Some proposed RDF APIs. GINF: http://www-db.stanford.edu/~melnik/rdf/api.html, RADIX: http://www.mailbase.ac.uk/lists/rdf-dev/1999-06/0002.html, Netscape Communicator: http://lxr.mozilla.org/seamonkey/source/rdf/base/idl/, RDF for Java: http://www.alphaworks.ibm.com/formula/rdfxml/.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....the Open Directory Portal of Netscape comprises around 100M of Subject Topics and 700M of indexed URIs) It becomes evidentthatbrowsing suchlargede scription bases is a quite cumbersome and time consuming task. Unfortunately, this is the only support provided by existing RDF enabled systems [46] relying on low level APIs and file based implementations. The question that naturally arises is to what extent can DBMS technology be used to support declarative access and secondary storage management for RDF description bases. Clearly, standard (relational or object) databases [4] are too rigid ....

.... Table 1 for formal definitions) can be used to generate such Portal interfaces, either off line (i.e. by materializing the various query results in HTML XML files) or online (by computing query answers on the fly) Up to now this access functionality is supported by existing RDF enabled systems [46] using low level APIs and file based implementations. Towarmup readers, we start with queries which can find all the schema classes or properties used in a Portal Catalog: Class and Property hold all the labels of nodes and edges that can be used in an RDF description base. In our example, these ....

Some proposed RDF APIs. GINF: http://www-db.stanford.edu/~melnik/rdf/api.html, RADIX: http://www.mailbase.ac.uk/lists/rdf-dev/1999-06/0002.html, Netscape Communicator: http://lxr.mozilla.org/seamonkey/source/rdf/base/idl/, RDF for Java: http://www.alphaworks.ibm.com/formula/rdfxml/. 25

....fail to fully accommodate RDFS 1 www.w3.org Metadata 2 www.dmoz.org, home.cnet.com, www.xmlnews.org features such as specialization of properties. Furthermore, they have been designed for data that are more strongly typed than RDF resource descriptions. Finally, existing RDF enabled systems [19]and logical languages (SiLRI [9] Metalog [16] suffer from a number of defficiencies: a) RDF schemas are either ignored or substituted by other formalisms (e.g. F Logic)# (b) RDF containers (e.g. bags, sequences) are not captured# (c) they do not consistently support complex querying on data ....

Some proposed RDF APIs. GINF: http://www-db.stanford.edu/~melnik/rdf/api.html, RADIX: http://www.mailbase.ac.uk/lists/rdf-dev/1999-06/0002.html, Netscape Communicator: http://lxr.mozilla.org/seamonkey/source/rdf/base/idl/, RDF for Java: http://www.alphaworks.ibm.com/formula/rdfxml/.

....data. In fact, many information providers (e.g. ABC News, CNN and Time Inc. and Web portals (e.g. Open Directory) already support RDF. Moreover, to interpret metadata across several communities, RDF allows the definition of schema vocabularies [10] Unfortunately, existing RDF enabled systems [32] totally ignore RDF schemas during metadata manipulation: at best, browsing and querying is limited to attribute value pairs. In this paper, we propose a declarative query language (OQL like [12] called RQL, in order to query both RDF descriptions and related schemas as (semistructured) graph ....

....by the previously presented semistructured systems. 6 Conclusions and Future Work We believe that declarative query languages for metadata like RQL, open new perspectives for effective and efficient metadata management. Indeed, RQL can be used as a high level language (opposed to existing APIs [32]) to access various RDF metadata repositories, either as a stand alone application or as part of a distributed middleware architecture. In both cases, the ability of RQL to transparently exploit taxonomies of classes and property types is crucial in order to query RDF (meta)data with partial or no ....

Some proposed RDF APIs. GINF: http://www-db.stanford.edu/~melnik/rdf/api.html, RADIX: http://www.mailbase.ac.uk/lists/rdf-dev/1999-06/0002.html, Netscape Communicator: http://lxr.mozilla.org/seamonkey/source/rdf/base/idl/, RDF for Java: http://www.alphaworks.ibm.com/formula/rdfxml/.

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