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Contents of /nfo/perl/libs/Data/Storage.pod

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Revision 1.3 - (show annotations)
Tue May 13 07:00:33 2003 UTC (21 years, 1 month ago) by joko
Branch: MAIN
Changes since 1.2: +9 -0 lines
updated

1 =pod
2
3
4 =head1 NAME
5
6 Data::Storage - Interface for accessing various Storage implementations for Perl in an independent way
7
8
9 =head1 AIMS
10
11 - should encapsulate Tangram, DBI, DBD::CSV and LWP:: to access them in an unordinary (more convenient) way ;)
12 - introduce a generic layered structure, refactor *SUBLAYER*-stuff, make (e.g.) this possible:
13 Perl Data::Storage[DBD::CSV] -> Perl LWP:: -> Internet HTTP/FTP/* -> Host Daemon -> csv-file
14 - provide generic synchronization mechanisms across arbitrary/multiple storages based on ident/checksum
15 maybe it's possible to have schema-, structural- and semantical modifications synchronized???
16
17
18 =head1 SYNOPSIS
19
20 =head2 ACCESS
21
22 # connect to LDAP
23 my $ldapLocator = Data::Storage::Locator->new(
24 ldap => {
25 type => "NetLDAP",
26 dsn => "ldap:host=192.168.10.150;binddn='cn=root, o=netfrag.org, c=de';pass=secret",
27 basedn => "o=netfrag.org, c=de",
28 want_transactions => 0,
29 syncable => 1,
30 },
31 );
32 my $ldapStorage = Data::Storage->new($ldapLocator);
33 $ldapStorage->connect();
34
35 # connect to MAPI
36 my $mapiLocator = Data::Storage::Locator->new(
37 outlook => {
38 type => "MAPI",
39 showProfileChooser => $self->{config}->get("mapi_showProfileChooser"),
40 ProfileName => $self->{config}->get("mapi_ProfileName"),
41 ProfilePass => $self->{config}->get("mapi_ProfilePass"),
42 syncable => 1,
43 },
44 );
45 my $mapiStorage = Data::Storage->new($mapiLocator);
46 $mapiStorage->connect();
47
48
49 =head2 SYNCHRONIZATION
50
51 This functionality is (in the meanwhile) provided by the Data::Transfer::Sync module.
52
53 =head3 proposal V1
54
55 my $nodemapping = {
56 'LangText' => 'langtexts.csv',
57 'Currency' => 'currencies.csv',
58 'Country' => 'countries.csv',
59 };
60
61 my $propmapping = {
62 'LangText' => [
63 [ 'source:lcountrykey' => 'target:country' ],
64 [ 'source:lkey' => 'target:key' ],
65 [ 'source:lvalue' => 'target:text' ],
66 ],
67 'Currency' => [
68 [ 'source:ckey' => 'target:key' ],
69 [ 'source:cname' => 'target:text' ],
70 ],
71 'Country' => [
72 [ 'source:ckey' => 'target:key' ],
73 [ 'source:cname' => 'target:text' ],
74 ],
75 };
76
77 s ub syncResource {
78
79 my $self = shift;
80 my $node_source = shift;
81 my $mode = shift;
82 my $opts = shift;
83
84 $mode ||= '';
85 $opts->{erase} ||= 0;
86
87 $logger->info( __PACKAGE__ . "->syncResource( node_source $node_source mode $mode erase $opts->{erase} )");
88
89 # resolve metadata for syncing requested resource
90 my $node_target = $nodemapping->{$node_source};
91 my $mapping = $propmapping->{$node_source};
92
93 if (!$node_target || !$mapping) {
94 # loggger.... "no target, sorry!"
95 print "error while resolving resource metadata", "\n";
96 return;
97 }
98
99 if ($opts->{erase}) {
100 $self->_erase_all($node_source);
101 }
102
103 # create new sync object
104 my $sync = Data::Transfer::Sync->new(
105 storages => {
106 L => $self->{storage}->{backend},
107 R => $self->{storage}->{resources},
108 },
109 id_authorities => [qw( L ) ],
110 checksum_authorities => [qw( L ) ],
111 write_protected => [qw( R ) ],
112 verbose => 1,
113 );
114
115 # sync
116 # todo: filter!?
117 $sync->syncNodes( {
118 direction => $mode, # | +PUSH | +PULL | -FULL | +IMPORT | -EXPORT
119 method => 'checksum', # | -timestamp | -manual
120 source => "L:$node_source",
121 source_ident => 'storage_method:id',
122 source_exclude => [qw( id cs )],
123 target => "R:$node_target",
124 target_ident => 'property:oid',
125 mapping => $mapping,
126 } );
127
128 }
129
130 =head3 proposal V2
131
132 # create a new synchronization object
133 my $sync = Data::Transfer::Sync->new( 'sync_version' => $sync_version, __parent => $self );
134
135 # configure the synchronization-object
136 $sync->configure(
137 source => {
138 storage => {
139 handle => $mapiStorage,
140 #isIdentAuthority => 1,
141 #isChecksumAuthority => 1,
142 #writeProtected => 1,
143 },
144 },
145 target => {
146 storage => {
147 handle => $ldapStorage,
148 #idAuthority => 1,
149 #isChecksumAuthority => 1,
150 #isWriteProtected => 0,
151 },
152 },
153 verbose => 1,
154 );
155
156
157 =head2 NOTE
158
159 This module heavily relies on DBI and Tangram, but adds a lot of additional bugs and quirks.
160 Please look at their documentation and/or this code for additional information.
161
162
163 =head1 REQUIREMENTS
164
165 For full functionality:
166 DBI from CPAN
167 DBD::mysql from CPAN
168 Tangram 2.04 from CPAN (hmmm, 2.04 won't do in some cases)
169 Tangram 2.05 from http://... (2.05 seems okay but there are also additional patches from our side)
170 Class::Tangram from CPAN
171 DBD::CSV from CPAN
172 MySQL::Diff from http://adamspiers.org/computing/mysqldiff/
173 ... and all their dependencies
174
175
176 =head1 DESCRIPTION
177
178 =head2 Data::Storage
179
180 Data::Storage is a module for accessing various "data structures / kinds of structured data" stored inside
181 various "data containers".
182 We tried to use the AdapterPattern to implement a wrapper-layer around known CPAN modules.
183 (e.g. DBI, Tangram, XML::Simple)
184 References:
185 - http://c2.com/cgi/wiki?AdapterPattern
186 - http://home.earthlink.net/~huston2/dp/adapter.html
187
188 =head2 Why?
189
190 You will get a better code-structure (not bad for later maintenance) in growing Perl code projects,
191 especially when using multiple database connections at the same time.
192 You will be able to switch between different _kinds_ of implementations used for storing data.
193 Your code will use the very same API to access these storage layers.
194 ... implementation has to be changed for now
195 Maybe you will be able to switch "on-the-fly" without changing any bits in code in the future....
196 ... but that's not the focus
197
198 =head2 What else?
199
200 Having this, we were able to do implement a generic data synchronization module more easy,
201 please look at Data::Transfer.
202
203
204 =head1 AUTHORS / COPYRIGHT
205
206 The Data::Storage module is Copyright (c) 2002 Andreas Motl.
207 All rights reserved.
208 You may distribute it under the terms of either the GNU General Public
209 License or the Artistic License, as specified in the Perl README file.
210
211
212 =head1 ACKNOWLEDGEMENTS
213
214 Larry Wall for Perl, Tim Bunce for DBI, Jean-Louis Leroy for Tangram and Set::Object,
215 Sam Vilain for Class::Tangram, Jochen Wiedmann and Jeff Zucker for DBD::CSV & Co.,
216 Adam Spiers for MySQL::Diff and all contributors.
217
218
219 =head1 SUPPORT / WARRANTY
220
221 Data::Storage is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.
222
223
224 =head1 TODO
225
226 o interface with Jeff Zucker's AnyData:: modules, e.g. AnyData::Storage::RAM
227 o what about DBD::RAM? (DBD::RAM - a DBI driver for files and data structures)
228 o use DBD::Proxy!
229 o what about DBIx::AnyDBD?
230 o enhance schema information:
231 - DBIx::SystemCatalog
232 - DBIx::SystemCatalog::MSSQL?
233 - Data::Reporter
234
235
236 =head2 BUGS
237
238 "DBI-Error [Tangram]: DBD::mysql::st execute failed: Unknown column 't1.requestdump' in 'field list'"
239
240 ... occours when operating on object-attributes not introduced yet:
241 this should be detected and appended/replaced through:
242 "Schema-Error detected, maybe (just) an inconsistency.
243 Please check if your declaration in schema-module "a" matches structure in database "b" or try to run"
244 db_setup.pl --dbkey=import --action=deploy
245
246
247 Compare schema (structure diff) with database ...
248
249 ... when issuing "db_setup.pl --dbkey=import --action=deploy"
250 on a database with an already deployed schema, use an additional "--update" then
251 to lift the schema inside the database to the current declared schema.
252 You will have to approve removals and changes on field-level while
253 new objects and new fields are introduced silently without any interaction needed.
254 In future versions there may be additional options to control silent processing of
255 removals and changes.
256 See this CRUD-table applying to the actions occouring on Classes and Class variables when deploying schemas,
257 don't mix this up with CRUD-actions on Objects, these are already handled by (e.g.) Tangram itself.
258 Classes:
259 C create -> yes, handled automatically
260 R retrieve -> no, not subject of this aspect since it is about deployment only
261 U update -> yes, automatically for Class meta-attributes, yes/no for Class variables (look at the rules down here)
262 D delete -> yes, just by user-interaction
263 Class variables:
264 C create -> yes, handled automatically
265 R retrieve -> no, not subject of this aspect since it is about deployment only
266 U update -> yes, just by user-interaction; maybe automatically if it can be determined that data wouldn't be lost
267 D delete -> yes, just by user-interaction
268
269 It's all about not to be able to loose data simply while this is in pre-alpha stage.
270 And loosing data by being able to modify and redeploy schemas easily is definitely quite easy.
271
272 As we can see, creations of Classes and new Class variables is handled
273 automatically and this is believed to be the most common case under normal circumstances.
274
275
276 =head2 FEATURES
277
278 - Get this stuff together with UML (Unified Modeling Language) and/or standards from ODMG.
279 - Make it possible to load/save schemas in XMI (XML Metadata Interchange),
280 which seems to be most commonly used today, perhaps handle objects with OIFML.
281 Integrate/bundle this with a web-/html-based UML modeling tool or
282 some other interesting stuff like the "Co-operative UML Editor" from Uni Darmstadt. (web-/java-based)
283 - Enable Round Trip Engineering. Keep code and diagrams in sync. Don't annoy/bother the programmers.
284 - Add support for some more handlers/locators to be able to
285 access the following standards/protocols/interfaces/programs/apis transparently:
286 + DBD::CSV (via Data::Storage::Handler::DBI)
287 (-) Text::CSV, XML::CSV, XML::Excel
288 - MAPI
289 - LDAP
290 - DAV (look at PerlDAV: http://www.webdav.org/perldav/)
291 - Mbox (use formail for seperating/splitting entries/nodes)
292 - Cyrus (cyrdeliver - what about cyrretrieve (export)???)
293 - use File::DiffTree, use File::Compare
294 - Hibernate
295 - "Win32::UserAccountDb"
296 - "*nix::UserAccountDb"
297 - .wab - files (Windows Address Book)
298 - .pst - files (Outlook Post Storage?)
299 - XML (e.g. via XML::Simple?)
300 - Move to t3, look at InCASE
301 - some kind of security layer for methods/objects
302 - acls (stored via tangram/ldap?) for functions, methods and objects (entity- & data!?)
303 - where are the hooks needed then?
304 - is Data::Storage & Co. okay, or do we have to touch the innards of DBI and/or Tangram?
305 - an attempt to start could be:
306 - 'sub getACLByObjectId($id, $context)'
307 - 'sub getACLByMethodname($id, $context)'
308 - 'sub getACLByName($id, $context)'
309 ( would require a kinda registry to look up these very names pointing to arbitrary locations (code, data, ...) )
310 - add more hooks and various levels
311 - better integrate introduced 'getObjectByGuid'-mechanism from Data::Storage::Handler::Tangram
312
313
314 =head3 LINKS / REFERENCES
315
316 Specs:
317 UML 1.3 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-06-08.pdf
318 XMI 1.1 Spec: http://cgi.omg.org/cgi-bin/doc?ad/99-10-02.pdf
319 XMI 2.0 Spec: http://cgi.omg.org/docs/ad/01-06-12.pdf
320 ODMG: http://odmg.org/
321 OIFML: http://odmg.org/library/readingroom/oifml.pdf
322
323 CASE Tools:
324 Rational Rose (commercial): http://www.rational.com/products/rose/
325 Together (commercial): http://www.oi.com/products/controlcenter/index.jsp
326 InCASE - Tangram-based Universal Object Editor
327 Sybase PowerDesigner: http://www.sybase.com/powerdesigner
328
329 UML Editors:
330 Fujaba (free, university): http://www.fujaba.de/
331 ArgoUML (free): http://argouml.tigris.org/
332 Poseidon (commercial): http://www.gentleware.com/products/poseidonDE.php3
333 Co-operative UML Editor (research): http://www.darmstadt.gmd.de/concert/activities/internal/umledit.html
334 Metamill (commercial): http://www.metamill.com/
335 Violet (university, research, education): http://www.horstmann.com/violet/
336 PyUt (free): http://pyut.sourceforge.net/
337 (Dia (free): http://www.lysator.liu.se/~alla/dia/)
338 UMLet (free, university): http://www.swt.tuwien.ac.at/umlet/index.html
339 Voodoo (free): http://voodoo.sourceforge.net/
340 Umbrello UML Modeller: http://uml.sourceforge.net/
341
342 UML Tools:
343 http://www.objectsbydesign.com/tools/umltools_byPrice.html
344
345 Further readings:
346 http://www.google.com/search?q=web+based+uml+editor&hl=en&lr=&ie=UTF-8&oe=UTF-8&start=10&sa=N
347 http://www.fernuni-hagen.de/DVT/Aktuelles/01FHHeidelberg.pdf
348 http://www.enhyper.com/src/documentation/
349 http://cis.cs.tu-berlin.de/Dokumente/Diplomarbeiten/2001/skinner.pdf
350 http://citeseer.nj.nec.com/vilain00diagrammatic.html
351 http://archive.devx.com/uml/articles/Smith01/Smith01-3.asp
352
353
354 =cut
355

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