RDF API Draft (original) (raw)
Current revision: 2001-01-19
- Overview
- Known use cases
- Download and revision history
- Documentation (most recent release)
- Ant build script for source code contributed by David Li (DigitalSesame.com)
- FAQ (incomplete)
- Tutorial (under construction)
- Examples
- Creating unique URIs
- Vocabulary class generator
- Cryptographic digests of RDF models and statements
- UML on top of RDF (code included in this distribution)
- Feedback
Overview
This is a draft of an RDF API provided for a public discussion. The API defines interfaces for parsing (org.w3c.rdf.syntax) and accessing RDF models as sets of statements (org.w3c.rdf.model). Default implementations for those interfaces are included in the org.w3c.rdf.implementation package.
There are additional modules in the distribution that do not belong to the core API. They are packaged with the API to simplify download and evaluation:
- Since May 12, 2000 the distribution includes
- support for UML over RDF
- a tool for generating classes with Java "constants" for simplified manipulation of schemas (edu.stanford.db.rdf.vocabulary.Generator, details here)
- Since Dec 16, 1999 the distribution includes a parser for a simplified syntax for RDF. See "Briding the Gap between RDF and XML" and "Simplified Syntax for RDF" for more details.
Known use cases
- Prot�g� 2000 by Stanford Medical Informatics
- Promenade RDF Parser by Profium
- FRODO RDFSViz by DFKI Kaiserslautern
- OntoEdit by AIFB Karlsruhe University / OntoPrise
- Interdataworking Converter by Stanford OntoAgents
- CIMValidate by Arnold deVos (Langdale Consultants)
- DAMLJessKB by Joe Kopena Please let me know about further uses.
Download and revision history
.zip files contain documentation, sources and the jar file.
| 2001-01-19 | Download: <rdf-api-2001-01-19.zip> (jarfile only) Optimization release. Speed-up by an order of magnitude when dealing with large models. Provided a more efficient implementation of interfaces in org.w3c.rdf.model (i.e. resources, statements, models etc.) The new implementation is contained in package edu.stanford.db.rdf.model.i and is used as the default one in examples and org.w3c.rdf.util.RDFFactoryImpl. Make sure you switch to the new implementation if you were using org.w3c.rdf.implementation.model classes directly (e.g. not via RDFFactory) in your code! Added a new pair of parser/serializer: edu.stanford.db.rdf.syntax.generic.{TripleSerializer|TripleParser}. These are stream-oriented tools that are based on an extremely simple XML-based serialization syntax. The parser/serializer are very fast and small, and support a compact reification syntax. Use them e.g. for on-the-wire exchange of RDF models.Better namespace support: added capability of overriding the default way the namespace abbreviations are generated in the serializer SiRS. Added a group of methods collectNamespaces in org.w3c.rdf.util.RDFUtil (suggested by Michael Sintek).Fixed bug in saving of models in RDFUtil (uncovered by Michael Sintek).Added method getNodeFactory to RDFFactory. |
|---|---|
| 2000-12-05 | Download: <rdf-api-2000-12-05.zip> (jarfile only) Bugfix release. Made digest computation in the default resource/literal/model implementation more efficientImplemented syntax in edu.stanford.db.rdf.syntax.generic.TripleSerializer. Now it supports reification and embedded models efficientlySiRS: fixed "order"-related bug; revived abbreviated syntax; improved efficiencySiRPAC: added a function to disable fetching of external entities in XML parser; fixed bug with empty name in input source |
| 2000-11-13 | Download: <rdf-api-2000-11-13.zip> (jarfile only) This release contains a major package restructuring; the org.w3c.rdf subtree has been cleaned up, a few packages have been moved to edu.stanford tree. The API interfaces are not affected. In addition, this release provides several fixes and improvements. Moved org.w3c.rdf.util.xml to edu.stanford.db.xml.util and edu.stanford.db.rdf.syntax.generic Moved org.w3c.rdf.implementation.syntax.strawman to edu.stanford.db.rdf.syntax.strawman Moved org/w3c/rdf/examples/StrawmanToMS10.java to edu/stanford/db/rdf/examples/StrawmanToMS10.java Modified SiRPAC to reflect changesMoved digest utilities from org/w3c/rdf/util/ to org/w3c/rdf/digest/ Trashed org/w3c/rdf/util/OrderUtil.java, org/w3c/rdf/util/OrderedModel.java Trashed org/w3c/tools completelyGenerated an updated schema vocabulary org/w3c/rdf/vocabulary/rdf_schema_200001/RDFS.java Generated a schema vocabulary for DAML-O: edu/stanford/db/rdf/vocabulary/daml_o_20001011/DAML_O.java Fixed a bug in SiRS serializer which could not deal with more than 26 namespaces (reported by Mike Dean).Modified the digest algorithm for models as suggested by Steve Dunham. The algorithm is now cryptographically secure. |
| 2000-10-30 | Download: <rdf-api-2000-10-30.zip> (jarfile only) Notice: this release contains (incremental) changes to the API that are not backward compatible! Now resources support methods getNamespace() and getLocalName(). This change affected several other interfaces.Changed NodeFactory interface: allow namespace-based resource creationChanged ModelImpl (fixed bug in duplication of models)Added getName and getNamespace to RDFUtil Extended NodeFactory to createLiterals for all primitive Java types: boolean, byte, short, char, int, long, float, doubleModified NodeFactory implementation to speedup secure random generationFixed a bug in SiRS related to empty namespacesParseAndSerialize accepts options -xml and -triples Moved experimental order resources to a separate class (edu.stanford.db.rdf.vocabulary.order_20000527) and changed SiRPAC and SiRS adequately.Added more reserved words to edu.stanford.db.rdf.vocabulary.Generator SiRPAC now recognizes unqualified ID, resource and about XML attributes. It also supports new namespace handling and deals with string generation in a slightly more efficient way. Fixed bug in SiRPAC related to explicit use of ordinals rdf:_1 etc.Added a new example, a tiny utility that generates unique resource identifiers (org.w3c.rdf.examples.CreateUniqueURIs) |
| 2000-09-03 | Download: <rdf-api-2000-09-03.zip> (jarfile only) Bugfix release, 100% contributed by William Grosso. No changes in the API. Fixed bug that prevented source code from being compiled properly Replaced package org.w3c.rdf.implementation.model by more efficient code provided by Bill (from now on, Java 1.2+ is required) Serializer (org.w3c.rdf.implementation.syntax.sirpac.SiRS) now generates correct syntax for class names that contain spaces |
| 2000-05-12 | Download: <rdf-api-2000-05-12.zip> (jarfile only) latest release that worked with Java 1.1.x; newer releases require Java 1.2+ added support for RDF schema: edu.stanford.db.rdf.schema.RDFSchemaModel (includes validation)added support for UML over RDF: edu.stanford.db.rdf.uml.UMLModel (includes validation)generated vocabulary classes forDublinCore,UML Core,StateMachines,DataTypes,Behavior experimental support for order by reification. Methods for ordering are in org.w3c.rdf.util.OrderUtil. (added support for rdf:order and rdf:backwardOrder to SiRPAC)improved SiRS (serializer), uses entities to generate compact syntax (also support for order)minor bugfixes in SiRPACfixed the security bug in the statement digest algorithm (reported by Brian McBride). Model digest is still insecure.added exceptions to the core interfaces (org.w3c.rdf.model.ModelException)added method isEmpty() to model added createOrdinal() to NodeFactory, removed ord() from RDFUtil changed RDFConsumer: addStatement() receives a statement as a parameter instead of (s, p, o)added isMutable() to Model made vocabularies be classes instead of interfaces. A NodeFactory that creates custom resources can now be set using a static method |
| 2000-04-13 | Download: <rdf-api-2000-04-13.zip> (jarfile only) Contains improvements proposed by Stefan Haustein: Reorganized the package structure: org.w3c.rdf.model.impl.ModelConsumer -> org.w3c.rdf.util.ModelConsumer org.w3c.rdf.syntax.xml -> org.w3c.rdf.util.xml org.w3c.rdf.model.impl -> org.w3c.rdf.implementation.model org.w3c.rdf.syntax.* -> org.w3c.rdf.implementation.syntax.* Added NodeFactory interface to org.w3c.rdf.model and updated RDFConsumer. Now the parsers can create custom RDF nodes during parsing. Updated the strawman parser: now it starts interpreting XML as RDF only when it encounteres one of the attributes rdf:instance, rdf:for, or rdf:resource. triples of the kind (X, rdf:type, rdfs:Resource) are filtered out before passing to RDFConsumer |
| 1999-12-18 | Download: <rdf-api-1999-12-18.zip> (jarfile only) SHA-1 algorithm (160-bit hash) is now used by default instead of MD5 (128-bit) to compute the URIs for reified statements, models and anonymous resources. |
| 1999-12-16 | Download: <rdf-api-1999-12-16.zip> (jarfile only) Classes org.w3c.rdf.model.Triple and org.w3c.rdf.model.RDFModelhave been renamed into org.w3c.rdf.model.Statement and org.w3c.rdf.model.Modelrespectively. Strawman parser package added: org.w3c.rdf.syntax.strawman Generic RDF/XML parser package added: org.w3c.rdf.syntax.xml Minor bug fixes |
| 1999-12-06 | Download: <rdf-api-1999-12-06.zip> (jarfile only) Original preview package |
Examples
Some examples are contained in the packageorg.w3c.rdf.examples. Please use them to familiarize yourself with the API. Run
to list the command line parameters of this tool.
Vocabulary class generator
All vocabulary classes (RDF, RDFS, DC etc) included in the distribution were generated using this utility.
Examples:
java edu.stanford.db.rdf.vocabulary.Generator -s http://www.w3.org/1999/02/22-rdf-syntax-ns# -o org.w3c.rdf.vocabulary.rdf_syntax_19990222.RDF
java edu.stanford.db.rdf.vocabulary.Generator -n http://www.w3.org/2000/01/rdf-schema# -s http://www.w3.org/2000/01/rdf-schema -o org.w3c.rdf.vocabulary.rdf_schema_200001.RDFS
java edu.stanford.db.rdf.vocabulary.Generator -s http://www-db.stanford.edu/~melnik/rdf/vocabulary/dublin-core-19990702.rdf -o org.w3c.rdf.vocabulary.dublin_core_19990702.DC -n http://purl.org/dc/elements/1.1/
Creating unique URIs
Sometimes there is a need to generate a unique identifier for a resource that does not inherently have a URI e.g. a person. A list of unique resource identifiers (URIs) can be created as follows:
java org.w3c.rdf.examples.CreateUniqueURIs []
Cryptographic digests of RDF models and statements
The default implementation of the API interfaces supports computing cryptographic digests of models and statements. This approach provides a straightforward way of digital signing of RDF content (as opposed to signing of serialized RDF), facilitating the "Web of Trust". URIs of statements and models are based on their digests.
Standard SHA-1-based cryptographic digests are used in the algorithm. The digest algorithm for a statement with subjects, predicate p and object o is:
d1 = SHA1(s) d2 = SHA1(p) d3 = SHA1(o)
if(o instanceof Literal) rotate left d3 by 8 bits
statement_digest = SHA1( concat(d1, d2, d3) )
The digest algorithm for models (suggested by Steve Dunham) is
model_digest = SHA1( concat( sort( statment_digests )))
The statement digests are introduced to the SHA1 algorithm sorted bytewise in an increasing order. The digests of URIs and literals are computed over UTF-8 encoded strings.