| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" |
| 2 | "http://www.w3.org/TR/html4/loose.dtd"> |
| 3 | <html> |
| 4 | <head> |
| 5 | <title>Libxml Catalog support</title> |
| 6 | <meta name="GENERATOR" content="amaya V5.0"> |
| 7 | <meta http-equiv="Content-Type" content="text/html"> |
| 8 | </head> |
| 9 | |
| 10 | <body bgcolor="#ffffff"> |
| 11 | <h1 align="center">Libxml Catalog support</h1> |
| 12 | |
| 13 | <p>Location: <a |
| 14 | href="http://xmlsoft.org/catalog.html">http://xmlsoft.org/catalog.html</a></p> |
| 15 | |
| 16 | <p>Libxml home page: <a href="http://xmlsoft.org/">http://xmlsoft.org/</a></p> |
| 17 | |
| 18 | <p>Mailing-list archive: <a |
| 19 | href="http://mail.gnome.org/archives/xml/">http://mail.gnome.org/archives/xml/</a></p> |
| 20 | |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 21 | <p>Version: $Revision: 1.1 $</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 22 | |
| 23 | <p>Table of Content:</p> |
| 24 | <ol> |
| 25 | <li><a href="#General">General overview</a></li> |
| 26 | <li><a href="#definition">The definition</a></li> |
| 27 | <li><a href="#Simple">Using catalogs</a></li> |
| 28 | <li><a href="#Some">Some examples</a></li> |
| 29 | <li><a href="#reference">How to tune catalog usage</a></li> |
| 30 | <li><a href="#validate">How to debug catalog processing</a></li> |
| 31 | <li><a href="#Declaring">How to create and maintain catalogs</a></li> |
| 32 | <li><a href="#implemento">The implementor corner quick review of the |
| 33 | API</a></li> |
| 34 | <li><a href="#Other">Other resources</a></li> |
| 35 | </ol> |
| 36 | |
| 37 | <h2><a name="General">General overview</a></h2> |
| 38 | |
| 39 | <p>What is a catalog ? Basically it's a lookup mechanism which is used when |
| 40 | an entity (a file or a remote resource) reference another entity. The catalog |
| 41 | lookup is inserted between the moment the reference is recognized by the |
| 42 | software (XML parser, stylesheet processing, or even images referenced for |
| 43 | inclusion in a rendering) and the time where loading that resource is |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 44 | actually started.</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 45 | |
| 46 | <p>It is basically used for 3 things:</p> |
| 47 | <ul> |
| 48 | <li>mapping from "logical" names, the public identifiers and a more |
| 49 | concrete name usable for download (and URI). For example it can associate |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 50 | the logical name |
| 51 | <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 52 | <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be |
| 53 | downloaded</p> |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 54 | <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 55 | </li> |
| 56 | <li>remapping from a given URL to another one, like an HTTP indirection |
| 57 | saying that |
| 58 | <p>"http://www.oasis-open.org/committes/tr.xsl"</p> |
| 59 | <p>should really be looked at</p> |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 60 | <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 61 | </li> |
| 62 | <li>providing a local cache mechanism allowing to load the entities |
| 63 | associated to public identifiers or remote resources, this is a really |
| 64 | important feature for any significant deployment of XML or SGML since it |
| 65 | allows to avoid the aleas and delays associated to fetching remore |
| 66 | resources.</li> |
| 67 | </ul> |
| 68 | |
| 69 | <h2><a name="definition">The definitions</a></h2> |
| 70 | |
| 71 | <p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p> |
| 72 | <ul> |
| 73 | <li>the older SGML catalogs, the official spec is SGML Open Technical |
| 74 | Resolution TR9401:1997, but is better understood by reading <a |
| 75 | href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from |
| 76 | James Clark. This is relatively old and not the preferred mode of |
| 77 | operation of libxml.</li> |
| 78 | <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 79 | Catalogs</a> |
| 80 | is far more flexible, more recent, uses an XML syntax and should scale |
| 81 | quite better. This is the default option of libxml.</li> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 82 | </ul> |
| 83 | |
| 84 | <p></p> |
| 85 | |
| 86 | <h2><a name="Simple">Using catalog</a></h2> |
| 87 | |
| 88 | <p>In a normal environment libxml will by default check the presence of a |
| 89 | catalog in /etc/xml/catalog, and assuming it has been correctly populated, |
| 90 | the processing is completely transparent to the document user. To take a |
| 91 | concrete example, suppose you are authoring a DocBook document, this one |
| 92 | starts with the following DOCTYPE definition:</p> |
| 93 | <pre><?xml version='1.0'?> |
| 94 | <!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" |
| 95 | "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 96 | </pre> |
| 97 | |
| 98 | <p>When validating the document with libxml, the catalog will be |
| 99 | automatically consulted to lookup the public identifier "-//Norman Walsh//DTD |
| 100 | DocBk XML V3.1.4//EN" and the system identifier |
| 101 | "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have |
| 102 | been installed on your system and the catalogs actually point to them, libxml |
| 103 | will fetch them from the local disk.</p> |
| 104 | |
| 105 | <p style="font-size: 10pt"><strong>Note</strong>: Really don't use this |
| 106 | DOCTYPE example it's a really old version, but is fine as an example.</p> |
| 107 | |
| 108 | <p>Libxml will check the catalog each time that it is requested to load an |
| 109 | entity, this include DTD, external parsed entities, stylesheets, etc ... If |
| 110 | your system is correctly configured all the authoring phase and processing |
| 111 | should use only local files, even if your document stay portable because it |
| 112 | uses the canonical public and system ID, referencing the remote document.</p> |
| 113 | |
| 114 | <h2><a name="Some">Some examples:</a></h2> |
| 115 | |
| 116 | <p>Here is a couple of fragments from XML Catalogs used in libxml early |
| 117 | regression tests in <code>test/catalogs</code> :</p> |
| 118 | <pre><?xml version="1.0"?> |
| 119 | <!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" |
| 120 | "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> |
| 121 | <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> |
| 122 | <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 123 | uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> |
| 124 | ...</pre> |
| 125 | |
| 126 | <p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are |
| 127 | written in XML, there is a specific namespace for catalog elements |
| 128 | "urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this |
| 129 | catalog is a <code>public</code> mapping it allows to associate a Public |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 130 | Identifier with an URI.</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 131 | <pre>... |
| 132 | <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" |
| 133 | rewritePrefix="file:///usr/share/xml/docbook/"/> |
| 134 | ...</pre> |
| 135 | |
| 136 | <p>A <code>rewriteSystem</code> is a very powerful instruction, it says that |
| 137 | any URI starting with a given prefix should be looked at another URI |
| 138 | constructed by replacing the prefix with an new one. In effect this acts like |
| 139 | a cache system for a full area of the Web. In practice it is extremely useful |
| 140 | with a file prefix if you have installed a copy of those resources on your |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 141 | local system.</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 142 | <pre>... |
| 143 | <delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" |
| 144 | catalog="file:///usr/share/xml/docbook.xml"/> |
| 145 | <delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" |
| 146 | catalog="file:///usr/share/xml/docbook.xml"/> |
| 147 | <delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" |
| 148 | catalog="file:///usr/share/xml/docbook.xml"/> |
| 149 | <delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" |
| 150 | catalog="file:///usr/share/xml/docbook.xml"/> |
| 151 | <delegateURI uriStartString="http://www.oasis-open.org/docbook/" |
| 152 | catalog="file:///usr/share/xml/docbook.xml"/> |
| 153 | ...</pre> |
| 154 | |
| 155 | <p>Delegation is the core features which allows to build a tree of catalogs, |
| 156 | easier to maintain than a single catalog, based on Public Identifier, System |
| 157 | Identifier or URI prefixes it instruct the catalog software to lookup entries |
| 158 | in another resource. This feature allow to build hierarchies of catalogs, the |
| 159 | set of entries presented should be sufficient to redirect the resolution of |
| 160 | all DocBook references to the specific catalog in |
| 161 | <code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all |
| 162 | references for DocBook 4.2.1 to a specific catalog installed at the same time |
| 163 | as the DocBook resources on the local machine.</p> |
| 164 | |
| 165 | <h2><a name="reference">How to tune catalog usage:</a></h2> |
| 166 | |
| 167 | <p>The user can change the default catalog behaviour by redirecting queries |
| 168 | to its own set of catalogs, this can be done by setting the |
| 169 | <code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an |
| 170 | empty one should desactivate loading the default |
| 171 | <code>/etc/xml/catalog</code> default catalog.</p> |
| 172 | |
| 173 | <p>@@More options are likely to be provided in the future@@</p> |
| 174 | |
| 175 | <h2><a name="validate">How to debug catalog processing:</a></h2> |
| 176 | |
| 177 | <p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will |
| 178 | make libxml output debugging informations for each catalog operations, for |
| 179 | example:</p> |
| 180 | <pre>orchis:~/XML -> xmllint --memory --noout test/ent2 |
| 181 | warning: failed to load external entity "title.xml" |
| 182 | orchis:~/XML -> export XML_DEBUG_CATALOG= |
| 183 | orchis:~/XML -> xmllint --memory --noout test/ent2 |
| 184 | Failed to parse catalog /etc/xml/catalog |
| 185 | Failed to parse catalog /etc/xml/catalog |
| 186 | warning: failed to load external entity "title.xml" |
| 187 | Catalogs cleanup |
| 188 | orchis:~/XML -> </pre> |
| 189 | |
| 190 | <p>The test/ent2 references an entity, running the parser from memory makes |
| 191 | the base URI unavailable and the the "title.xml" entity cannot be loaded. |
| 192 | Setting up the debug environment variable allows to detect that an attempt is |
| 193 | made to load the <code>/etc/xml/catalog</code> but since it's not present the |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 194 | resolution fails.</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 195 | |
| 196 | <p>But the most advanced way to debug XML catalog processing is to use the |
| 197 | <strong>xmlcatalog</strong> command shipped with libxml2, it allows to load |
| 198 | catalogs and make resolution queries to see what is going on. This is also |
| 199 | used for the regression tests:</p> |
| 200 | <pre>orchis:~/XML -> ./xmlcatalog test/catalogs/docbook.xml "-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 201 | http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd |
| 202 | orchis:~/XML -> </pre> |
| 203 | |
| 204 | <p>For debugging what is going on, adding one -v flags increase the verbosity |
| 205 | level to indicate the processing done (adding a second flag also indicate |
| 206 | what elements are recognized at parsing):</p> |
| 207 | <pre>orchis:~/XML -> ./xmlcatalog -v test/catalogs/docbook.xml "-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 208 | Parsing catalog test/catalogs/docbook.xml's content |
| 209 | Found public match -//OASIS//DTD DocBook XML V4.1.2//EN |
| 210 | http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd |
| 211 | Catalogs cleanup |
| 212 | orchis:~/XML -> </pre> |
| 213 | |
| 214 | <p>A shell interface is also available to debug and process multiple queries |
| 215 | (and for regression tests):</p> |
| 216 | <pre>orchis:~/XML -> ./xmlcatalog -shell test/catalogs/docbook.xml "-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 217 | > help |
| 218 | Commands available: |
| 219 | public PublicID: make a PUBLIC identifier lookup |
| 220 | system SystemID: make a SYSTEM identifier lookup |
| 221 | resolve PublicID SystemID: do a full resolver lookup |
| 222 | add 'type' 'orig' 'replace' : add an entry |
| 223 | del 'values' : remove values |
| 224 | dump: print the current catalog state |
| 225 | debug: increase the verbosity level |
| 226 | quiet: decrease the verbosity level |
| 227 | exit: quit the shell |
| 228 | > public "-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 229 | http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd |
| 230 | > quit |
| 231 | orchis:~/XML -> </pre> |
| 232 | |
| 233 | <p>This should be sufficient for most debugging purpose, this was actually |
| 234 | used heavilly to debug the XML Catalog implementation itself.</p> |
| 235 | |
| 236 | <h2><a name="Declaring">How to create and maintain</a> catalogs:</h2> |
| 237 | |
| 238 | <p>Basically XML Catalogs are XML files, you can either use XML tools to |
| 239 | manage them or use <strong>xmlcatalog</strong> for this. The basic step is |
| 240 | to create a catalog the -create option provide this facility:</p> |
| 241 | <pre>orchis:~/XML -> ./xmlcatalog --create tst.xml |
| 242 | <?xml version="1.0"?> |
| 243 | <!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" |
| 244 | "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> |
| 245 | <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> |
| 246 | orchis:~/XML -> </pre> |
| 247 | |
| 248 | <p>By default xmlcatalog does not overwrite the original catalog and save the |
| 249 | result on the standard output, this can be overrident using the -noout |
| 250 | option. The <code>-add</code> command allows to add entries in the |
| 251 | catalog:</p> |
| 252 | <pre>orchis:~/XML -> ./xmlcatalog --noout --create --add "public" "-//OASIS//DTD DocBook XML V4.1.2//EN" http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml |
| 253 | orchis:~/XML -> cat tst.xml |
| 254 | <?xml version="1.0"?> |
| 255 | <!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> |
| 256 | <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> |
| 257 | <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" |
| 258 | uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> |
| 259 | </catalog> |
| 260 | orchis:~/XML -> </pre> |
| 261 | |
| 262 | <p>The <code>-add</code> option will always take 3 parameters even if some of |
| 263 | the XML Catalog constructs (like nextCatalog) will have only a single |
| 264 | argument, just pass a third empty string, it will be ignored.</p> |
| 265 | |
| 266 | <p>Similary the <code>-del</code> option remove matching entries from the |
| 267 | catalog:</p> |
| 268 | <pre>orchis:~/XML -> ./xmlcatalog --del "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml |
| 269 | <?xml version="1.0"?> |
| 270 | <!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> |
| 271 | <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> |
| 272 | orchis:~/XML -> </pre> |
| 273 | |
| 274 | <p>The catalog is now empty. Note that the maching of <code>-del</code> is |
| 275 | exact and would have worked in a similar fashion with the Public ID |
| 276 | string.</p> |
| 277 | |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 278 | <p>This is rudimentary but should be sufficient to manage a not too complex |
| 279 | catalog tree of resources.</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 280 | |
| 281 | <h2><a name="implemento">The implementor corner quick review of the |
| 282 | API:</a></h2> |
| 283 | |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 284 | <p>First an like for every other module of libxml, there is an automatically |
| 285 | generated <a href="html/libxml-catalog.html">API page for catalog |
| 286 | support</a>.</p> |
| 287 | |
| 288 | <p>The header for the catalog interfaces should be included as:</p> |
| 289 | <pre>#include <libxml/catalog.h></pre> |
| 290 | |
| 291 | <p>The API is voluntarily kept very simple. First it is not obvious that |
| 292 | applications really need access to it since it is the default behaviour of |
| 293 | libxml (Note: it is possible to completely override libxml default catalog by |
| 294 | using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to |
| 295 | plug an application specific resolver).</p> |
| 296 | |
| 297 | <p>Basically libxml support 2 catalog lists:</p> |
| 298 | <ul> |
| 299 | <li>the default one, global shared by all the application</li> |
| 300 | <li>a per-document catalog, this one is built if the document uses the |
| 301 | <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is |
| 302 | associated to the parser context and destroyed when the parsing context |
| 303 | is destroyed.</li> |
| 304 | </ul> |
| 305 | |
| 306 | <p>the document one will be used first if it exists.</p> |
| 307 | |
| 308 | <h3>Initialization routines:</h3> |
| 309 | |
| 310 | <p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be |
| 311 | used at startup to initialize the catalog, if the catalog should be |
| 312 | initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() |
| 313 | should be called before xmlInitializeCatalog() which would otherwise do a |
| 314 | default initialization first.</p> |
| 315 | |
| 316 | <p>The xmlCatalogAddLocal() call is used by the parser to grow the document |
| 317 | own catalog list if needed.</p> |
| 318 | |
| 319 | <h3>Preferences setup:</h3> |
| 320 | |
| 321 | <p>The XML Catalog spec requires the possibility to select default |
| 322 | preferences between public and system delegation, |
| 323 | xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and |
| 324 | xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should |
| 325 | be forbidden, allowed for global catalog, for document catalog or both, the |
| 326 | default is to allow both.</p> |
| 327 | |
| 328 | <p>And of course xmlCatalogSetDebug() allows to generate debug messages |
| 329 | (through the xmlGenericError() mechanism).</p> |
| 330 | |
| 331 | <h3>Querying routines:</h3> |
| 332 | |
| 333 | <p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() |
| 334 | and xmlCatalogResolveURI() are relatively explicit if you read the XML |
| 335 | Catalog specification they correspond to section 7 algorithms, they should |
| 336 | also work if you have loaded an SGML catalog with a simplified semantic.</p> |
| 337 | |
| 338 | <p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but |
| 339 | operate on the document catalog list</p> |
| 340 | |
| 341 | <h3>Cleanup and Miscellaneous:</h3> |
| 342 | |
| 343 | <p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is |
| 344 | the per-document equivalent.</p> |
| 345 | |
| 346 | <p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the |
| 347 | first catalog in the global list, and xmlCatalogDump() allows to dump a |
| 348 | catalog state, those routines are primarily designed for xmlcatalog, I'm not |
| 349 | sure that exposing more complex interfaces (like navigation ones) would be |
| 350 | really useful.</p> |
| 351 | |
| 352 | <h3>threaded environments:</h3> |
| 353 | |
| 354 | <p>Since the catalog tree is built progressively, some care has been taken to |
| 355 | try to avoid troubles in multithreaded environments but without a |
| 356 | test-and-set routine accessible from C this can't be fully garanteed, so the |
| 357 | best is to use xmlGetExternalEntityLoader and set the entity loader routines |
| 358 | to one of your code doing the synchronization.</p> |
| 359 | |
| 360 | <p></p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 361 | |
| 362 | <h2><a name="Other">Other resources</a></h2> |
| 363 | |
| 364 | <p>The XML Catalog specification is relatively recent so there isn't much |
| 365 | litterature to point at:</p> |
| 366 | <ul> |
| 367 | <li>You can find an good rant from Norm Walsh about <a |
| 368 | href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the |
| 369 | need for catalogs</a>, it provides a lot of context informations even if |
| 370 | I don't agree with everything presented.</li> |
| 371 | <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML |
| 372 | catalog proposal</a> from John Cowan</li> |
| 373 | <li>The <a href="http://www.rddl.org/">Resource Directory Description |
| 374 | Language</a> (RDDL) another catalog system but more oriented toward |
| 375 | providing metadata for XML namespaces.</li> |
| 376 | <li>the page from the OASIS Technical <a |
| 377 | href="http://www.oasis-open.org/committees/entity/">Committee on Entity |
| 378 | Resolution</a> who maintains XML Catalog, you will find pointers to the |
| 379 | specification update, some background and pointers to others tools |
| 380 | providing XML Catalog support</li> |
| 381 | </ul> |
| 382 | |
| 383 | <p>If you have suggestions for corrections or additions, simply contact |
| 384 | me:</p> |
| 385 | |
| 386 | <p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p> |
| 387 | |
| Daniel Veillard | ffb120d | 2001-08-23 00:52:23 +0000 | [diff] [blame^] | 388 | <p>$Id: catalog.html,v 1.1 2001/08/22 23:44:08 veillard Exp $</p> |
| Daniel Veillard | e7ead2d | 2001-08-22 23:44:09 +0000 | [diff] [blame] | 389 | </body> |
| 390 | </html> |