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Meta_1_1.pod

=for :stopwords Ingy READMEs WTF licensure

=head1 NAME

CPAN::Meta::History::Meta_1_1 - Version 1.1 metadata specification for META.yml

=head1 PREFACE

This is a historical copy of the version 1.1 specification for F<META.yml>
files, copyright by Ken Williams and licensed under the same terms as Perl
itself.

Modifications from the original:

=over

=item *

Conversion from the original HTML to POD format

=item *

Include list of valid licenses from L<Module::Build> 0.18 rather than
linking to the module, with minor updates to text and links to reflect
versions at the time of publication.

=item *

Fixed some dead links to point to active resources.

=back

=head1 DESCRIPTION

This document describes version 1.1 of the F<META.yml> specification.

The F<META.yml> file describes important properties of contributed Perl
distributions such as the ones found on L<CPAN|http://www.cpan.org>.  It is
typically created by tools like L<Module::Build> and L<ExtUtils::MakeMaker>.

The fields in the F<META.yml> file are meant to be helpful to people
maintaining module collections (like CPAN), for people writing
installation tools (like L<CPAN> or L<CPANPLUS>), or just people who want to
know some stuff about a distribution before downloading it and starting to
install it.

=head1 Format

F<META.yml> files are written in the L<YAML|http://www.yaml.org/> format.  The
reasons we chose YAML instead of, say, XML or Data::Dumper are discussed in
L<this thread|http://www.nntp.perl.org/group/perl.makemaker/2002/04/msg406.html>
on the MakeMaker mailing list.

The first line of a F<META.yml> file should be a valid
L<YAML document header|http://yaml.org/spec/history/2002-10-31.html#syntax-document>
like C<"--- #YAML:1.0">

=head1 Fields

The rest of the META.yml file is one big YAML
L<mapping|http://yaml.org/spec/history/2002-10-31.html#syntax-mapping>,
whose keys are described here.

=over 4

=item name

Example: C<Module-Build>

The name of the distribution.  Often created by taking the "main
module" in the distribution and changing "::" to "-".  Sometimes it's
completely different, however, as in the case of the
L<libwww-perl|http://search.cpan.org/author/GAAS/libwww-perl/> distribution.

=item version

Example: C<0.16>

The version of the distribution to which the META.yml file refers.
This is a mandatory field.

The version is essentially an arbitrary string, but I<must> be
only ASCII characters, and I<strongly should> be of the format
integer-dot-digit-digit, i.e. C<25.57>, optionally followed by
underscore-digit-digit, i.e. C<25.57_04>.

The standard tools that deal with module distribution (PAUSE, CPAN,
etc.) form an identifier for each distribution by joining the 'name'
and 'version' attributes with a dash (C<->) character.  Tools
who are prepared to deal with distributions that have no version
numbers generally omit the dash as well.

=item license

Example: C<perl>

a descriptive term for the licenses ... not authoritative, but must
be consistent with licensure statements in the READMEs, documentation, etc.

The license under which this distribution may be used and
redistributed.

Must be one of the following licenses:

=over 4

=item perl

The distribution may be copied and redistributed under the same terms as perl
itself (this is by far the most common licensing option for modules on CPAN).
This is a dual license, in which the user may choose between either the GPL
version 1 or the Artistic version 1 license.

=item gpl

The distribution is distributed under the terms of the GNU General Public
License version 2 (L<http://opensource.org/licenses/GPL-2.0>).

=item lgpl

The distribution is distributed under the terms of the GNU Lesser General
Public License version 2 (L<http://opensource.org/licenses/LGPL-2.1>).

=item artistic

The distribution is licensed under the Artistic License version 1, as specified
by the Artistic file in the standard perl distribution
(L<http://opensource.org/licenses/Artistic-Perl-1.0>).

=item bsd

The distribution is licensed under the BSD 3-Clause License
(L<http://opensource.org/licenses/BSD-3-Clause>).

=item open_source

The distribution is licensed under some other Open Source Initiative-approved
license listed at L<http://www.opensource.org/licenses/>.

=item unrestricted

The distribution is licensed under a license that is B<not> approved by
L<www.opensource.org|http://www.opensource.org/> but that allows distribution
without restrictions.

=item restrictive

The distribution may not be redistributed without special permission from the
author and/or copyright holder.

=back

=item license_uri

This should contain a URI where the exact terms of the license may be found.

(change "unrestricted" to "redistributable"?)

=item distribution_type

Example: C<module>

What kind of stuff is contained in this distribution.  Most things on
CPAN are C<module>s (which can also mean a collection of
modules), but some things are C<script>s.

This field is basically meaningless, and tools (like Module::Build or
MakeMaker) will likely stop generating it in the future.

=item private

WTF is going on here?

index_ignore: any application that indexes the contents of
distributions (PAUSE, search.cpan.org) ought to ignore the items
(packages, files, directories, namespace hierarchies).

=item requires

Example:

Data::Dumper: 0
  File::Find: 1.03

A YAML L<mapping|http://yaml.org/spec/history/2002-10-31.html#syntax-mapping>
indicating the Perl modules this distribution requires for proper
operation.  The keys are the module names, and the values are version
specifications as described in the
L<documentation for Module::Build's "requires" parameter|Module::Build::API/requires>.

I<Note: the exact nature of the fancy specifications like
C<< ">= 1.2, != 1.5, < 2.0" >> is subject to
change.  Advance notice will be given here.  The simple specifications
like C<"1.2"> will not change in format.>

=item recommends

Example:

Data::Dumper: 0
  File::Find: 1.03

A YAML L<mapping|http://yaml.org/spec/history/2002-10-31.html#syntax-mapping>
indicating the Perl modules this distribution recommends for enhanced
operation.

=item build_requires

Example:

Data::Dumper: 0
  File::Find: 1.03

A YAML L<mapping|http://yaml.org/spec/history/2002-10-31.html#syntax-mapping>
indicating the Perl modules required for building and/or testing of
this distribution.  These dependencies are not required after the
module is installed.

=item conflicts

Example:

Data::Dumper: 0
  File::Find: 1.03

A YAML L<mapping|http://yaml.org/spec/history/2002-10-31.html#syntax-mapping>
indicating the Perl modules that cannot be installed while this
distribution is installed.  This is a pretty uncommon situation.

- possibly separate out test-time prereqs, complications include: can
tests be meaningfully preserved for later running?  are test-time
prereqs in addition to build-time, or exclusive?

- make official location for installed *distributions*, which can
contain tests, etc.

=item dynamic_config

Example: C<0>

A boolean flag indicating whether a F<Build.PL> or
F<Makefile.PL> (or similar) must be executed, or whether this
module can be built, tested and installed solely from consulting its
metadata file.  The main reason to set this to a true value if that
your module performs some dynamic configuration (asking questions,
sensing the environment, etc.) as part of its build/install process.

Currently L<Module::Build> doesn't actually do anything with
this flag - it's probably going to be up to higher-level tools like
L<CPAN.pm|CPAN> to do something useful with it.  It can potentially
bring lots of security, packaging, and convenience improvements.

=item generated_by

Example: C<Module::Build version 0.16>

Indicates the tool that was used to create this F<META.yml> file.  It's
good form to include both the name of the tool and its version, but
this field is essentially opaque, at least for the moment.

=back

=head2 Ingy's suggestions

=over 4

=item short_description

add as field, containing abstract, maximum 80 characters, suggested minimum 40 characters

=item description

long version of abstract, should add?

=item maturity

alpha, beta, gamma, mature, stable

=item author_id, owner_id

=item categorization, keyword, chapter_id

=item URL for further information

could default to search.cpan.org on PAUSE

=item namespaces

can be specified for single elements by prepending
dotted-form, i.e. "com.example.my_application.my_property".  Default
namespace for META.yml is probably "org.cpan.meta_author" or
something.  Precedent for this is Apple's Carbon namespaces, I think.

=back

=head1 History

=over 4

=item *

B<March 14, 2003> (Pi day) - created version 1.0 of this document.

=item *

B<May 8, 2003> - added the "dynamic_config" field, which was missing from the
initial version.

=back

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