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=pod |
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=head1 NAME |
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Data::Storage - Interface for accessing various Storage implementations for Perl in an independent way |
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=head1 ABSTRACT ;-) |
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Data Storage |
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"Where is the wisdom? Lost in the knowledge. |
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Where is the knowledge? Lost in the information." |
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- T.S. Eliot |
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|
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"Where is the information? Lost in the data. |
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Where is the data? Lost in the #@$%?!& database." |
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- Joe Celko |
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|
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|
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from: MacPerl: Power and Ease - Chapter 15 |
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url: http://www.macperl.com/ptf_book/r/MP/330.Data_Storage.html |
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=head1 INTENTIONS |
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|
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- should encapsulate Tangram, DBI, DBD::CSV and LWP:: to access them in an unordinary (more convenient) way ;) |
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- introduce a generic layered structure, refactor *SUBLAYER*-stuff, make (e.g.) this possible: |
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Perl Data::Storage[DBD::CSV] -> Perl LWP:: -> Internet HTTP/FTP/* -> Host Daemon -> csv-file |
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- provide generic synchronization mechanisms across arbitrary/multiple storages based on ident/checksum |
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maybe it's possible to have schema-, structural- and semantical modifications synchronized??? |
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- might be similar to http://sourceforge.net/projects/perl-repository |
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|
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=head1 SYNOPSIS |
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|
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=head2 ACCESS |
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# connect to LDAP |
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my $ldapLocator = Data::Storage::Locator->new( |
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ldap => { |
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type => "NetLDAP", |
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dsn => "ldap:host=192.168.10.150;binddn='cn=root, o=netfrag.org, c=de';pass=secret", |
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basedn => "o=netfrag.org, c=de", |
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want_transactions => 0, |
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syncable => 1, |
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}, |
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); |
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my $ldapStorage = Data::Storage->new($ldapLocator); |
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$ldapStorage->connect(); |
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|
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# connect to MAPI |
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my $mapiLocator = Data::Storage::Locator->new( |
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outlook => { |
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type => "MAPI", |
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showProfileChooser => $self->{config}->get("mapi_showProfileChooser"), |
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ProfileName => $self->{config}->get("mapi_ProfileName"), |
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ProfilePass => $self->{config}->get("mapi_ProfilePass"), |
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syncable => 1, |
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}, |
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); |
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my $mapiStorage = Data::Storage->new($mapiLocator); |
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$mapiStorage->connect(); |
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|
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|
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=head2 SYNCHRONIZATION |
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This functionality is (in the meanwhile) provided by the Data::Transfer::Sync module. |
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=head3 proposal V1 |
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|
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my $nodemapping = { |
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'LangText' => 'langtexts.csv', |
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'Currency' => 'currencies.csv', |
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'Country' => 'countries.csv', |
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}; |
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|
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my $propmapping = { |
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'LangText' => [ |
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[ 'source:lcountrykey' => 'target:country' ], |
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[ 'source:lkey' => 'target:key' ], |
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[ 'source:lvalue' => 'target:text' ], |
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], |
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'Currency' => [ |
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[ 'source:ckey' => 'target:key' ], |
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[ 'source:cname' => 'target:text' ], |
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], |
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'Country' => [ |
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[ 'source:ckey' => 'target:key' ], |
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[ 'source:cname' => 'target:text' ], |
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], |
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}; |
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|
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s ub syncResource { |
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|
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my $self = shift; |
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my $node_source = shift; |
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my $mode = shift; |
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my $opts = shift; |
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|
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$mode ||= ''; |
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$opts->{erase} ||= 0; |
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$logger->info( __PACKAGE__ . "->syncResource( node_source $node_source mode $mode erase $opts->{erase} )"); |
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# resolve metadata for syncing requested resource |
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my $node_target = $nodemapping->{$node_source}; |
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my $mapping = $propmapping->{$node_source}; |
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|
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if (!$node_target || !$mapping) { |
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# loggger.... "no target, sorry!" |
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print "error while resolving resource metadata", "\n"; |
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return; |
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} |
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|
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if ($opts->{erase}) { |
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$self->_erase_all($node_source); |
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} |
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# create new sync object |
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my $sync = Data::Transfer::Sync->new( |
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storages => { |
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L => $self->{storage}->{backend}, |
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R => $self->{storage}->{resources}, |
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}, |
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id_authorities => [qw( L ) ], |
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checksum_authorities => [qw( L ) ], |
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write_protected => [qw( R ) ], |
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verbose => 1, |
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); |
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|
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# sync |
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# todo: filter!? |
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$sync->syncNodes( { |
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direction => $mode, # | +PUSH | +PULL | -FULL | +IMPORT | -EXPORT |
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method => 'checksum', # | -timestamp | -manual |
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source => "L:$node_source", |
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source_ident => 'storage_method:id', |
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source_exclude => [qw( id cs )], |
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target => "R:$node_target", |
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target_ident => 'property:oid', |
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mapping => $mapping, |
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} ); |
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|
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} |
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=head3 proposal V2 |
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# create a new synchronization object |
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my $sync = Data::Transfer::Sync->new( 'sync_version' => $sync_version, __parent => $self ); |
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# configure the synchronization-object |
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$sync->configure( |
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source => { |
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storage => { |
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handle => $mapiStorage, |
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#isIdentAuthority => 1, |
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#isChecksumAuthority => 1, |
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#writeProtected => 1, |
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}, |
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}, |
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target => { |
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storage => { |
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handle => $ldapStorage, |
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#idAuthority => 1, |
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#isChecksumAuthority => 1, |
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#isWriteProtected => 0, |
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}, |
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}, |
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verbose => 1, |
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); |
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=head2 NOTE |
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This module heavily relies on DBI and Tangram, but adds a lot of additional bugs and quirks. |
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Please look at their documentation and/or this code for additional information. |
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=head1 REQUIREMENTS |
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For full functionality: |
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DBI from CPAN |
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DBD::mysql from CPAN |
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Tangram 2.04 from CPAN (hmmm, 2.04 won't do in some cases) |
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Tangram 2.05 from http://... (2.05 seems okay but there are also additional patches from our side) |
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Class::Tangram from CPAN |
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DBD::CSV from CPAN |
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MySQL::Diff from http://adamspiers.org/computing/mysqldiff/ |
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... and all their dependencies |
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=head1 DESCRIPTION |
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|
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=head2 Data::Storage |
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Data::Storage is a module for accessing various "data structures / kinds of structured data" stored inside |
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various "data containers". |
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We tried to use the AdapterPattern to implement a wrapper-layer around known CPAN modules. |
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(e.g. DBI, Tangram, XML::Simple) |
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References: |
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- http://c2.com/cgi/wiki?AdapterPattern |
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- http://home.earthlink.net/~huston2/dp/adapter.html |
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=head2 Why? |
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You will get a better code-structure (not bad for later maintenance) in growing Perl code projects, |
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especially when using multiple database connections at the same time. |
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You will be able to switch between different _kinds_ of implementations used for storing data. |
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Your code will use the very same API to access these storage layers. |
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... implementation has to be changed for now |
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Maybe you will be able to switch "on-the-fly" without changing any bits in code in the future.... |
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... but that's not the focus |
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=head2 What else? |
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Having this, we were able to do implement a generic data synchronization module more easy, |
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please look at Data::Transfer. |
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=head1 AUTHORS / COPYRIGHT |
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The Data::Storage module is Copyright (c) 2002 Andreas Motl. |
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All rights reserved. |
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You may distribute it under the terms of either the GNU General Public |
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License or the Artistic License, as specified in the Perl README file. |
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=head1 ACKNOWLEDGEMENTS |
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|
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Larry Wall for Perl, Tim Bunce for DBI, Jean-Louis Leroy for Tangram and Set::Object, |
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Sam Vilain for Class::Tangram, Jochen Wiedmann and Jeff Zucker for DBD::CSV & Co., |
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Adam Spiers for MySQL::Diff and all contributors. |
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=head1 SUPPORT / WARRANTY |
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Data::Storage is free software. IT COMES WITHOUT WARRANTY OF ANY KIND. |
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=head1 TODO |
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o interface with Jeff Zucker's AnyData:: modules, e.g. AnyData::Storage::RAM |
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o what about DBD::RAM? (DBD::RAM - a DBI driver for files and data structures) |
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o use DBD::Proxy! |
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o what about DBIx::AnyDBD? |
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o enhance schema information: |
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- DBIx::SystemCatalog |
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- DBIx::SystemCatalog::MSSQL? |
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- Data::Reporter |
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|
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=head2 BUGS |
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"DBI-Error [Tangram]: DBD::mysql::st execute failed: Unknown column 't1.requestdump' in 'field list'" |
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... occours when operating on object-attributes not introduced yet: |
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this should be detected and appended/replaced through: |
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"Schema-Error detected, maybe (just) an inconsistency. |
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Please check if your declaration in schema-module "a" matches structure in database "b" or try to run" |
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db_setup.pl --dbkey=import --action=deploy |
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Compare schema (structure diff) with database ... |
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... when issuing "db_setup.pl --dbkey=import --action=deploy" |
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on a database with an already deployed schema, use an additional "--update" then |
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to lift the schema inside the database to the current declared schema. |
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You will have to approve removals and changes on field-level while |
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new objects and new fields are introduced silently without any interaction needed. |
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In future versions there may be additional options to control silent processing of |
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removals and changes. |
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See this CRUD-table applying to the actions occouring on Classes and Class variables when deploying schemas, |
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don't mix this up with CRUD-actions on Objects, these are already handled by (e.g.) Tangram itself. |
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Classes: |
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C create -> yes, handled automatically |
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R retrieve -> no, not subject of this aspect since it is about deployment only |
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U update -> yes, automatically for Class meta-attributes, yes/no for Class variables (look at the rules down here) |
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D delete -> yes, just by user-interaction |
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Class variables: |
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C create -> yes, handled automatically |
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R retrieve -> no, not subject of this aspect since it is about deployment only |
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U update -> yes, just by user-interaction; maybe automatically if it can be determined that data wouldn't be lost |
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D delete -> yes, just by user-interaction |
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|
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It's all about not to be able to loose data simply while this is in pre-alpha stage. |
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And loosing data by being able to modify and redeploy schemas easily is definitely quite easy. |
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As we can see, creations of Classes and new Class variables is handled |
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automatically and this is believed to be the most common case under normal circumstances. |
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|
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=head2 FEATURES |
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|
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- Get this stuff together with UML (Unified Modeling Language) and/or standards from ODMG. |
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- Make it possible to load/save schemas in XMI (XML Metadata Interchange), |
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which seems to be most commonly used today, perhaps handle objects with OIFML. |
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Integrate/bundle this with a web-/html-based UML modeling tool or |
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some other interesting stuff like the "Co-operative UML Editor" from Uni Darmstadt. (web-/java-based) |
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- Enable Round Trip Engineering. Keep code and diagrams in sync. Don't annoy/bother the programmers. |
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- Add support for some more handlers/locators to be able to |
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access the following standards/protocols/interfaces/programs/apis transparently: |
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+ DBD::CSV (via Data::Storage::Handler::DBI) |
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(-) Text::CSV, XML::CSV, XML::Excel |
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- MAPI |
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- LDAP |
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- DAV (look at PerlDAV: http://www.webdav.org/perldav/) |
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- Mbox (use formail for seperating/splitting entries/nodes) |
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- Cyrus (cyrdeliver - what about cyrretrieve (export)???) |
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- use File::DiffTree, use File::Compare |
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- Hibernate |
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- "Win32::UserAccountDb" |
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- "*nix::UserAccountDb" |
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- .wab - files (Windows Address Book) |
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- .pst - files (Outlook Post Storage?) |
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- XML (e.g. via XML::Simple?) |
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- Move to t3, look at InCASE |
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- some kind of security layer for methods/objects |
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- acls (stored via tangram/ldap?) for functions, methods and objects (entity- & data!?) |
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- where are the hooks needed then? |
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- is Data::Storage & Co. okay, or do we have to touch the innards of DBI and/or Tangram? |
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- an attempt to start could be: |
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- 'sub getACLByObjectId($id, $context)' |
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- 'sub getACLByMethodname($id, $context)' |
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- 'sub getACLByName($id, $context)' |
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( would require a kinda registry to look up these very names pointing to arbitrary locations (code, data, ...) ) |
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- add more hooks and various levels |
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- better integrate introduced 'getObjectByGuid'-mechanism from Data::Storage::Handler::Tangram |
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=head3 LINKS / REFERENCES |
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|
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Specs: |
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UML 1.3 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-06-08.pdf |
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XMI 1.1 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-10-02.pdf |
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XMI 2.0 Spec: http://cgi.omg.org/docs/ad/01-06-12.pdf |
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ODMG: http://odmg.org/ |
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OIFML: http://odmg.org/library/readingroom/oifml.pdf |
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|
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CASE Tools: |
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Rational Rose (commercial): http://www.rational.com/products/rose/ |
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Together (commercial): http://www.oi.com/products/controlcenter/index.jsp |
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InCASE - Tangram-based Universal Object Editor |
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Sybase PowerDesigner: http://www.sybase.com/powerdesigner |
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|
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UML Editors: |
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Fujaba (free, university): http://www.fujaba.de/ |
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ArgoUML (free): http://argouml.tigris.org/ |
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Poseidon (commercial): http://www.gentleware.com/products/poseidonDE.php3 |
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Co-operative UML Editor (research): http://www.darmstadt.gmd.de/concert/activities/internal/umledit.html |
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Metamill (commercial): http://www.metamill.com/ |
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Violet (university, research, education): http://www.horstmann.com/violet/ |
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PyUt (free): http://pyut.sourceforge.net/ |
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(Dia (free): http://www.lysator.liu.se/~alla/dia/) |
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UMLet (free, university): http://www.swt.tuwien.ac.at/umlet/index.html |
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Voodoo (free): http://voodoo.sourceforge.net/ |
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Umbrello UML Modeller: http://uml.sourceforge.net/ |
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|
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UML Tools: |
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http://www.objectsbydesign.com/tools/umltools_byPrice.html |
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|
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Further readings: |
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http://www.google.com/search?q=web+based+uml+editor&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=10&sa=N |
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http://www.fernuni-hagen.de/DVT/Aktuelles/01FHHeidelberg.pdf |
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http://www.enhyper.com/src/documentation/ |
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http://cis.cs.tu-berlin.de/Dokumente/Diplomarbeiten/2001/skinner.pdf |
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http://citeseer.nj.nec.com/vilain00diagrammatic.html |
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http://archive.devx.com/uml/articles/Smith01/Smith01-3.asp |
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|
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|
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=cut |
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