[Zope3-dev] The Zope Software Certification Program and Common Repository Proposal

Stephan Richter srichter at cosmos.phy.tufts.edu
Mon Feb 20 16:31:03 EST 2006

Hello everyone,

With the development of Zope 3, the Zope developers committed to a new 
development process and higher software quality guidelines. With the adoption 
of Zope 3 technologies in the wider Zope community, we should also start 
using the process for third party package development.

I have spent the last two weeks working on a proposal that defines a Zope 
Software Certification Program (ZSCP) and a Common Repository that implements 
this process. The proposal is attached to this mail. I welcome any comments 
about it!

In the pre-publication phase of the proposal, I have worked with a small 
committee to receive initial feedback. For the purpose of this proposal, I 
will not be representing a particular Zope sub-community, but instead act as 
a mediator among the parties of interest. I will try my best to answer all 
concerns and comments in a neutral manner.

I would like to thank all pre-proposal committee members for their time and 
valuable input.

Thanks for your time!


P.S.: Sorry for the cross post!
Stephan Richter
CBU Physics & Chemistry (B.S.) / Tufts Physics (Ph.D. student)
Web2k - Web Software Design, Development and Training
-------------- next part --------------
The Zope Software Certification Program and the Common Repository

:Version: 0.7

:Author: Stephan Richter

1. Introduction

This section intends to provide the reader with an overview where the idea of
this proposal originated and what it tries to accomplish.

1.1. Motivation

It took Zope 3 about four years to be developed, starting from an idea to the
acceptance of the technology by most of the wider Zope community. Now its
acceptance grows by the minute. But this also means that the code written for
Zope 3 increases in a similar fashion. Already people have published several
collections of packages:

  * ``hurry`` -- This small library was developed by Infrae as part of a
    customer engagement. It features an advanced file field/widget and a nice
    query API for the catalog. There are currently 3 contributed packages.

  * ``schooltool`` -- Even though SchoolTool has not actively released
    packages of their code base, it contains several features that are worth
    looking at, including the relationship, pluggable traverser, and dynamic
    test setup packages. There are about 4 generic packages.

  * ``tiks`` -- Developed by Projekt01, the tiks packages are designed to
    provide useful features for a wide range of Zope 3 applications, including
    CMSs. There are currently 30+ contributed packages.

  * ``z3ecm`` -- While it does not seem that the development is making much
    progress, the ECM repository features several very interesting packages,
    including a document workflow (based on zope.wfmc) and cpsskin for Zope
    3. There are currently 2+ contributed packages.

  * ``zc`` -- Zope Corporation recently released several of the packages they
    developed during customer engagements. Some of their released packages are
    already in the core, others are only useful in more specific
    environments. There are currently 14+ contributed packages.

(Names sorted alphabetically.)

Right now all of those efforts are totally uncoordinated. Even though this is
an Open Source community, the communication is often all but open. In fact,
already packages duplicate functionality; for example, several packages
provide JS-based highly-polished widgets.

It is also difficult to gauge the quality of the packages. Surely a developer
can look at them and get a general idea, but one might not have the time to do
that. By the time developers notice that a package is insufficiently
thought out, they might be stuck with it. There should be a way of stating the
quality of a package.

Another topic that has been also very important to people is the management
of package versions and package dependency. This is an unsolved issue and even
though there are emerging technologies, for example eggs, the Zope community
needs to provide a solution to the problem as part of the development process.

1.2. Goals

The two main goals of this proposal are to define a process of verifying
package quality, called the Zope Software Certification Process (ZSCP), and to
lay out a repository, called the Common Repository, that provides developers
with a space to implement the process. As a direct consequence, it is
anticipated that the various Zope development communities will reunite to
develop a common, high-quality code base, by stressing the skill sets and best
practices of each contributor. With Zope 3 as the communities' new
base-technology, it is possible to easily share code among various projects,
even if they are still Zope 2 based. Of course, as time passes, the
distinction between Zope 2 and 3 will fade.

Here are some specific items that are addressed in this document:

  * Well-defined Process, the Zope Software Certification Program (ZSCP)

    The Zope 3 community has a semi-formal process in place to ensure the
    quality of packages in the core. However, this process does not extend to
    third party code, let alone code outside of the zope.org
    repository. On the other hand, Plone also uses the collective for core
    packages without any control over the process or quality. This proposal
    will define a process for ensuring the quality of packages and for
    upstream movement: in other words, the way a third-party package could
    become a core package.

  * Repository Unification

    Currently we have several repositories scattered around in many
    places. No-one has access to all the repositories and thus small code
    improvements are hard to make; the overhead is large. If one finds
    something wrong with the code, one either has to write a mail or create a
    bug report. And that often requires one to sign up to yet another mailing
    list or create a user account for yet another web site. Thus, this
    proposal suggests a common repository for all generically useful Zope 3
    add-on packages.

  * Quality Packages

    There is a natural desire for any developer to know what they are getting
    into when they are using a certain package, a baseline of quality that can
    be expected. While the Zope 3 community has some ideas of what that
    baseline is for the core, it is not well defined and applied uniformly. This
    proposal defines clear quality guidelines.

  * Clear Dependency Declarations

    One of the greatest frustrations in the Zope community, especially in
    Plone, is the complex non-closed tree of dependencies of packages. While
    this issue cannot be solved for the entire community, this proposal
    provides an attempt to clearly define dependencies for the packages living
    in the official repository.

  * Common License

    The Zope community at large uses mainly two licenses, the ZPL and the
    GPL. (Yes, other licenses are also used.) Dealing with multiple licenses
    is a pain, especially for Zope's consumers. This proposal discusses the
    current situation and proposes a resolution.

  * Marketing Effect

    People commonly say, Zope does anti-marketing. And that is probably
    true. While a proposal like that cannot address this issue globally, it
    can at least address it from a technical/code-oriented side. It should be
    possible to use the certification of a package as a marketing tool. Of
    course, quality, clear dependencies, a common license, a predicatbale
    process, and having a one stop for all software are all marketting wins
    that are automatically achieved by implementing this proposal.

2. The Zope Software Certification Program

This section describes the process for Zope-related software to receive
quality certification.

2.1. Zope Community Process

Historically, the Zope community had no development process. This was in part
because the development of Zope 2 was controlled by Digital Creations (now
Zope Corporation) and testing-automation tools were not available at that
time. Also, Zope 2 lacked the necessary documentation. All this lead to an
accepted misuse of the API and often low quality software.

With the advent of Zope 3, procedures were set in place to ensure the quality
and documentation of the code. Guided by eXtreme Programming practices,
sprints were organized to educate the Zope community about the project and
have high-productivity development time, proposals were introduced to ensure
the proper discussion of a feature before implementation, and tests were
required to ensure the overall quality of the code base. This development
process is called the Zope Community Process.

While the Zope Community Process provides an excellent method for developing
community-driven projects like Zope 3, it (a) does not show how to produce
simple high-quality packages, (b) measure the quality, and (c) communicate the
state of a package to outsiders. The goal of the Zope Software Certification
Program (ZSCP) is (a) to clearly define the levels of software quality using a
metric system and (b) to communicate this information to our users, customers,
and prospective customers.

2.2. Audience

The audience for the Zope Software Certification Program (ZSCP) is
two-fold. On the one hand, it is desired to provide the developer with an
overview of quality packages, on the other hand, decision makers need to be
shown how seriously the Zope community takes the assurance of software

One common complain the Zope developers received from the Zope community was
about the non-existent organization of Zope's third party products. Everybody
can upload their product to zope.org, without any evaluation of quality,
version compatibility or documentation. The goal of the ZSCP and its Web site
is to provide a measurement of quality (see section 2.4.) measured as much as
possible by automated tools and by minimal developer verification. Also,
packages listed in the ZSCP *must* provide a set of meta-data that links the
user to various online resources. (See section 2.5.)

The message to the decision maker varies slightly based on his/her familiarity
with Open Source and Zope in particular. To the uninitiated decision maker the
ZSCP should send a message of technical and economic professionalism. The ZSCP
is a viable resource to understand the software quality requirements and the
process that enforces this quality. For more technically versed people, it
also provides a great overview of available features through add-on
packages. For the uninitiated decision maker it is also very important to know
that the Zope Foundation, a company-independent institution, fully supports
this program and its process.

The initiated decision maker already believes in Open Source and Zope, but
might be skeptical about other third-party packages. For him/her, the ZSCP
provides not only a searchable list of quality packages, but also guidelines
of what to expect of his/her developers in terms of software quality. Again,
the support of the Zope Foundation is reassuring to him that the program is

2.3. Certification Levels

There are 4 distinct levels for certification. They are defined in the list
below. The specific list of quality requirements for each level is provided in
section 2.4.

* ZSCP Listed

  Getting a package listed in the ZSCP system is the first step to obtain
  certification. Packages listed on the ZSCP Web site must adhere to the
  common package layout[1] and are subject to the automated testing as well as
  the quality assurance process. Listed packages must provide a full set of
  meta-data (as applicable) as defined in section 2.5.

  Packages at this level will fulfill roughly the same purpose as packages in
  the CMF/Plone Collective. It is one way to make a package publicly available
  and give it some exposure. At this level, the developer will not have to
  comply with many of the quality metrics. See section 2.4.

  .. [1] The common package layout is defined in section 3.2.

* ZSCP Level 1 Certified

  To be level 1 certified, the package must fulfill the requirements of listed
  packages. Additionally, it has to provide documentation, tests (in doctest
  format), conform to the package and coding style guidelines, and provide
  migration scripts, if applicable.

  Packages of this level are considered fit for the Zope 3 core with the
  reservation of the core developers to provide or require small improvements.

  At this stage one may identify the package as "ZSCP Level 1 Certified" in
  informal or promotional material.

* ZSCP Level 2 Certified

  To be level 2 certified, the package must fulfill the requirements of level
  1 certified packages. Additionally, it has to be demonstrated that the
  package integrates well into the Zope software stack by providing
  documentation in alternative sources (Web sites/API doc), provide standard
  installation methods and demonstrate the correct functioning of the
  migration scripts.

  At this stage one may identify the package as "ZSCP Level 2 Certified" in
  informal or promotional material.

* ZSCP Level 3 Certified

  To be level 3 certified, the package must fulfill the requirements of level
  2 certified packages. Additionally, it has to be demonstrated that the
  package has been successfully released during several Zope release cycles,
  has an active development community and an up-to-date support structure and

  At this stage one may identify the package as "ZSCP Level 3 Certified" in
  informal or promotional material.

2.4. Quality Metrics

The certification is meaningless without the precise definition of tasks that
have to be accomplished for each certification level. This section provides a
list of concrete items that have to be fulfilled for each certification level.


- x: A metric is required for the certification level.
- A: The metric check can be conducted automatically.
- Q: The metric check can be conducted quickly by human inspection.
- D: The metric check would be difficult to conduct by human inspection.

| Metric                                   | Check | List | Le 1 | Le 2 | Le 3 |
| Package Meta-Information (see sec. 2.5)  | A     |  x   |  x   |  x   |  x   |
| Test Coverage                            | A     |  0%  | >90% | >95% | >95% |
| Tests verified by Automated Test Runner  | A     |  x   |  x   |  x   |  x   |
| Doctest-based Testing                    | A,Q   |      |  x   |  x   |  x   |
| (or list reason for not using doctests)  |       |      |      |      |      |
| Tests pass on all supported platforms    | A,Q   |      |  x   |  x   |  x   |
| Minimal Documentation                    | A,Q   |  x   |  x   |  x   |  x   |
| (``README.txt`` file)                    |       |      |      |      |      |
| Complete Documentation                   | Q     |      |  x   |  x   |  x   |
| (Text files cover all of API)            |       |      |      |      |      |
| Extensive Documentation                  | D     |      |      |      |  x   |
| (lots of samples, API docs, tutorial)    |       |      |      |      |      |
| Documentation available online [1]       | Q     |      |      |  x   |  x   |
| Documentation available in Zope's apidoc | Q     |      |      |  x   |  x   |
| Common package structure                 | A,Q   |  x   |  x   |  x   |  x   |
| Follows Zope Coding Style Guide          | A,D   |      |  x   |  x   |  x   |
| Conform to user interface guidelines     | D     |      |      |  x   |  x   |
| (if applicable to package)               |       |      |      |      |      |
| Complete dependency list                 | A     |      |  x   |  x   |  x   |
| Standard installation method             | A,Q   |      |      |  x   |  x   |
| Release(s) with version number           | A,Q   |      |      |  x   |  x   |
| Up-to-date homepage                      | D     |      |      |      |  x   |
| Active support mailing list              | D     |      |      |      |  x   |
| Released for at least 3 Zope releases    | D     |      |      |      |  x   |
| Releases state required Zope version     | A,Q   |      |      |      |  x   |
| Multiple (3) Active Maintainers          |       |      |      |  x   |  x   |
| Data migration claimed                   | Q     |      |  x   |  x   |  x   |
| (if applicable)                          |       |      |      |      |      |
| Data migration auto-tested               | A     |      |      |  x   |  x   |
| (if applicable)                          |       |      |      |      |      |
| Data migration verified                  | D     |      |      |      |  x   |
| (if applicable)                          |       |      |      |      |      |
| Data migration well-tested               | D     |      |      |      |      |
| (if applicable)                          |       |      |      |      | [2]  |

.. [1] For small packages it will suffice, if the documentation is available
       via a Web site of the repository. For projects having a homepage, the
       documentation *must* be available there.

.. [2] To verify this metric would require an amount of resources that the
       Zope Foundation and community cannot provide. This metric might be
       removed, if the resources cannot be found over a long period of time.

2.5. Package Meta-Information

In order to quickly provide a developer with contextual information about a
given package, it is necessary to clearly define the meta-data that *must* be
available about a package. This section defines and explains each item.

This data is compatible with the Python Package Index (PyPI).

The format of the meta-data fields is as follows:

  Sec#. Name

  (Data Type, Multiplicity, Necessity)

  Field Description

  Example: example value

The following data description is known as the *Package Meta-Data Version 1.0*.

2.5.1. Package-name

(Bytes Line, single, required)

The dotted Python path of the package.

Example: ``zope.sample``

2.5.2. Name

(Text Line, single, required)

The commonly used name of the package.

Example: Sample

2.5.3. Summary

(Text Line, single, required)

A short description or summary of the package. It is also often interpreted as
the title.

Example: The Zope Sample Package

2.5.4. Description

(Text, single, optional)

A detailed description of the package's functionality. While it should contain
some detail, it should not duplicate the documentation of the README.txt file.

Example: The sample package for Zope does provide some sample features that
         can be useful for developers to learn about sample data
         development. It does so by providing ...

2.5.5. Home-page

(URL, single, optional)

A URL to the homepage of the package.

Example: http://www.zope.org/Products/sample

2.5.6. Author

(Text Line, multiple, required)

The name of the author of the package. The value should *not* contain the
author's E-mail address. This field can be specified multiple times.

Example: John Doe

2.5.7. Author-email

(E-mail Address, multiple, required)

The E-mail of the author of the package. This field can be specified multiple
times. Any entry X of the author field is matched with entry X of the author
email field. If this field is specified the length of the author field list
must match the length of the author email field list.

Example: john at doe.com

2.5.8. License

(Text Line, multiple, required)

The software license of the package. This field can specified multiple times,
to support dual-licensing.

Example: ZPL 2.1

2.5.9. Platform

(Text Line, multiple, required)

The operating system/platform the package is known to run on. This field can
be specified multiple times. ``All`` may be used, if the package is available
on all platforms Python is running on, i.e. the package is pure Python code.

Example: Unix

2.5.10. Classifier

(Classifier Text Line, multiple, optional)

A classification entry identifying the package. This field can be specified
multiple times.

Example: Programming Language :: Python
         Topic :: Internet :: WWW/HTTP
         Topic :: Internet :: WWW/HTTP :: Dynamic Content
         Topic :: Software Development :: Libraries :: Python Modules

2.5.11. Developers-mailinglist

(E-mail Address, single, optional)

The E-mail address of the developer mailing list.

Example: sample-dev at doe.com

2.5.12. Users-mailinglist

(E-mail Address, single, optional)

The E-mail address of the users mailing list.

Example: sample-users at doe.com

2.5.13. Issue-tracker

(URL, single, optional)

A URL to the issue tracker of the package, where new issues/bugs/requests can
be reported.

Example: http://www.zope.org/trackers/sample/

2.5.14. Repository-location

(URL, single, optional)

The URL to the repository. The URL should be usable to actually check out the

Example: svn://svn.zope.org/repos/main/sample

2.5.15. Repository-web-location

(URL, single, optional)

The URL to the repository's browsable HTML UI.

Example: http://svn.zope.org/sample

2.5.16. Certification-level

(Choice, single, optional)

Describes the certification level of the package. The value can be one of the
following five: None, listed, level1, level2, level3

Example: level1

2.5.17. Certification-date

(Date, single, optional)

The date at which the certification was received. The date should be in the
format ``yyyy-mm-dd``.

Example: 2006-02-28

2.5.18. Metadata-Version

(Text Line, single, required)

This is the version number of this package meta-data.

Example: 1.1

2.6. Package Certification Data

In addition to the package's meta-information, certified packages must also
track their certification history. This section describes to information that
needs to be stored.

The following data description is known as the *Package Certification Data
Version 1.0*.

Certifications can be granted and revoked. Those activities are known as
*Certification Actions*. You can also receive a warning. For each
certification action the following pieces of information must be recorded. The
same sub-section layout as in section 2.5. applies.

2.6.1. Action

(Choice, single, required)

The action describes whether a certification was granted or revoked. Upon
violations (as defined in section 2.8), a certification manager can also issue
a warning.

Allowed Values: grant, revoke, warn
Example: granted

2.6.2. Source-level

(Choice, single, required)

This field describes the original certification level before this
certification action was executed.

Allowed Values: none, listed, level1, level2, level3
Example: listed

2.6.3. Target-level

(Choice, single, required)

This field describes the final certification level after this
certification action was executed.

Allowed Values: none, listed, level1, level2, level3
Example: level1

2.6.4. Date

(Date, single, required)

The date on which the certification action was executed. The field should be
of the format ``yyyy-mm-dd``.

Example: 2006-02-11

2.6.5. Certification-manager

(Text Line, single, required)

This field lists the person that executed the certification action. It is the
full name and E-mail address of the person.

Example: John Doe <john at doe.com>


(Text, single, optional)

This field can contain arbitrary comments about the certification action.

Example: The authors of the Sample package have cooperated well by swiftly
         providing all necessary information required for the certification to
         be granted.

2.7. Package Release Data

Finally, all the releases of certified packages *must* be tracked. This
section describes the data that must be recorded for each release. The same
sub-section layout as in section 2.5. applies.

The following data description is known as the *Package Release Data Version

2.7.1. Name

(Text Line, single, required)

The name under which the package will be known for this release. This field
*may* be equivalent to the name field described in section 2.5.1.

Example: Sample Package

2.7.2. Version

(Text Line, single, required)

This field describes the version number of the release.

Example: 0.9.0b2

2.7.3. Codename

(Text Line, single, optional)

The code name of the release.

Example: CoolName

2.7.4. Date

(Date, single, required)

The date on which the release was made. The date should be in the form

Example: 2006-02-01

2.7.5. Certification

(Choice, single, required)

The certification level of the package at the date of the release.

Allowed Values: none, listed, level1, level2, level3
Example: level1

2.7.6. Package

(URL, single, required)

The URL to the installation package file.

Example: http://www.zope.org/Products/SamplePackage/SamplePackage-0.9.0.tgz

2.7.7. Source

(URL, single, optional)

The URL to the repository location. It should be possible to use this URL to
make a checkout.

Example: svn://svn.zope.org/zf.sample/tags/0.9.0b2

2.7.8. Dependency

(Text Line, multiple, required)

A dependency to another package. The dependency must contain the full name of
the package and the version number. One entry of this field *must* be
specified for each dependency.

Example: Zope 3.3

2.7.9. Announcement

(URL, single, optional)

A link to the announcement of the release.

Example: http://www.zope.org/Products/SamplePackage090Released

2.7.10. Release-manager

(Text Line, single, required)

The full name and E-mail address of the release manager. Both sub-fields
should be separately be available.

Example: John Doe <john at doe.com>

2.7.11. Press-contact

(Text Line, single, required)

The full name and E-mail address of the press contact. Both sub-fields
should be separately be available.

Example: John Doe <john at doe.com>

2.8. The Process

The main purpose of this section is to define the workflow that a package
undergoes to change its certification level within the ZSCP. A secondary goal
is to provide a roadmap for packages to move upstream into the Zope or even
Python core, if applicable. With this in mind, it should be easy for the Zope
users to find and discover packages, including their meta, certification and
release data. Also, receiving a certification level should be perceived as
reward for the hard work being done; an accomplishment the package authors
should be proud of and be able to market it accordingly.

The certification process is conducted by the Zope Foundation with the tight
collaboration of the "core developers". For lack of any other definition, core
developers are defined as developers regularly contributing to the Zope core
components. They are often informally identified by the community. The
developers conducting the certifications are known as the *certification

As defined in section 2.3., the ZSCP defines four distinct package
certification levels. Achieving the first status of being a listed package is
an automated process. Once the authors fulfill the package layout guidelines,
have provided all required package meta-data and are hooked into the automated
test runner, then listed package status will be granted to them from the

For the other three certification levels, a certification manager *must* grant
the certification level. The authors of a package have to demonstrate that
they have fulfilled the requirements for the desired level. The fulfillment of
the requirements is checked automatically via some tools, like the automated
test runner and coverage checker, and by inspection of the certification

Both, the requirements and process, are developed in a way that it
should be also simple and fast to receive certification level 1 and level
2. The turn-around time of a request for being granted a certification level 1
or level 2 should be about 1 day.

The certification of level 3 will usually take some more time, since it
requires the certification manager to inspect the code in much more
detail. However, the certification time should not exceed a couple of weeks.

Overall, it is very important for the process to have as little overhead as
possible and make the certification process a quick, easy and fun experience.

When packages are not maintained anymore, they may lose their
certification. If a package is not updated for a given Zope release cycle
once, it receives a warning. If the package is not updated for a second
release cycle in a row, it will lose its certification and will be demoted to
the next appropriate level. This will commonly mean that it becomes a "listed"
package again. The exception is, of course, when a package has no changes
since the last version. In those cases it is simply enough to verify that the
package still works and to make an entry in the ``CHANGES.txt`` file to that

When any of the requirements listed in this document change, then the packages
have one release cycle to upgrade to the new requirements. After one release
cycle, the package receives a warning. If the requirements are not upgraded
for another release cycle, the package will loose its certification and will
be demoted to the next appropriate level.

While certified packages have to fulfill the requirements of the quality
metrics, in return there will also be some technical benefits. Packages that
are part of the ZSCP will be automatically tested, have coverage reports
created, and be listed on the ZSCP Web site.

There is *no* fee associated with the certification. One of the goals of the
program is to encourage developers to write better code and provide them with
ways to measure it. The certification is a way of saying "thank you". And for
the community it is overall better to have as many certified packages as

3. The Common Repository

This section describes an open community repository that implements the ZSCP

3.1. Definition

The Common Repository is a Zope Foundation SVN repository for third-party Zope
packages, which are useful for a wide variety of applications, but that do not
fit into the Zope core distribution. Common examples for those packages
include advanced Javascript-based widgets, alternative templating systems,
specific content types, etc.

The existing ``svn://svn.zope.org/repos/main`` will serve as the Common
Repository. Every package in the common repository *must* conform at least to
the layout as described in section 3.2. If a package wishes to participate in
the ZSCP, then it must also conform to the program's process. The
implementation details of the ZSCP process are provided in the sections below.

Unless otherwise stated, certified packages will automatically be released
with every new Zope release. This, on the other hand, will greatly simplify
the dependency tree for Common Repository based packages.

3.2. Layout

Packages in the Common Repository *must* have the following layout:

      ... setup files ...
            ... code ...
    zscp/ [optional]
      PUBLICATION.cfg [optional]
      CERTIFICATIONS.xml [optional]
      RELEASES.xml [optional]

This layout, with exception of the ``zscp/`` directory, follows the common
layout guidelines of SVN and Python. The optional ``zscp/`` directory contains
all the information to satisfy the ZSCP's package data requirements. The key
file is ``ZSCP.cfg``, which contains a reference to other files containing the
necessary data.

The format of the ``ZSCP.cfg`` file is as follows::


The value for each field, ``publication``, ``certifications``, and
``releases`` is a relative path or URL to the corresponding file. The formats
for those files is defined in section 3.3.

The ``zscp/`` directory and the ``ZSCP.cfg`` file should be auto-generated
using the ZSCP homepage. The goal of the ZSCP configuration file is to
disconnect the concern of the package manager with that of the certification
manager. In other words, the package manager should *never* be concerned with
the maintenance of the of the ZSCP certification and data in the repository.

While other repository layouts were originally considered, the layout above
has several advantages. First of all, it keeps the hierarchy of the repository
relatively flat; it is really just one level deep. Python developers tend to
like that. The naming of packages as ``<NAMESPACE>.<PACKAGE>`` is already used
in the zope.org repository now and works well.

However, a package in the Common Repository is *not* required to apply the ZSCP
process. This will allow for experimental and non-generic packages to reside
in the Common Repository as well.

Since it is not the goal of the Common Repository to assimilate all projects,
one can choose whatever namespace desired for a package. There are a only a
few rules:

1. Every package *must* be located in a namespace.

2. Packages from the same developer/institution should have the same
   namespace. For example, Zope Corporation always uses ``zc``.

3. The ``zope`` namespace is reserved for Zope 3 core components.

4. The default namespace for one-time package developers to use is ``zf`` --
   short for Zope Foundation.

The Common Repository is *not* a replacement for other high-level repositories
like Plone's or ECM's. It does not aim at assimilating everything in the wider
Zope community. It is merely a place for high-quality packages that are
supported by the Zope development team.

Code in the Common Repository *must* also use the license stated in
section 3.5 and developers *must* sign the contributor agreement. The
agreement is necessary to ensure that contributions originated from the
contributing developer.

A final goal of the Common Repository is to ease the upstream movement of
packages. It should be easy to promote a package to the Zope 3 core or even to
the Python standard library. Since all packages in the Common Repository have
a license that can be changed by the Zope Foundation and developers have
signed contributor agreements, packages can be easily moved into the Zope 3
and Python core.

3.3. Package Publication, Certification, and Release Data

The package data that must be available for all packages participating in the
ZSCP is contained in three data files. The format of each file is described

3.3.1. The Publication Data File

The publication file is a simple meta-data file in the Internet Message Format
(RFC 2822). This format allows simple key-value pair assignments that can occur
multiple times. It is also the format used for HTTP headers.

The keys in the publication files must correspond to the names of the
sub-sections in section 2.5.

Zope 3 has already successfully used this format to provide meta-data to the
Python Package Index (PyPI).

The publication data file is commonly named ``PUBLICATION.cfg``.

3.3.2. The Certification Data File

The certification data file is a simple XML file. The root element is
``certifications`` with ``certification`` sub-elements. Each field listed in
section 2.6 is a sub-element of ``certification``.

The certification data file is commonly named ``CERTIFICATIONS.xml``.

This file is auto-generated by the ZSCP Web site.


        <name>Jane Doe</name>
        <email>jane at doe.com</e-mail>
        <name>Jane Doe</name>
        <email>jane at doe.com</e-mail>

3.3.3. The Release Data File

The release data file is a simple XML file. The root element is
``<releases>`` with ``<release>`` sub-elements. Each field listed in
section 2.7 is a sub-element of ``<release>``.

The release data file is commonly named ``RELEASES.xml``.

If the package is part of ZSCP, then entries will be added automatically for
automated releases at the end of a Zope release cycle.


      <name>Sample Package</name>
        <dependency>Zope 3.2</dependency>
        <dependency>zope.otherpackage 1.2</dependency>
        <name>John Doe</name>
        <email>john at doe.com</e-mail>
        <name>John Doe</name>
        <email>john at doe.com</e-mail>

3.4. Quality Assurance

The goal of the Common Repository and its supporting software stack is to
automate as many quality assurance tasks as possible. The following
sub-section lists such tools. The full development of those tools is expected
to be a long-term process.

3.4.1. Automated Test Runner

The trunks of the packages in the Common Repository are generally expected to
pass all tests. The zope.org buildbot setup will be used to verify all tests
of a package after each checkin. Any test failures will be
reported. Furthermore, packages should not contain any deprecation
warnings. Since instantaneous updating is not practical, a period of 4 weeks
(or, if shorter, until the first beta of the next Zope 3 release) will be
granted to remove any deprecation warnings, due to refactoring.

- The buildbot setup is in place.
- A buildout system needs to be developed to describe to buildbot how to build
  the package environment to run the tests.

3.4.2. Test Coverage Reports

The test runner provides a neat option "--coverage" that reports the lines
that were not executed during the testing period. The test coverage will be
run regularly, probably as part of the buildbot test runs. Whenever a package
does not fulfill its required coverage quota (as defined by the quality
metric), a message will be sent to the mailing list. Also, an HTML version of
the coverage report will be made available.

*Note:* The current version of the coverage tool does not work very
well. Marius Gedminas of SchoolTool has reimplemented the option for the
custom SchoolTool test runner, which works much better; he needs to port
his implementation. He also developed a high-level script to report the
coverage via an HTML site.

See http://source.schooltool.org/coverage/

- The concept of test coverage exists.
- The tool to convert coverage reports to an HTML page exists.
- The better coverage implementation of SchoolTool needs to be ported.

3.4.3. Publication Data Verification

Since the publication data is central to providing sufficient information
about a package, it will be necessary for a tool to regularly check the
completeness of the file and verify any external links.

- This tool has to be written, but should not be too hard, since a parser and
  writer for the publication data must be developed for the ZSCP Web site

3.4.4. Dependency Checker

A dependency checker will ensure that all used packages and modules are listed
in the ``DEPENDENCIES.cfg`` file. While this is not a versioned dependency
check, it allows to detect unwanted or unknown dependencies. If an unlisted
dependency is found, a message to the mailing list will be sent.

- This tool does not exist yet, though a dependency detection tool is already
  available. Its code could be used to implement this tool.

3.4.5. Nightly TAR-ball Testing

A nightly cron job could generate a TAR-ball of the package and check whether
it is functioning correctly.

SchoolTool has already deployed such a tool successfully.

- While a "prototype" exists, it would be somewhat difficult to produce an
  environment in which the package could be properly run.

3.4.6. Coding Style Verification

While coding style verification can never be fully tested, there are some
elements that can be checked:

- Has file called ``interfaces.py``
- Has ``tests.py`` file or ``tests/`` directory
- Class names start with upper letter and have no underscore
- Has a ``README.txt`` file

- Such a tool is not implemented yet.

3.4.7. Migration Script Testing

Often data migration scripts are written without fully testing them in an
involved test environment. The most effective way to test a migration script
is to actually store an old version of the database, apply the migration
script and check whether the data was converted correctly. Fortunately, this
type of testing does not require any new technology and simply needs to be

- The documentation to writing those type of tests needs to be written.

3.5. Coding Style Guidelines

In general the Zope 3 coding style guidelines apply.


The following additional guidelines are provided.

* State of Code

  At any given time, the trunk of a package *must* be beta quality, if the
  package is scheduled for a release within the Zope release cycle. That means
  the code should be always beta quality, pass all tests and have complete
  documentation. Code in branches do not have to fulfill any of those

* Documentation

  There needs to be at least one ``README.txt`` file explaining the generic
  use of the code. If other tests are provided, it is not necessary to cover
  all corner cases. However, it will be preferred that a set of text
  documentation files will cover all of the functionality, including all
  corner cases. If those details are too much for a single README.txt file,
  the developer should not hesitate to create multiple text files, making
  sure that they are linked from the ``README.txt`` file. All text files
  *must* be doctests to ensure that the information is up-to-date.

* Backward-Compatibility

  The package *must* provide backward-compatibility for two following major
  releases. Concretely, if a feature is deprecated in X.Y, then it must be
  supported for X.Y and X.(Y+1). The backward-compatibility can be removed
  in X.(Y+2). By backward-compatibility it is meant that the old API still
  has to work as before, but a deprecation warning is raised, if the old API
  is used.

* Migration

  Once one stable release has been made, generation scripts *must* be
  provided to upgrade to the next release, if the package stores any data in
  the ZODB. Zope 3 provides all the necessary facilities to do so.

  Since migration/generation scripts are code like any other code, the
  question on testing generation scripts comes to mind. Testing migration
  scripts can be possible, if the structure of the script is
  well-designed. Thus migration/generation scripts should be tested.

* Dependencies

  All dependencies of a package must be listed in a ``DEPENDENCIES.cfg``
  file. The dependencies must be listed as a Python path. There is one
  dependency per line.

3.6. Releases

By default, packages in the Common Repository will adopt the same release
schedule as Zope. The Zope development team releases two major releases a
year, one in May and one in November.

A positive side effect of this rule is that the dependencies on Common
Repository packages should be pretty simple. This model has worked great for
the KDE community, which always distributes a large set of their libraries and
programs at the same time.

However, packages may also choose their own release schedule. In this case
dependencies must be carefully stated in the release data file.

3.7. License

The license of the repository is probably the most sensitive issue. The Plone
community has stated several times the need to protect their core values using
the GPL. However, in order to maximize cooperation with other projects, the
Plone community also agrees to develop generic packages under different
licenses. Other parties usually use the ZPL or a BSD-like license.

Thus it is proposed to place all the packages in the Zope 3 Common Repository
under the ZPL.

There has been an alternative argument and proposal concerning licenses. One
of the goals of Zope 3 is to become a better citizen of the Python community,
in other words, Zope wants to be more Pythonic. From a Python developer's point
of view, the ZPL is yet another reminder that Zope has special rules. It has
thus been proposed to use the Python license.

Another issue that has surfaced frequently in the past was the inclusion of
third-party software; this especially applies to Javascript libraries. If a
third-party software is included in the repository as part of a package, the
package *must* contain a ``LICENSES.txt`` file that lists all the applicable
licenses with a reference to the code they apply to. The release manager
and/or a member of the "checkin police" (to be determined) *must* be notified
of such inclusion, so that the references can be verified. Failure to do so
can result in loss of checkin privileges and/or removal of the package. While
this policy might sound very demanding at first sight, it is simply a
necessary measure to protect the Zope community legally.

3.8. An Example

(informal voice)

In the last weeks, I have frequently used an example to illustrate the
process. One very common functionality that is needed for many types of Web
applications is the "search". Depending on the software stack one is using,
the actual "search" implementation might be quite different. However, there is
some value in defining a simple, but generic search API. Based on this API a
package would provide a nice set of UI components that could be used by anyone
implementing the search API.

Since such a package (possibly including a generic sample implementation)
would be very useful for a wide variety of people, it would be added to the
Common Repository. After some initial setup, the package will have the
"listed" ZSCP status. This should open up the visibility a lot and attract
people from sub-communities, like Plone, tiks and Z3ECM.

Since people from other Zope communities provide a very large skillset, the
community effect is used to improve the API and some initial implementations
are done against the API. At this stage the package would apply for Level 1

As the API matures, specific projects like Plone would then provide specific
implementations of this search API and maintain this code in their repository,
since (a) the code would not be very useful for other projects and (b) the
additional code provides specific value that can be protected. This process
also naturally adds support and documentation to the package, making it
possible to apply for Level 2 certification.

Once the package is mature and the sub-projects have successfully deployed it,
the package will receive the Level 3 certification. While this process may
take a year or longer to complete, it ensures that the API of the search
package is truly useful and provides benefit to the intended audience.

A1. Questions and Answers

Why would you want your package in the Common Repository?

Placing your package in the Common Repository (like the collective in other
communities) will ensure a certain exposure of the code to others. If your
package will be certified, then other people will dedicate time to keep up the
compatibility and quality of the package. Further, you can use the
certification as a way to market your software and your skills. It is also
*your* personal way you can contribute back to the community.

Is the proposal too formal? Is the entry bar too high?

Some people might argue that the process is too formal and that the demotion
clause for certified packages will cause no packages being certified. I
do not think that will be the case. There will always be a set of packages
that many people will rely on (such as RDB adapters, LDAP adapter,
authentication plugins) and where the community has a vested interest in
maintaining them. Also, I think there is a general desire in the wider Zope
community to have quality packages; this proposal provides a roadmap for
developers to produce those high-quality packages.

How does this fit into the Cubed effort?

First a definition of "Cubed": Cubed is an effort by the Plone developers to
develop generic Zope 3 components that are primarily applicable to Plone
(integrated via Five for now), but are also usable by a wider
audience. The ultimate goal is to eventually provide a migration path of Plone
from the Zope 2 to the Zope 3 platform.

The Cubed effort splits into the generic packages and the specific Plone
configuration and user experience. While the generic packages should be
developed in the proposed Common Repository, the configuration and user
interface should be maintained by the Plone Foundation under their governance.

Will the repository present a full-functioning application, like a CMS?

No, the purpose of the repository is to be a *collection of components* that
is useful for a wider variety of applications. Applications should be
developed, maintained and governed outside this repository. For example, Plone
is developed by the Plone Foundation on plone.org and the Tiks CMS by
Projekt01 on tiks.org. However, those applications may apply for certification.

Will the Zope Foundation and/or the Zope core developers have the bandwidth to
process certification requests in a timely manner?

One big goal of the quality metrics section is to identify a set of
quantifiable items that can be easily verified using an automated
process. Thus the overhead for the core developers should be minimized. Also,
an efficient Web site for the process should allow certification managers to
quickly provide the certification. Overall, certifying a package should become
as common of a task as making releases or even writing documentation.

For such a process it seems to be useful to have an issue tracker, special
mailing lists and/or an advanced buildbot setup. Why are those technologies
not addressed in the proposal?

This proposal is *not* about technical solutions. It is about defining a
process and laying the implementation of this process via a community
repository. The purpose of the proposal is to establish an initial set of
guidelines/rules and not to discuss the technical implementation.

Why are dependencies not addressed in more detail?

Currently, we simply do not have any system in place that could sensibly
handle version requirements. However, several systems are currently being
built. The goal of this proposal is not to invent yet another version
dependency system. Thus the issue is deferred until the Zope community decides
on a system to use.

Are we going to certify core packages that are also seperate projects?

Yes, I imagine that it will be generally easier to certify those
packages. Also, having them certified separately makes it easier to amrket
their certification.

A2. Glossary

Certification Action
  A change in certification level. Currently there are two actions, granting
  and revoking.

Certification Manager
  A person that executes the certification process.

Common Repository
  A community repository governed by Zope Foundation for the development of
  generic Zope packages.

Package Certification Data
  Data that describes the certification history of the package.

Package Meta-Data
  Data that describes the package itself. It is also known as publication data.

Package Release Data
  Data describing all releases since entering the ZSCP process.

Quality Metric
  A quantifiable item to measure the quality of a package.

Zope Community Process
  A set of methods used to develop Zope add-on packages and itself, such as
  sprints, proposals and testing.

Zope Software Certification Program (ZSCP)
  A process conducted by the Zope Foundation and core developers to certify
  package's quality.

ZSCP Level X Certified
  A certification level that the ZSCP grants to a package.

ZSCP Listed
  A pre-certification level that lists a package on the ZSCP homepage.

A3. Pre-proposal Committee

Before I made the proposal public, I chose a few people to comment on the
draft. I tried to choose people from the main interest groups:

* Julien Anguenot (Nuxeo, Z3ECM Developer)
* Jodok Batlogg (Plone Foundation, Plone Developer)
* Paul Everitt (Plone Foundation, ZEA)
* Martijn Faassen (Infrae, hurry Developer)
* Roger Ineichen (Projekt01, tiks Developer)
* Whit Morriss (Plone Foundation, Plone Developer)
* Gary Poster (Zope Corporation, Zope 3 Developer)

(Sorted alphabetically by surname.)

Later I enlarged this group of people to get more feedback. Those people were
more randomly chosen:

* Nate Aune (Plone Developer)
* Rocky Burt (Plone Developer)
* Sidnei DeSilva (Enfold Systems, Plone Developer)
* Russ Ferriday (Plone Developer)
* Marius Gedminas (SchoolTool, POV, Zope 3 Developer)
* Tom Hoffman (SchoolTool)
* Dominik Huber (tiks Developer)
* Michael Kerrin (Zope 3 Developer)
* Rob Page (Zope Corporation)
* Alan Runyan (Enfold Systems, Plone Foundation)
* Philipp von Weitershausen (Zope 3 Developer, Five Developer)
* Benji York (Zope Corporation, Zope 3 Developer)

(Sorted alphabetically by surname.)

A4. Changes

Version 0.7
- Added a third certification action: warn
- Got test coverage requirements right; it should be greater than
- Made a note that for small packages a Web-repository is enough to put
  docuemntation online.
- Added Q&A about certifying core packages that have separate releases
- Added a note to level 1 description, that this level is generally good
  enough for the core.
- Added a note that package information is compatible with PyPI data.
- Write some more about the marketing effect.

Version 0.6
- Complete rewrite of the proposal to address the following issues:
  * naming of process and certification levels.
  * concern of not separating the process from the repository (implementation)
  * being random
  * not clearly specifying the quality requirements
- Added Glossary
- Expanded Pre-proposal committee list

Version 0.5
- Explain what ``zf`` stands for.
- Correct facts about SchoolTool's coverage feature.
- Explain that not all packages in the Common Repository must apply for the
  ZAP process.
- Applied various typo and grammar/spelling fixes.
- Changed date format.
- Made a note about having no fee for the certification.
- Added QA section for BBB.
- Added questions and answers.
- Simplified ZAP format a little bit.
- Clarified the term "Cubed".

Version 0.4
- Formalized writing style.
- Incorporated Gary's ideas of the Zope Accountability Program. That meant
  rewriting the entire "Process" and most of the "Common Repository" section.

Version 0.3
- Moved ``z3ecm`` project to correct location after renaming
- Added note about packages that have no changes in a new version, but are
- Added note about automated releases.
- Added more ideas about namespaces.
- Added text about alternative Python license and how to deal with third-party
  included code.
- Added CHANGES section.
- Commented that test coverage reports will be run regularly.
- Added a comment on testing migration scripts.
- Answered a question about the fear of the repository being too formal.
- Collapsed back to one repository structure suggestion and reasoned why it is
  the best approach.

Version 0.2
- Alternative package structure
- Additional answered question about not hosting full applications
- Added Dependencies section

Version 0.1
- Initial draft

More information about the Zope3-dev mailing list