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package WebPAC::DB; |
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|
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use warnings; |
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use strict; |
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|
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use base 'WebPAC::Common'; |
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use Storable; |
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|
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=head1 NAME |
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|
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WebPAC::DB - Store normalized data on disk |
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|
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=head1 VERSION |
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|
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Version 0.01 |
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|
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=cut |
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|
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our $VERSION = '0.01'; |
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|
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=head1 SYNOPSIS |
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|
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This module provides disk storage for normalised data. |
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|
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It is newest component of WebPAC, so it will change quite often or be in |
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flux. However, I will try to keep backward compatiblity by providing |
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multiple back-ends. |
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|
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This has additional advantage. I can create single place to plugin other |
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file formats which provide better performance for particular type of data. |
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|
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For now, this is a prototype version. |
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|
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use WebPAC::DB; |
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|
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my $foo = WebPAC::DB->new(); |
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... |
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|
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=head1 FUNCTIONS |
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|
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=head2 new |
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|
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Create new normalised database object |
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my $db = new WebPAC::DB( |
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path => '/path/to/cache/ds/', |
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read_only => 1, |
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); |
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|
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Optional parameter C<path> defines path to directory |
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in which cache file for C<data_structure> call will be created. |
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|
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If called with C<read_only> it will not disable caching if |
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called without write permission (but will die on C<save_ds>). |
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|
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=cut |
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|
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sub new { |
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my $class = shift; |
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my $self = {@_}; |
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bless($self, $class); |
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|
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$self->path( $self->{'path'} ); |
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|
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$self ? return $self : return undef; |
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} |
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|
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=head2 path |
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|
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Check if specified cache directory exist, and if not, disable caching. |
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|
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$db->path('./cache/ds/'); |
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|
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If you pass false or zero value to this function, it will disable |
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cacheing. |
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|
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=cut |
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|
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sub path { |
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my $self = shift; |
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|
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my $dir = shift; |
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|
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my $log = $self->_get_logger(); |
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|
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if ($dir) { |
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my $msg; |
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if (! -e $dir) { |
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$msg = "doesn't exist"; |
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} elsif (! -d $dir) { |
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$msg = "is not directory"; |
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} elsif (! -w $dir) { |
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$msg = "not writable" unless ($self->{'read_only'}); |
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} |
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|
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if ($msg) { |
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$log->warn("cache path $dir $msg, disabling..."); |
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undef $self->{'path'}; |
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} else { |
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$log->debug("using cache dir $dir"); |
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$self->{'path'} = $dir; |
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} |
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} else { |
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$log->debug("disabling cache"); |
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undef $self->{'path'}; |
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} |
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} |
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|
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=head2 load_ds |
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|
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Retrive from disk one data_structure records using field 000 as key |
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|
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my @ds = $db->load_ds($rec); |
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|
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This function will also perform basic sanity checking on returned |
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data and disable caching if data is corrupted (or changed since last |
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update). |
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|
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Returns array or undef if cacheing is disabled or unavailable. |
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|
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=cut |
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|
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sub load_ds { |
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my $self = shift; |
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return unless $self->{'path'}; |
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|
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my $rec = shift || return; |
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|
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my $log = $self->_get_logger; |
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|
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my $cache_path = $self->{'path'}; |
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|
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my $id = $rec; |
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$id = $rec->{'000'} if (ref($id) eq 'HASH'); |
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$id = $rec->{'000'}->[0] if (ref($id) eq 'ARRAY'); |
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|
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unless (defined($id)) { |
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$log->warn("Can't use cacheing on records without unique identifier in field 000"); |
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undef $self->{'path'}; |
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} else { |
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my $cache_file = "$cache_path/$id"; |
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$self->{'cache_file'} = $cache_file; |
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if (-r $cache_file) { |
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my $ds_ref = retrieve($cache_file); |
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if ($ds_ref) { |
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$log->debug("cache hit: $cache_file"); |
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my $ok = 1; |
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foreach my $f (qw(current_filename headline)) { |
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if ($ds_ref->{$f}) { |
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$self->{$f} = $ds_ref->{$f}; |
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} else { |
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$ok = 0; |
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} |
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}; |
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if ($ok && $ds_ref->{'ds'}) { |
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return @{ $ds_ref->{'ds'} }; |
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} else { |
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$log->warn("cache entry $cache_path corrupt. Use rm $cache_path/* to re-create it on next run!"); |
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undef $self->{'path'}; |
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} |
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} |
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} |
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} |
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|
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return undef; |
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} |
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|
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=head2 save_ds |
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|
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Store data_structure on disk. |
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|
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$db->save_ds( |
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ds => \@ds, |
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current_filename => $self->{'current_filename'}, |
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headline => $self->{'headline'}, |
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); |
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|
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B<Totally broken, but fast.> |
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|
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Depends on filename generated by C<load_ds>. |
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|
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=cut |
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|
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sub save_ds { |
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my $self = shift; |
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die "can't write to database in read_only mode!" if ($self->{'read_only'}); |
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|
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return unless($self->{'path'}); |
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return unless (@_); |
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|
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my $arg = {@_}; |
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|
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my $log = $self->_get_logger; |
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|
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$log->logdie("save_ds without cache_file -- did you called gs_get before?") unless ($self->{'cache_file'}); |
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foreach my $e (qw/ds current_filename headline/) { |
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$log->logconfess("missing $e") unless $arg->{$e}; |
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} |
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$log->debug("creating storable cache file ",$self->{'cache_file'}); |
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|
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store { |
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ds => $arg->{'ds'}, |
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current_filename => $arg->{'current_filename'}, |
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headline => $arg->{'headline'}, |
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}, $self->{'cache_file'}; |
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|
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} |
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|
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=head1 AUTHOR |
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|
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Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >> |
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=head1 COPYRIGHT & LICENSE |
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Copyright 2005 Dobrica Pavlinusic, All Rights Reserved. |
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This program is free software; you can redistribute it and/or modify it |
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under the same terms as Perl itself. |
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|
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=cut |
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|
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1; # End of WebPAC::DB |
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