=head1 NAME

Geo::EOP - Earth Observation Products EOP (formely HMA)

=head1 INHERITANCE

 Geo::EOP
   is a XML::Compile::Cache

=head1 SYNOPSIS

 use Geo::EOP ':eop1.1';

 my $eop = Geo::EOP->new('READER', version => '1.1');

 # see XML::Compile::Cache on how to use readers and writers
 my $data = $eop->reader("gml:GridCoverage")->($xmlmsg);
 my $xml  = $eop->writer($sometype)->($doc, $perldata);

 # or without help of the cache, XML::Compile::Schema
 my $r    = $gml->compile(READER => $sometype);
 my $data = $r->($xml);

 # huge overview on all defined elements
 $gml->printIndex;

=head1 DESCRIPTION

Provides access to the EOP definitions specified in XML, which is
based on GML.  Up to version 1.0, these schemas where named 'HMA'
(Heterogeneous EO Missions Accessibility), and the development is
still part of these ESA efforts for standardization.

BE WARNED that HMA1.0 and EOP 1.1/1.2 are only using a B<subset> of GML
version 3.1.1, due to problems with some software tools.  This limitation
will probably be removed in 1.3 (or whatever the next version will
be named).  EOP version 1.2-beta as defined here, is expected to become
the final 1.2 in December 2008, with only minor modifications.

The first releases of this module will not powerful, but hopefully
people contribute.  For instance, an example conversion script between
various versions is very welcome!  It would be nice to help each other.
I will clean-up the implementation, to make it publishable, but do not
have the knowledge about what is needed.

=head1 METHODS

=head2 Constructors

Geo::EOP-E<gt>B<new>('READER'|'WRITER'|'RW', OPTIONS)

=over 4

 Option          --Default
 allow_undeclared  <true>
 prefixes          undef
 units             <none>
 version           <required>

. allow_undeclared => BOOLEAN

=over 4

In the optimal case, all types used in your application are declared
during the initiation phase of your program.  This will make it easy
to write a fast daemon application, or transform your program into a
daemon later.  So: "false" would be a good setting.  However, on the moment,
the developer of this module has no idea which types people will use.
Please help me with the specs!

=back

. prefixes => ARRAY|HASH

=over 4

Prefix abbreviations, to be used by cache object.  Which prefixes are
defined depends on the schema version.

=back

. units => HASH

=over 4

See L</Units>.  Only if you specify your preference in units of measurement,
some automatic translations will be performed.

=back

. version => VERSION|NAMESPACE

=over 4

Only used when the object is created directly from this base-class.  It
determines which EOP syntax is to be used.  Can be a VERSION like "1.1"
or a NAMESPACE URI like 'NS_EOP_11'.

=back

=back

=head2 Accessors

$obj-E<gt>B<direction>

=over 4

Returns 'READER', 'WRITER', or 'RW'.

=back

$obj-E<gt>B<printIndex>([FILEHANDLE], OPTIONS)

=over 4

List all the elements which can be produced with the schema.  By default,
this only shows the elements and excludes the abstract elements from
the list.  The selected FILEHANDLE is the default to print to.

=back

$obj-E<gt>B<version>

=over 4

EOP/HMA version, for instance '1.0'.

=back

=head1 DETAILS

=head2 Units

GML is careful about its units, which is nice but verbose.
Therefore, this module gives you a way to set your preferences.
The reader will simplify the structure, re-calculating the values
found into the units of measure you prefer, according to UCUM
(F<http://aurora.regenstrief.org/ucum>)

  my $eop = Geo::EOP->new(...
     , units => { distance => 'm'
                , angle    => 'deg' }
     );

Available conversions:

=over 4

=item angle 'deg'|'rad'

Will be applied to all AngleType elements

=item distance 'm'

Will be applied to all MeasureType elements

=item percentage '%'|'float'

Will be applied to all elements with a name ending on "Percentage".
I am not sure about the C<float>... cannot find the uom name.

=back

=head1 SEE ALSO

This module is part of Geo-EOP distribution version 0.10,
built on July 08, 2008. Website: F<http://perl.overmeer.net/geo/>
All modules in this suite:
L</Geo::GML>,
L</Geo::ISO19139>,
L</Geo::EOP>,
L</Geo::Point>,
L</Geo::Proj4>,
L</Geo::WKT>, and
L</Math::Polygon>.

Please post questions or ideas to
F<http://geo-perl@list.hut.fi|the Geo-Perl mailinglist>

=head1 COPYRIGHTS

=head2 License of the CODE

Copyrights of the perl code and the related documentation by
2008 by Mark Overmeer. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://www.perl.com/perl/misc/Artistic.html>

=head2 License of the SCHEMAS

The included schemas are copyrighted by the Open Geospatial Consortium, Inc.
They are unmodified copied from the files at F<http://schemas.opengis.net>.
Read OGCs disclaimer and copyright statements on documentation and software
at F<http://www.opengeospatial.org/ogc/legal>.  The license text is also
included in this CPAN distribution.