using the state “beta” and appending the version number with “RC” followed by an integer
- PEAR doesn't recognize hyphens (that is, x.x.x(-dev|-alpha|-beta|RC)) in a package version string - use x.x.xax|x.x.xbx instead of than -alpha|-beta.
- A backwards-compatability break may include feature additions
- A feature addition may include bug fixes
- The version name is always computed on the version name of the release, on which the new release is based, if one exists.
- The version number must be greater or equal than 0.1.0
- All initial releases of a package with states “dev”, “alpha”, or “beta” prior to the first stable release should have a version number less than “1.0.0”.
- The first release with state “RC” or “stable” must have a version number of “1.0.0”.
- There may not be a stable release unless there has been at least one release before with the same major version.
- BC may only be broken in releases that have a version number of “x.0.0” with a state lower than stable or that have a version number below “1.0.0”. As a converse only releases that break BC or that have a version number of “1.0.0” may increase the major version number compared to the previous release.
- Features may only be added in releases that have a version number of “x.y.0” (where “y > 0”). As a converse the minor version may only be increased in releases that add features.
- For releases that only fix bugs the version number should be “x.y.z” (where “z > 0”) unless the maturity state is increased. As a converse the patch level number should only be used (as in non zero) in releases that only fix bugs.
- The state should always be added as a suffix unless the state is “stable” (please note that as stated above the state “beta” is used for beta releases and for release candidates). The suffix consists of the state followed by a number which is incremented with every subsequent release with the same state.
- In the lifecycle of a package each major version increase it is only once (once from major version number 0 to 1, from 1 to 2 etc.).
Example: Lifecycle of a package
|development release||initial release||0.1.0dev1||initial version|
|development release||features added||0.2.0dev1||BC break allowed|
|alpha release||features added||0.9.0alpha1||BC break allowed - but discouraged|
|beta release||bug fixes||0.9.0beta1||BC break allowed - but discouraged|
|beta release||bug fixes||0.9.0beta2||BC break allowed - but discouraged|
|RC release||bug fixes||1.0.0RC1||BC break allowed - but heavily discouraged|
|stable release||no changes||1.0.0||BC break is not allowed|
|stable release||bug fixes||1.0.1||BC break is not allowed|
|development release||features added||1.1.0dev1 BC break is not allowed|
|beta release||bug fixes||1.1.0beta1||BC break is not allowed|
|stable release||bug fixes||1.1.0||BC break is not allowed|
|stable release||features added||1.2.0||BC break is not allowed|
|development release||major changes||2.0.0dev1||BC break is allowed|
|alpha release||major changes||2.0.0alpha1||BC break is allowed - but discouraged|
|beta release||bug fixes||2.0.0beta1||BC break is allowed - but discouraged|
|RC release||features added||2.0.0RC1||BC break is allowed - but heavily discouraged|
|RC release||bug fixes||2.0.0RC2||BC break is allowed - but heavily discouraged|
|stable release||bug fixes||2.0.0||BC break is not allowed|
|stable release||bug fixes||2.0.1||BC break is not allowed|
PECL Packages also distributed as Core modules
Johannes Schlueter - as Release Master of the PHP 5.3 series - made it known early in the proceedings that he has concerns over -dev, -alpha or -beta tags appearing in PHP core module versions. There's no process in place to export PECL releases into the PHP core; many of the modules in PECL are symlinked into the PHP core, affecting both snapshots and releases. This has benefits for the PECL modules concerned, in that they get far more testing than they otherwise might during the PHP development cycle, but the point remains that they are linked directly rather than filtered through an independent PECL release process.
The idea of using the tag '-core' rather than '-dev' to reflect the status of those dual-nature extensions came up. The PECL versioning could then remain x.x.x (no tag) during PECL releases, with the version number itself used to reflect alpha/beta development status. Christopher Jones of Oracle voiced his concern regarding core PECL modules in separate development branches, which happens with core symlinking (and can of course occur manually too). “Should the version in CVS HEAD be tagged -core6?” Pierre Joye recommended that module versions with a conflicting API simply reflect this in the version number, e.g. 1.0.3-core for PHP 5.* and 2.0.3-core for PHP 6. The PECL releases would be 1.0.3 and 2.0.3 respectively, and the version bumped to 1.0.4-core/2.0.4-core following release.
Feedback on this subject would be appreciated!