libs/Data/Storage.README.text

NAME
      Data::Storage - Interface for accessing various Storage implementations for Perl in an independent way

AIMS
      - should encapsulate Tangram, DBI, DBD::CSV and LWP:: to access them in an unordinary (more convenient) way ;)
      - introduce a generic layered structure, refactor *SUBLAYER*-stuff, make (e.g.) this possible:
        Perl Data::Storage[DBD::CSV]  ->  Perl LWP::  ->  Internet HTTP/FTP/*  ->  Host Daemon  ->  csv-file
      - provide generic synchronization mechanisms across arbitrary/multiple storages based on ident/checksum
        maybe it's possible to have schema-, structural- and semantical modifications synchronized???

SYNOPSIS
  BASIC ACCESS

  ADVANCED ACCESS

      ... via inheritance:
  
        use Data::Storage;
        my $proxyObj = new HttpProxy;
        $proxyObj->{url} = $url;
        $proxyObj->{payload} = $content;
        $self->{storage}->insert($proxyObj);
    
        use Data::Storage;
        my $proxyObj = HttpProxy->new(
          url => $url,
          payload => $content,
        );
        $self->{storage}->insert($proxyObj);

  SYNCHRONIZATION

      my $nodemapping = {
        'LangText' => 'langtexts.csv',
        'Currency' => 'currencies.csv',
        'Country'  => 'countries.csv',
      };

      my $propmapping = {
        'LangText' => [
          [ 'source:lcountrykey'  =>  'target:country' ],
          [ 'source:lkey'         =>  'target:key' ],
          [ 'source:lvalue'       =>  'target:text' ],
        ],
        'Currency' => [
          [ 'source:ckey'         =>  'target:key' ],
          [ 'source:cname'        =>  'target:text' ],
        ],
        'Country' => [
          [ 'source:ckey'         =>  'target:key' ],
          [ 'source:cname'        =>  'target:text' ],
        ],
      };

      s ub syncResource {

        my $self = shift;
        my $node_source = shift;
        my $mode = shift;
        my $opts = shift;
    
        $mode ||= '';
        $opts->{erase} ||= 0;
    
        $logger->info( __PACKAGE__ . "->syncResource( node_source $node_source mode $mode erase $opts->{erase} )");
  
        # resolve metadata for syncing requested resource
        my $node_target = $nodemapping->{$node_source};
        my $mapping = $propmapping->{$node_source};
    
        if (!$node_target || !$mapping) {
          # loggger.... "no target, sorry!"
          print "error while resolving resource metadata", "\n";
          return;
        }
    
        if ($opts->{erase}) {
          $self->_erase_all($node_source);
        }
  
        # create new sync object
        my $sync = Data::Transfer::Sync->new( 
          storages => {
            L => $self->{bizWorks}->{backend},
            R => $self->{bizWorks}->{resources},
          },
          id_authorities        =>  [qw( L ) ],
          checksum_authorities  =>  [qw( L ) ],
          write_protected       =>  [qw( R ) ],
          verbose               =>  1,
        );
    
        # sync
        # todo: filter!?
        $sync->syncNodes( {
          direction       =>  $mode,                 # | +PUSH | +PULL | -FULL | +IMPORT | -EXPORT
          method          =>  'checksum',            # | -timestamp | -manual
          source          =>  "L:$node_source",
          source_ident    =>  'storage_method:id',
          source_exclude  =>  [qw( id cs )],
          target          =>  "R:$node_target",
          target_ident    =>  'property:oid',
          mapping         =>  $mapping,
        } );

      }

  NOTE

      This module heavily relies on DBI and Tangram, but adds a lot of additional bugs and quirks. 
      Please look at their documentation and/or this code for additional information.

REQUIREMENTS
      For full functionality:
        DBI              from CPAN
        DBD::mysql       from CPAN
        Tangram 2.04     from CPAN         (hmmm, 2.04 won't do in some cases)
        Tangram 2.05     from http://...   (2.05 seems okay but there are also additional patches from our side)
        Class::Tangram   from CPAN
        DBD::CSV         from CPAN
        MySQL::Diff      from http://adamspiers.org/computing/mysqldiff/
        ... and all their dependencies

DESCRIPTION
  Data::Storage

      Data::Storage is a module for accessing various "data structures / kinds of structured data" stored inside
      various "data containers".
      We tried to use the AdapterPattern to implement a wrapper-layer around known CPAN modules.
      (e.g. DBI, Tangram, XML::Simple)
      References:
      - http://c2.com/cgi/wiki?AdapterPattern
      - http://home.earthlink.net/~huston2/dp/adapter.html

  Why?

      You will get a better code-structure (not bad for later maintenance) in growing Perl code projects,
      especially when using multiple database connections at the same time.
      You will be able to switch between different _kinds_ of implementations used for storing data.
      Your code will use the very same API to access these storage layers.
          ... implementation has to be changed for now
      Maybe you will be able to switch "on-the-fly" without changing any bits in code in the future.... 
          ... but that's not the focus

  What else?

      Having this, we were able to do implement a generic data synchronization module more easy,
      please look at Data::Transfer.

AUTHORS / COPYRIGHT
      The Data::Storage module is Copyright (c) 2002 Andreas Motl.
      All rights reserved.
      You may distribute it under the terms of either the GNU General Public
      License or the Artistic License, as specified in the Perl README file.

ACKNOWLEDGEMENTS
      Larry Wall for Perl, Tim Bunce for DBI, Jean-Louis Leroy for Tangram and Set::Object, 
      Sam Vilain for Class::Tangram, Jochen Wiedmann and Jeff Zucker for DBD::CSV & Co.,
      Adam Spiers for MySQL::Diff and all contributors.

SUPPORT / WARRANTY
      Data::Storage is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.

TODO
  BUGS

    "DBI-Error [Tangram]: DBD::mysql::st execute failed: Unknown column
    't1.requestdump' in 'field list'"

      ... occours when operating on object-attributes not introduced yet:
      this should be detected and appended/replaced through:
      "Schema-Error detected, maybe (just) an inconsistency. 
      Please check if your declaration in schema-module "a" matches structure in database "b" or try to run"
      db_setup.pl --dbkey=import --action=deploy

    Compare schema (structure diff) with database ...

      ... when issuing "db_setup.pl --dbkey=import --action=deploy"
      on a database with an already deployed schema, use an additional "--update" then
      to lift the schema inside the database to the current declared schema.
      You will have to approve removals and changes on field-level while
      new objects and new fields are introduced silently without any interaction needed.
      In future versions there may be additional options to control silent processing of
      removals and changes.
      See this CRUD-table applying to the actions occouring on Classes and Class variables when deploying schemas,
      don't mix this up with CRUD-actions on Objects, these are already handled by (e.g.) Tangram itself.
      Classes:
        C create    ->  yes, handled automatically
        R retrieve  ->  no, not subject of this aspect since it is about deployment only
        U update    ->  yes, automatically for Class meta-attributes, yes/no for Class variables (look at the rules down here)
        D delete    ->  yes, just by user-interaction
      Class variables:
        C create    ->  yes, handled automatically
        R retrieve  ->  no, not subject of this aspect since it is about deployment only
        U update    ->  yes, just by user-interaction; maybe automatically if it can be determined that data wouldn't be lost
        D delete    ->  yes, just by user-interaction
  
      It's all about not to be able to loose data simply while this is in pre-alpha stage.
      And loosing data by being able to modify and redeploy schemas easily is definitely quite easy.
  
      As we can see, creations of Classes and new Class variables is handled 
      automatically and this is believed to be the most common case under normal circumstances.

  FEATURES

      - Get this stuff together with UML (Unified Modeling Language) and/or standards from ODMG.
      - Make it possible to load/save schemas in XMI (XML Metadata Interchange), 
        which seems to be most commonly used today, perhaps handle objects with OIFML.
        Integrate/bundle this with a web-/html-based UML modeling tool or 
        some other interesting stuff like the "Co-operative UML Editor" from Uni Darmstadt. (web-/java-based)
      - Enable Round Trip Engineering. Keep code and diagrams in sync. Don't annoy/bother the programmers.
      - Add support for some more handlers/locators to be able to 
         access the following standards/protocols/interfaces/programs/apis transparently:
        +  DBD::CSV (via Data::Storage::Handler::DBI)
       (-) Text::CSV, XML::CSV, XML::Excel
        -  MAPI
        -  LDAP
        -  DAV (look at PerlDAV: http://www.webdav.org/perldav/)
        -  Mbox (use formail for seperating/splitting entries/nodes)
        -  Cyrus (cyrdeliver - what about cyrretrieve (export)???)
        -  use File::DiffTree, use File::Compare
        -  Hibernate
        -  "Win32::UserAccountDb"
        -  "*nix::UserAccountDb"
        -  .wab - files (Windows Address Book)
        -  .pst - files (Outlook Post Storage?)
        -  XML (e.g. via XML::Simple?)
      - Move to t3, look at InCASE
      - some kind of security layer for methods/objects
        - acls (stored via tangram/ldap?) for functions, methods and objects (entity- & data!?)
        - where are the hooks needed then?
          - is Data::Storage & Co. okay, or do we have to touch the innards of DBI and/or Tangram?
          - an attempt to start could be: 
             - 'sub getACLByObjectId($id, $context)'
             - 'sub getACLByMethodname($id, $context)'
             - 'sub getACLByName($id, $context)'
                ( would require a kinda registry to look up these very names pointing to arbitrary locations (code, data, ...) )
      - add more hooks and various levels
      - better integrate introduced 'getObjectByGuid'-mechanism from Data::Storage::Handler::Tangram

   LINKS / REFERENCES

      Specs:
        UML 1.3 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-06-08.pdf
        XMI 1.1 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-10-02.pdf
        XMI 2.0 Spec: http://cgi.omg.org/docs/ad/01-06-12.pdf
        ODMG: http://odmg.org/
        OIFML: http://odmg.org/library/readingroom/oifml.pdf

      CASE Tools:
        Rational Rose (commercial): http://www.rational.com/products/rose/
        Together (commercial): http://www.oi.com/products/controlcenter/index.jsp
        InCASE - Tangram-based Universal Object Editor 
        Sybase PowerDesigner: http://www.sybase.com/powerdesigner
  
      UML Editors:
        Fujaba (free, university): http://www.fujaba.de/
        ArgoUML (free): http://argouml.tigris.org/
        Poseidon (commercial): http://www.gentleware.com/products/poseidonDE.php3
        Co-operative UML Editor (research): http://www.darmstadt.gmd.de/concert/activities/internal/umledit.html
        Metamill (commercial): http://www.metamill.com/
        Violet (university, research, education): http://www.horstmann.com/violet/
        PyUt (free): http://pyut.sourceforge.net/
        (Dia (free): http://www.lysator.liu.se/~alla/dia/)
        UMLet (free, university): http://www.swt.tuwien.ac.at/umlet/index.html
        Voodoo (free): http://voodoo.sourceforge.net/
        Umbrello UML Modeller: http://uml.sourceforge.net/

      UML Tools:
        http://www.objectsbydesign.com/tools/umltools_byPrice.html

      Further readings:
        http://www.google.com/search?q=web+based+uml+editor&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=10&sa=N
        http://www.fernuni-hagen.de/DVT/Aktuelles/01FHHeidelberg.pdf
        http://www.enhyper.com/src/documentation/
        http://cis.cs.tu-berlin.de/Dokumente/Diplomarbeiten/2001/skinner.pdf
        http://citeseer.nj.nec.com/vilain00diagrammatic.html
        http://archive.devx.com/uml/articles/Smith01/Smith01-3.asp

1	joko	1.1	NAME
2			Data::Storage - Interface for accessing various Storage implementations for Perl in an independent way
3
4			AIMS
5			- should encapsulate Tangram, DBI, DBD::CSV and LWP:: to access them in an unordinary (more convenient) way ;)
6			- introduce a generic layered structure, refactor SUBLAYER-stuff, make (e.g.) this possible:
7			Perl Data::Storage[DBD::CSV] -> Perl LWP:: -> Internet HTTP/FTP/* -> Host Daemon -> csv-file
8			- provide generic synchronization mechanisms across arbitrary/multiple storages based on ident/checksum
9			maybe it's possible to have schema-, structural- and semantical modifications synchronized???
10
11			SYNOPSIS
12			BASIC ACCESS
13
14			ADVANCED ACCESS
15
16			... via inheritance:
17
18			use Data::Storage;
19			my $proxyObj = new HttpProxy;
20			$proxyObj->{url} = $url;
21			$proxyObj->{payload} = $content;
22			$self->{storage}->insert($proxyObj);
23
24			use Data::Storage;
25			my $proxyObj = HttpProxy->new(
26			url => $url,
27			payload => $content,
28			);
29			$self->{storage}->insert($proxyObj);
30
31			SYNCHRONIZATION
32
33			my $nodemapping = {
34			'LangText' => 'langtexts.csv',
35			'Currency' => 'currencies.csv',
36			'Country' => 'countries.csv',
37			};
38
39			my $propmapping = {
40			'LangText' => [
41			[ 'source:lcountrykey' => 'target:country' ],
42			[ 'source:lkey' => 'target:key' ],
43			[ 'source:lvalue' => 'target:text' ],
44			],
45			'Currency' => [
46			[ 'source:ckey' => 'target:key' ],
47			[ 'source:cname' => 'target:text' ],
48			],
49			'Country' => [
50			[ 'source:ckey' => 'target:key' ],
51			[ 'source:cname' => 'target:text' ],
52			],
53			};
54
55			s ub syncResource {
56
57			my $self = shift;
58			my $node_source = shift;
59			my $mode = shift;
60			my $opts = shift;
61
62			$mode \|\|= '';
63			$opts->{erase} \|\|= 0;
64
65			$logger->info( __PACKAGE__ . "->syncResource( node_source $node_source mode $mode erase $opts->{erase} )");
66
67			# resolve metadata for syncing requested resource
68			my $node_target = $nodemapping->{$node_source};
69			my $mapping = $propmapping->{$node_source};
70
71			if (!$node_target \|\| !$mapping) {
72			# loggger.... "no target, sorry!"
73			print "error while resolving resource metadata", "\n";
74			return;
75			}
76
77			if ($opts->{erase}) {
78			$self->_erase_all($node_source);
79			}
80
81			# create new sync object
82			my $sync = Data::Transfer::Sync->new(
83			storages => {
84			L => $self->{bizWorks}->{backend},
85			R => $self->{bizWorks}->{resources},
86			},
87			id_authorities => [qw( L ) ],
88			checksum_authorities => [qw( L ) ],
89			write_protected => [qw( R ) ],
90			verbose => 1,
91			);
92
93			# sync
94			# todo: filter!?
95			$sync->syncNodes( {
96			direction => $mode, # \| +PUSH \| +PULL \| -FULL \| +IMPORT \| -EXPORT
97			method => 'checksum', # \| -timestamp \| -manual
98			source => "L:$node_source",
99			source_ident => 'storage_method:id',
100			source_exclude => [qw( id cs )],
101			target => "R:$node_target",
102			target_ident => 'property:oid',
103			mapping => $mapping,
104			} );
105
106			}
107
108			NOTE
109
110			This module heavily relies on DBI and Tangram, but adds a lot of additional bugs and quirks.
111			Please look at their documentation and/or this code for additional information.
112
113			REQUIREMENTS
114			For full functionality:
115			DBI from CPAN
116			DBD::mysql from CPAN
117			Tangram 2.04 from CPAN (hmmm, 2.04 won't do in some cases)
118			Tangram 2.05 from http://... (2.05 seems okay but there are also additional patches from our side)
119			Class::Tangram from CPAN
120			DBD::CSV from CPAN
121			MySQL::Diff from http://adamspiers.org/computing/mysqldiff/
122			... and all their dependencies
123
124			DESCRIPTION
125			Data::Storage
126
127			Data::Storage is a module for accessing various "data structures / kinds of structured data" stored inside
128			various "data containers".
129			We tried to use the AdapterPattern to implement a wrapper-layer around known CPAN modules.
130			(e.g. DBI, Tangram, XML::Simple)
131			References:
132			- http://c2.com/cgi/wiki?AdapterPattern
133			- http://home.earthlink.net/~huston2/dp/adapter.html
134
135			Why?
136
137			You will get a better code-structure (not bad for later maintenance) in growing Perl code projects,
138			especially when using multiple database connections at the same time.
139			You will be able to switch between different _kinds_ of implementations used for storing data.
140			Your code will use the very same API to access these storage layers.
141			... implementation has to be changed for now
142			Maybe you will be able to switch "on-the-fly" without changing any bits in code in the future....
143			... but that's not the focus
144
145			What else?
146
147			Having this, we were able to do implement a generic data synchronization module more easy,
148			please look at Data::Transfer.
149
150			AUTHORS / COPYRIGHT
151			The Data::Storage module is Copyright (c) 2002 Andreas Motl.
152			All rights reserved.
153			You may distribute it under the terms of either the GNU General Public
154			License or the Artistic License, as specified in the Perl README file.
155
156			ACKNOWLEDGEMENTS
157			Larry Wall for Perl, Tim Bunce for DBI, Jean-Louis Leroy for Tangram and Set::Object,
158			Sam Vilain for Class::Tangram, Jochen Wiedmann and Jeff Zucker for DBD::CSV & Co.,
159			Adam Spiers for MySQL::Diff and all contributors.
160
161			SUPPORT / WARRANTY
162			Data::Storage is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.
163
164			TODO
165			BUGS
166
167			"DBI-Error [Tangram]: DBD::mysql::st execute failed: Unknown column
168			't1.requestdump' in 'field list'"
169
170			... occours when operating on object-attributes not introduced yet:
171			this should be detected and appended/replaced through:
172			"Schema-Error detected, maybe (just) an inconsistency.
173			Please check if your declaration in schema-module "a" matches structure in database "b" or try to run"
174			db_setup.pl --dbkey=import --action=deploy
175
176			Compare schema (structure diff) with database ...
177
178			... when issuing "db_setup.pl --dbkey=import --action=deploy"
179			on a database with an already deployed schema, use an additional "--update" then
180			to lift the schema inside the database to the current declared schema.
181			You will have to approve removals and changes on field-level while
182			new objects and new fields are introduced silently without any interaction needed.
183			In future versions there may be additional options to control silent processing of
184			removals and changes.
185			See this CRUD-table applying to the actions occouring on Classes and Class variables when deploying schemas,
186			don't mix this up with CRUD-actions on Objects, these are already handled by (e.g.) Tangram itself.
187			Classes:
188			C create -> yes, handled automatically
189			R retrieve -> no, not subject of this aspect since it is about deployment only
190			U update -> yes, automatically for Class meta-attributes, yes/no for Class variables (look at the rules down here)
191			D delete -> yes, just by user-interaction
192			Class variables:
193			C create -> yes, handled automatically
194			R retrieve -> no, not subject of this aspect since it is about deployment only
195			U update -> yes, just by user-interaction; maybe automatically if it can be determined that data wouldn't be lost
196			D delete -> yes, just by user-interaction
197
198			It's all about not to be able to loose data simply while this is in pre-alpha stage.
199			And loosing data by being able to modify and redeploy schemas easily is definitely quite easy.
200
201			As we can see, creations of Classes and new Class variables is handled
202			automatically and this is believed to be the most common case under normal circumstances.
203
204			FEATURES
205
206			- Get this stuff together with UML (Unified Modeling Language) and/or standards from ODMG.
207			- Make it possible to load/save schemas in XMI (XML Metadata Interchange),
208			which seems to be most commonly used today, perhaps handle objects with OIFML.
209			Integrate/bundle this with a web-/html-based UML modeling tool or
210			some other interesting stuff like the "Co-operative UML Editor" from Uni Darmstadt. (web-/java-based)
211			- Enable Round Trip Engineering. Keep code and diagrams in sync. Don't annoy/bother the programmers.
212			- Add support for some more handlers/locators to be able to
213			access the following standards/protocols/interfaces/programs/apis transparently:
214			+ DBD::CSV (via Data::Storage::Handler::DBI)
215			(-) Text::CSV, XML::CSV, XML::Excel
216			- MAPI
217			- LDAP
218			- DAV (look at PerlDAV: http://www.webdav.org/perldav/)
219			- Mbox (use formail for seperating/splitting entries/nodes)
220			- Cyrus (cyrdeliver - what about cyrretrieve (export)???)
221			- use File::DiffTree, use File::Compare
222			- Hibernate
223			- "Win32::UserAccountDb"
224			- "*nix::UserAccountDb"
225			- .wab - files (Windows Address Book)
226			- .pst - files (Outlook Post Storage?)
227			- XML (e.g. via XML::Simple?)
228			- Move to t3, look at InCASE
229			- some kind of security layer for methods/objects
230			- acls (stored via tangram/ldap?) for functions, methods and objects (entity- & data!?)
231			- where are the hooks needed then?
232			- is Data::Storage & Co. okay, or do we have to touch the innards of DBI and/or Tangram?
233			- an attempt to start could be:
234			- 'sub getACLByObjectId($id, $context)'
235			- 'sub getACLByMethodname($id, $context)'
236			- 'sub getACLByName($id, $context)'
237			( would require a kinda registry to look up these very names pointing to arbitrary locations (code, data, ...) )
238			- add more hooks and various levels
239			- better integrate introduced 'getObjectByGuid'-mechanism from Data::Storage::Handler::Tangram
240
241			LINKS / REFERENCES
242
243			Specs:
244			UML 1.3 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-06-08.pdf
245			XMI 1.1 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-10-02.pdf
246			XMI 2.0 Spec: http://cgi.omg.org/docs/ad/01-06-12.pdf
247			ODMG: http://odmg.org/
248			OIFML: http://odmg.org/library/readingroom/oifml.pdf
249
250			CASE Tools:
251			Rational Rose (commercial): http://www.rational.com/products/rose/
252			Together (commercial): http://www.oi.com/products/controlcenter/index.jsp
253			InCASE - Tangram-based Universal Object Editor
254			Sybase PowerDesigner: http://www.sybase.com/powerdesigner
255
256			UML Editors:
257			Fujaba (free, university): http://www.fujaba.de/
258			ArgoUML (free): http://argouml.tigris.org/
259			Poseidon (commercial): http://www.gentleware.com/products/poseidonDE.php3
260			Co-operative UML Editor (research): http://www.darmstadt.gmd.de/concert/activities/internal/umledit.html
261			Metamill (commercial): http://www.metamill.com/
262			Violet (university, research, education): http://www.horstmann.com/violet/
263			PyUt (free): http://pyut.sourceforge.net/
264			(Dia (free): http://www.lysator.liu.se/~alla/dia/)
265			UMLet (free, university): http://www.swt.tuwien.ac.at/umlet/index.html
266			Voodoo (free): http://voodoo.sourceforge.net/
267			Umbrello UML Modeller: http://uml.sourceforge.net/
268
269			UML Tools:
270			http://www.objectsbydesign.com/tools/umltools_byPrice.html
271
272			Further readings:
273			http://www.google.com/search?q=web+based+uml+editor&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=10&sa=N
274			http://www.fernuni-hagen.de/DVT/Aktuelles/01FHHeidelberg.pdf
275			http://www.enhyper.com/src/documentation/
276			http://cis.cs.tu-berlin.de/Dokumente/Diplomarbeiten/2001/skinner.pdf
277			http://citeseer.nj.nec.com/vilain00diagrammatic.html
278			http://archive.devx.com/uml/articles/Smith01/Smith01-3.asp
279
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