Update on Intro to the Use Case

Note: this should be on the wiki, but Dan doesn't have write access to the
wiki, yet


Introduction



In addition to the chartered requirements set out for the R2RML
language [*RDB2RDF,
Working Group Charter, Requirements, **
http://www.w3.org/2009/08/rdb2rdf-charter.html#scope*<http://www.w3.org/2009/08/rdb2rdf-charter.html#scope>
*], *have identified a number of real world scenarios and specific
application requirements. We provide a taxonomy of the application specific
requirements and a set of use cases that provide coverage over the feature
set.  Use cases span those derived from real-world scenarios, hypothetical
scenarios, and small examples intended to illustrate specific issues.



Application Specific Requirements



Integrating relational database content with the Semantic Web is not a
stand-alone process, but a process of integrating that content with other
content from the Semantic Web.  For simplicity we abstract and enumerate
such integration pair wise, where the first web site is a web site
containing relational data to be mapped and the second web site may be any

(please vote)

   1. Semantic Web site
      2. Source of RDF or OWL



Actual applications may have traditional names.  For example, ETL-based
datawarehouse data federation and web-site mashup. In the abstract we
distinguish three refinements of mapping relationally stored data to RDF.

   1. Structured

Consider only highly structured database content, and treat string/text
fields as atomic data types of secondary interest.

   1. Structured + Semistructured

Text fields in the database are elemental.

   1. Structured + Microparsed Tagged Text

Text fields in the database are parsed and tagged per an existing ontology.



Each of these may be combined with a Semantic Web site of one of the above
forms, arbitrary RDF/OWL, that combination may comprised data integration or
mash-up, where mash-up means there are no joins. (predicates on data from 2
or more sources).



Different applications have different roles for an ontology.  These range
from none.  That is table and column names and other parts of SQL-DDL are
exploited as parts of RDF triples and combined with the underliying data.
In such cases an RDFS or OWL file may be synthesized from the SQL DDL.  The
resulting file is called the putative ontology.



An application may require the relational content be mapped to an existing
domain ontology.  Thus, an existing ontology serves as the basis of
federation.  Some applications, in the fashion of datawarehouses, require
that an ontology be created specific to the goal of federating several
existing databases, in the classic mediator-based architecture [cite?]



   1. Expressivity
      1. Node Label Generation

Graph node names are synthesized from a function of database attributes

   1. Datatype expression
         1. Simple
         2. Relational data (cells) are mapped to rdf datatypes per SQL XSD
         mapping.
         3. Micorparsing

Relational data are parsed and mapped to rdf graphs.


Juan Sequeda
+1-575-SEQ-UEDA
www.juansequeda.com