=head1 NAME

internals - Some internal information about the WE_Framework

=head1 DESCRIPTION

=head2 ObjDB

The object metadata database is implemented as an MLDBM database.
Therefore, the contents of the database can either be looked in with
the C<show_db> program or with the C<dump> script (the latter is
included with C<WE_Framework>).

The objects in the object database are array references of four
elements:

=over 4

=item *

The first element contains a hash reference to the attributes of the
object. The current object is the current work version (if there are
multiple versions).

=item *

The second element contains an array reference to the IDs of the
children of this object. Of course, only folder objects can have
children.

=item *

The third element contains an array reference to the IDs of the
parents of this object. Multiple parents are possible; the first
parent ID is handled as the "main" parent (e.g. as the default parent
if no one is specified in methods like C<move>).

The root object should not have any parents. Also, version objects are
stored as normal objects in the database, but have no parents.

=item *

The fourth element contains an array reference to the IDs of the
versions of this object.

=back

Here's an example:

    [ {'Title' => 'A Folder',
       'Id'    => '26', ...
      },   # object
      [],  # children (here: no children)
      [4], # parents
      []   # versions (here: no versions)
    ]

There are two special keys in the database:

=over 4

=item _root_object

The value is the ID of the root object of the database (usually a
WE::Obj::Site or WE::Obj::Sites).

=item _next_id

The value is the next free ID for new objects.

=back

=head2 ContentDB

The current implementation of the content database is simply files in
a filesystem. The file names are constructed of the corresponfing
object id and the right content-type extension. If there is no
content-type, then the extension ".bin" is used. For example, the
object with the id 12 and the content-type C<text/html> is "12.html".

=head1 AUTHOR

Slaven Rezic <slaven@rezic.de>

=head1 SEE ALSO

WE::DB(3).