# Below is a documentation.

=head1 NAME

XML::Directory - returns a content of directory as XML.

=head1 SYNOPSIS

 use XML::Directory::String;
 $dir = XML::Directory::String->new('/home/petr',3,10);
 $rc = $dir->parse_dir;
 @res = $dir->get_array;

or

 use XML::Directory::SAX;
 use MyHandler;
 $h = MyHandler->new();
 $e = MyErrorHandler->new();
 $dir = XML::Directory::SAX->new( Handler => $h, ErrorHandler => $e,
                                  details => 3, depth => 10);
 $rc = $dir->parse_dir('/home/petr');

=head1 DESCRIPTION

This extension provides two classes: XML::Directory::String and
XML::Directory::SAX. Their methods make it possible to set parameters
such as level of details or maximal number of nested sub-directories
and generate either string containing the resulting XML or SAX events.

The SAX generator is based on XML::SAX::Base; it's supposed to cooperate
with other XML::SAX compliant modules safely.

The original function (get_dir) is still supported via XML::Directory
base class.

 use XML::Directory(qw(get_dir));
 my @xml = get_dir('/home/petr');

=head2 METHODS COMMON TO BOTH CLASSES

Methods common to both classes are defined in the XML::Directory
base class.

=over

=item set_path

 $dir->set_path('/home/petr');

Resets path. An initial path can be set using the constructor.

=item set_details

 $dir->set_details(3);

Sets or resets level of details to be returned. Can be also set using 
the constructor. Valid values are 1, 2 or 3.

 1 = brief

 Example:

 <?xml version="1.0" encoding="utf-8"?>
 <dirtree>
   <directory name="test">
     <file name="dir2xml.pl"/>
   </directory>
 </dirtree>

 2 = normal

 Example:

 <?xml version="1.0" encoding="utf-8"?>
 <dirtree>
   <head version="0.70">
     <path>/home/petr/test</path>
     <details>2</details>
     <depth>5</depth>
   </head>
   <directory name="test" depth="0">
     <path></path>
     <modify-time epoch="998300843">Mon Aug 20 11:47:23 2001</modify-time>
     <file name="dir2xml.pl">
       <mode code="33261">rwx</mode>
       <size unit="bytes">225</size>
       <modify-time epoch="998300843">Mon Aug 20 11:47:23 2001</modify-time>
     </file>
   </directory>
 </dirtree>

 3 = verbose

 Example:

 <?xml version="1.0" encoding="utf-8"?>
 <dirtree>
   <head version="0.70">
     <path>/home/petr/test</path>
     <details>3</details>
     <depth>5</depth>
   </head>
   <directory name="test" depth="0" uid="500" gid="100">
     <path></path>
     <access-time epoch="999857485">Fri Sep  7 12:11:25 2001</access-time>
     <modify-time epoch="998300843">Mon Aug 20 11:47:23 2001</modify-time>
     <file name="dir2xml.pl" uid="500" gid="100">
       <mode code="33261">rwx</mode>
       <size unit="bytes">225</size>
       <access-time epoch="998300843">Mon Aug 20 11:47:23 2001</access-time>
        <modify-time epoch="998300843">Mon Aug 20 11:47:23 2001</modify-time>
     </file>
   </directory>
 </dirtree>

See the C<DTD> chapter for more details.

=item set_maxdepth

 $dir->set_maxdepth(5);

Sets or resets number of nested sub-directories to be parsed. Can also be
set using the constructor. 0 means that only a directory specified by path 
is parsed (no sub-directories).

=item parse_dir, parse

 $rc  = $dir->parse_dir;
 $rc  = $dir->parse;

Both methods are equivalent, the later is supported for the sake of backward
compatibility. It scans directory tree specified by path. When used from the
XML::Directory::String class instance it stores its XML representation 
in memory ($dir->{xml}) and returns a number of lines. For 
XML::Directory::SAX it generate SAX events and returns a result of
the end_document function. Parse methods of the SAX generator also accept
parameters: paths and options.

This method checks a validity of details and depth. In the event a parameter
is out of valid range, an error occurs. The same is true if the path 
specified can't be found. For the SAX generator, missing content handler is 
also treated as error.

=item get_path

 $path = $dir->get_path;

Returns current path.

=item get_details

 $details = $dir->get_details;

Returns current level of details.

=item get_maxdepth

 $maxdepth = $dir->get_maxdepth;

Returns current number of nested sub-directories.

=item pkg->order_by

 $dir->order_by($code)

Sort contents of a directory. Valid options for I<$code> are :

=over

=item df

directories, files I<default>

=item fd

files, directories

=item a

alphabetical ascending

=item z

alphabetical descending

=back

=item enable_ns;

 $dir->enable_ns; 

Enables a support for namespaces.

=item disable_ns;

 $dir->disable_ns; 

Disables a support for namespaces.

=item enable_doctype;

 $dir->enable_doctype; 

A DOCTYPE declaration will be generated.

Level of details: 1

 <!DOCTYPE dirtree PUBLIC "-//GA//DTD XML-Directory 1.0 Level1//EN"
     "http://www.gingerall.org/dtd/XML-Directory/1.0/dirtree-level1.dtd">

Level of details: 2

 <!DOCTYPE dirtree PUBLIC "-//GA//DTD XML-Directory 1.0 Level2//EN"
     "http://www.gingerall.org/dtd/XML-Directory/1.0/dirtree-level2.dtd">

Level of details: 3

 <!DOCTYPE dirtree PUBLIC "-//GA//DTD XML-Directory 1.0 Level3//EN"
     "http://www.gingerall.org/dtd/XML-Directory/1.0/dirtree-level3.dtd">

A local copy of DTD files is in the C<dtd> directory.

=item disable_doctype;

 $dir->disable_doctype; 

No DOCTYPE declaration will be generated. This is the default behavior.

=item get_ns_data;

 $ns  = $dir->get_ns_data;

Returns a hash reference with the following keys:

=over

=item enabled

either 1 or 0

=item uri

namespace URI, 'http://gingerall.org/directory/1.0/' by default 

=item prefix

namespace prefix, 'xd' by default

=back

=item encoding

 $encoding = $dir->encoding;
 $dir->encoding('utf-8');

Gets or sets an encoding of generated XML document. The encoding must be 
a string acceptable for an XML encoding declaration. The default value is
'utf-8'. The encoding doesn't apply to SAX so far.

=item enable_rdf

 $dir->enable_rdf('index.n3');

Enables a support of RDF/Notation3 meta-data. The parser looks for files with
same name as the argument of this method in each directory. If found, the file
is passed to RDF::Notation3 parser and properties of particular resources
(files or directories) are merged to resulting XML. The N3 file itself is not
listed in the XML. See http://www.w3.org/DesignIssues/Notation3.html for more 
details on RDF/Notation3.

In addition, one more element doc:Position (where doc prefix is bound to
URI namespace of http://gingerall.org/charlie-doc/1.0/) is added. This element
contains a position of the first triple with the current document as subject 
within the triple array, so that the order of files/directories can be 
controlled using the RDF/N3 file. The doc:Position element is generated even
when a document is not found in the N3 file or the N3 is not found in a 
directory; it is generated as a unique identifier handy e.g. for sorting in 
this event. Use $dir->disable_rdf to disable his feature.

If there is a property called doc:Type with value of 'document' found for 
a directory, sub-directories and files are not processed. This is a way to
emulate multiple-file documents efficiently.

If, for example, a directory contains a file named Apache.html:

 <xd:file name="Apache.html">
   <xd:mode code="33188">rw-</xd:mode>
   <xd:size unit="bytes">41913</xd:size>
   <xd:modify-time epoch="999344286">Sat Sep  1 13:38:06 2001</xd:modify-time>
 </xd:file>

Then a presence of the following Notation3 file

 @prefix dc: <http://purl.org/dc/elements/1.1/>.
 <Apache.html> 
	 dc:Title "Apache";
	 dc:Description "mod_perl Apache module".

results in:

 <xd:file name="Apache.html">
   <xd:mode code="33188">rw-</xd:mode>
   <xd:size unit="bytes">41913</xd:size>
   <xd:modify-time epoch="999344286">Sat Sep  1 13:38:06 2001</xd:modify-time>
   <doc:position>1</doc:position>
   <dc:Title>Apache</dc:Title>
   <dc:Description>mod_perl Apache module</dc:Description>
 </xd:file>

Since using RDF meta-data requires to use namespaces, this method enables
namespaces automatically. It also checks whether the RDF::Notation3 module
is installed and issues an error if not.

=item disable_rdf

 $dir->disable_rdf;

Disables RDF/N3 support.

=item error_treatment

 $et = $dir->error_treatment;
 $dir->error_treatment('warn');

Gets or sets a way errors are treated in. There are two possible
values:

=over

=item die 

The parse_dir method dies (actually croaks) on an error. Default value.

=item warn

The parse_dir methods catches the error. String generator returns an XML error
message. SAX driver throws a SAX exception and calls an error handler if
defined (otherwise it dies as for "die"). String $dir->{error} property is 
set to an error number.

Example of an error message:

 <?xml version="1.0" encoding="utf-8"?>
 <dirtree xmlns="http://gingerall.org/directory/1.0/">
 <error number="3">Path /home/petr/work/done not found!</error>
 </dirtree>

=back

=back

=head2 XML::DIRECTORY::STRING

=over

=item new

 $dir = XML::Directory->new('/home/petr',2,5);
 $dir = XML::Directory->new('/home/petr',2);
 $dir = XML::Directory->new('/home/petr');

The constructor accepts up to 3 parameters: path, details (1-3, brief or 
verbose XML) and depth (number of nested sub-directories). The last two 
parameters are optional (defaulted to 2 and 1000).

=item get_arrayref

 $res = $dir->get_arrayref;

Returns a parsed XML directory image as a reference to array (each field 
contains one line of the XML file).

=item get_array

 @res = $dir->get_array;

Returns a parsed XML directory image as an array (each field 
contains one line of the XML file).

=item get_string

 $res = $dir->get_string;

Returns a parsed XML directory image as a string.

=back

=head2 XML::DIRECTORY::SAX

=over

=item new

 $dir = XML::Directory::SAX->new( Handler => $h, ErrorHandler => $e,
                                  details => 3, depth => 10);

The constructor accepts an option hash as its only parameter. The hash keys
may include all options recognized by XML::SAX::Base (e.g. Handler, 
ErrorHandler, Source) and three options specific to XML::Directory::SAX 
(details, depth, path).

The only mandatory option is Handler, other options either have their default 
values (details=2, depth=1000, path=<current working directory>) or aren't
required.

=item other methods

Other methods include these inherited from XML::Directory (see
METHODS COMMON TO BOTH CLASSES) and those inherited from XML::SAX::Base.

Among them the following could be useful to change handlers during the parse
time safely:

=over

=item set_content_handler

 $h = new MyHandler;
 $dir->set_content_handler($h);

Sets SAX content handler.

=item set_error_handler

 $e = new MyErrorHandler;
 $dir->set_error_handler($e);

Sets SAX error handler.

=back

See XML::SAX::Base documentation for more details.

=back

=head2 ORIGINAL INTERFACE

=over

=item get_dir();

 @xml = get_dir('/home/petr',2,5);

This functions takes a path as a mandatory parameter and details and depth
as optional ones. It returns an array containing an XML representation of 
directory specified by the path. Each field of the array represents one line 
of the XML.

Optional arguments are defaulted to 2 and 1000.

=back

=head2 XML::DIRECTORY::APACHE

This is a mod_perl module that serves as an Apache interface to
XML::Directory::String. It allows to send parameters in http request and
receive a result (XML representation of a directory tree) in http
response. Errors are caught and sent as XML via http to prevent Apache error.

Parameters include:

=over

=item path

absolute path to a directory to be parsed, mandatory

The path is not send in query but as an extra path instead. This seems to
be more appropriate for this kind of parameter.

=item dets

level of details, optional

=item depth

maximal number of nested sub-directories, optional

=item ns

if set to 1, namespaces are used, optional

=back

To use this module, add a similar section to your Apache config file

 <Location /xdir>
     SetHandler perl-script
     PerlHandler XML::Directory::Apache
     PerlSendHeader On
 </Location>

and send a request to:

 http://hostname/xdir/home/petr/work[?dets=1&depth=1&ns=1]

The path portion following 'xdir' is taken as path; other parameters can
be send in query.

=head2 DTD

Resulting XML documents can be of three types. The type of document is specified in the constructor or using the C<set_details> method.

Level of details: 1 (brief)

 <!ELEMENT dirtree (directory)>
 <!ELEMENT directory (directory, file)>
 <!ATTLIST directory
           name CDATA #REQUIRED>
 <!ELEMENT file EMPTY>
 <!ATTLIST file
           name CDATA #REQUIRED>

Level of details: 2 (normal)

 <!ELEMENT dirtree (head, directory)>
 <!ELEMENT head (path, details, depth)>
 <!ATTLIST head
           version CDATA #REQUIRED>
 <!ELEMENT path (#PCDATA)>
 <!ELEMENT details (#PCDATA)>
 <!ELEMENT depth (#PCDATA)>
 <!ELEMENT directory (directory, file, path, modify-time)>
 <!ATTLIST directory
           name CDATA #REQUIRED>
 <!ELEMENT file (mode, size, modify-time)>
 <!ATTLIST file
           name CDATA #REQUIRED>
 <!ELEMENT modify-time (#PCDATA)>
 <!ATTLIST modify-time
           epoch NMTOKEN #REQUIRED>
 <!ELEMENT mode (#PCDATA)>
 <!ATTLIST mode
           code NMTOKEN #REQUIRED>
 <!ELEMENT size (#PCDATA)>
 <!ATTLIST size
           unit CDATA #FIXED "bytes">

Level of details: 3 (verbose)

 <!ELEMENT dirtree (head, directory)>
 <!ELEMENT head (path, details, depth)>
 <!ATTLIST head
           version CDATA #REQUIRED>
 <!ELEMENT path (#PCDATA)>
 <!ELEMENT details (#PCDATA)>
 <!ELEMENT depth (#PCDATA)>
 <!ELEMENT directory (directory, file, path, modify-time, access-time)>
 <!ATTLIST directory
           name CDATA #REQUIRED
           depth NMTOKEN #REQUIRED
           uid NMTOKEN #REQUIRED
           gid NMTOKEN #REQUIRED>
 <!ELEMENT file (mode, size, modify-time, access-time)>
 <!ATTLIST file
           name CDATA #REQUIRED
           uid NMTOKEN #REQUIRED
           gid NMTOKEN #REQUIRED>
 <!ELEMENT modify-time (#PCDATA)>
 <!ATTLIST modify-time
           epoch NMTOKEN #REQUIRED>
 <!ELEMENT access-time (#PCDATA)>
 <!ATTLIST access-time
           epoch NMTOKEN #REQUIRED>
 <!ELEMENT mode (#PCDATA)>
 <!ATTLIST mode
           code NMTOKEN #REQUIRED>
 <!ELEMENT size (#PCDATA)>
 <!ATTLIST size
           unit CDATA #FIXED "bytes">

There is also an modular DTD available, see the C<dtd> directory. 
You can take a look at an HTML documentation of this DTD by DTDParse
utility:

=over

=item *

=for html <a href="dirtree/level1/index.html">dirtree, level1</a>

=item *

=for html <a href="dirtree/level2/index.html">dirtree, level2</a>

=item *

=for html <a href="dirtree/level3/index.html">dirtree, level3</a>

=back

This DTD allows you to extend the list of allowable elements using parameter 
entities, so that extended XML files can be still validated.

An extended vocabulary can be either because of RDF/N3 metadata 
(see C<enable_rdf>), or, for instance, a directory of .dbk files, might be 
munged for <articleinfo> data which would be included in the output. The 
output could then be cached and munged again later using another SAX filter 
or XSLT.

This is how to extend the DTD:

 <?xml version = "1.0" ?>
 <!DOCTYPE dirtree SYSTEM [
   <!ENTITY % file "(mode,size,modify-time,foo)">
   <!ELEMENT foo (#PCDATA)>
 ]>...

=head1 VERSION

Current version is 0.99.

=head1 LICENSING

Copyright (c) 2001-2002 Ginger Alliance. All rights reserved. This program 
is free software; you can redistribute it and/or modify it under the same 
terms as Perl itself. 

=head1 AUTHOR

Petr Cimprich, petr@gingerall.cz

=head1 CONTRIBUTORS

Duncan Cameron, dcameron@bcs.org.uk

Chris Snyder, csnyder@longitude.com

Aaron Straup Cope, asc@vineyard.net

Gerhard Wannemacher, g.wannemacher@eurodata.de

=head1 SEE ALSO

perl(1), XML::SAX, RDF::Notation3.

=cut
