Re: [DotGNU]GNU.RDF

[James Michael DuPont]

Here are some more links to look at :
This is an important project to look into
D2R MAP - Database to RDF Mapping Language and Processor
D2R MAP is a declarative language to describe mappings between
relational database schemata and OWL ontologies. The mappings can be
used by a D2R processor to export data from a relational database to
RDF.
http://www.wiwiss.fu-berlin.de/suhl/bizer/d2rmap/D2Rmap.htm

Here is an overview of RDF Databases and queries
http://www.w3.org/2001/Talks/0505-perl-RDF-lib/

Redfoot is a python application for rdf
http://www.garshol.priv.no/download/xmltools/prod/Redfoot.html
http://redfoot.sourceforge.net/

Here is another older example of a rdf database
http://www.w3.org/1999/02/26-modules/User/RdfSQL-HOWTO.html

Here is an interesting page that describes how Redland can
be used, it also supports a Berkley DB query system
http://www.mindswap.org/~rreck/cawur.shtml

--- James Michael DuPont <address@hidden> wrote:
> 
> --- Peter Minten <address@hidden> wrote:
> > James Michael DuPont wrote:
> > > 
> > > Looks good peter.
> > > There are a couple of things that you might want to think about.
> > > 
> > > Isolation and abstraction.
> > 
> > Could you explain that please?
> 
> It should be possible to isolate the structure of the tables from the
> interface to them. A clean interface will make the layout of the
> tables
> irrelvant. Also we should be able to plug in implementations from
> various RDF database implementations into the framework.
> 
> In fact, I think that we can use alot of the good work done with
> Redland, personally, I find that dave beckett has done a great job,
> it is GPL compatible and industrial strength.
> 
> > > The design of Database Tables are going to have to abstracted a
> > bit.
> > > Maybe you will want to hold values, integers, uris in the tables.
> > 
> > Here's a new attempt:
> > 
> > TABLE triples
> > {
> >     subject: unsigned long; //refers to table strings
> >     predicate: unsigned long; //refers to table strings
> >     object: unsigned long; //refers to a data table
> >     objecttype: char[1]; //tells what is the type of the object
> >     //'s' = string, 'i' = integer
> > }
> > INDEX ON (subject) AND (subject AND predicate);
> > 
> > TABLE strings
> > {
> >     pkey: unsigned long;
> >     value: text;
> > }
> > 
> > 
> > Note that if object type is 'i' I use a little trick to improve
> > efficiency: the
> > first 32 bits of object are taken and placed into a signed integer
> > using a
> > simple bit copy. If I would place integers in a separate table that
> > wouldn't
> > make much sense since I would require 2 unsigned longs as foreign
> > key/primary
> > key while the actual value is only an integer.
> > 
> > Also note that this model can be expanded for other data types. But
> > this is the
> > general setup.
> 
> OK, well yes and no.
> 
> First of all, you need three indexes: 
> 1. Subject and Predicate
> 2. Object and Predicate
> 3. Subject and Object
> 
> Second of all, I think you may want to use URIS as the primary keys
> and
> avoid making the numeric ids. The database should be able to deal
> with
> long keys, and that will make your database model simpler.
> 
> It should be possible to use a database model where each type of
> subject has its own table. I want to look at the current research on
> the RDFDBS before commenting further :
> 
> http://www-db.stanford.edu/~melnik/rdf/db.html
> Storing RDF in a relational database
> This page summarizes some current approaches to storing RDF in a
> relational database. THIS IS A REQUEST FOR COMMENTS, so please do
> contribute your ideas (address@hidden)! To goal is to come
> up
> with the best way of storing RDF in a relational database, or
> identify
> a set of solutions that are suitable for particular needs. 
> Motivation
> 
> http://www.guha.com/rdfdb/
> What is rdfDB
> rdfDB is intended to be a simple, scalable, open-source database for
> RDF for systems like Semantic Web Services. 
> The goals of this project are to build a database that is capable of 
> 
> * Supporting a graph oriented API via a textual query language ala
> SQL.
> 
> * Load/Reload an RDF file from a url into the database 
> * Scalable to millions of nodes and triples. 
> * Provide support for RDF Schemas. 
> * Provide support for some basic forms of inferencing. 
> * Provide both C and Perl access to the database. 
> * The Perl philosophy applies : Simple things should be simple and
> complex things should be possible. 
> 
> http://www.w3.org/2001/sw/Europe/reports/rdf_scalable_storage_report/
> SWAD-Europe: Scalability and Storage: Survey of Free Software / Open
> Source RDF storage systems 
> Objectives
> * Demonstrate storage of large-scale dynamic Semantic Web data 
> * Develop storage system with optimised support for querying Semantic
> Web data, schemas and provenance 
> * Report on implementation issues for storing Semantic Web data 
> 
> http://ilrt.org/discovery/2001/02/imeshdb/
> IMesh DB: A Model and Implementation of Information Discovery for the
> IMesh Toolkit 
> Author: Libby Miller 
> Abstract
> This paper is about modelling, storing and querying complex metadata
> about people and organisations. It describes the use of an ABC-like
> metadata model to represent contextual information about the
> discovery
> and creation of metadata. It also describes the use of the Squish
> query
> language and Java implementation to store and query this metadata in
> RDF. 
> 
> http://ilrt.org/discovery/2000/10/swsql/
> Overview
> This is a quick writeup some work in progress, exploring various
> inter-relationships between relational databases, tools from the
> logic
> programming community, and W3C's RDF. We first discuss some broad
> issues surrounding RDF APIs and query systems, before exploring a
> number of more detailed case studies. Our first case study is based
> around our SQL-ish ("Squish") interface to any RDF database that
> exports either the Jena or Stanford RDF APIs. Our second case study
> shows how tools from the logic programming community can be used to
> export RDBMS systems to the Web. 
> 
> 
> http://www.ktweb.org/article3-tab.cfm
> Here is a good overview of Ont. Editors (I need to reviw this more)
> 
> > 
> > > I would like to try and help out on this.
> > 
> > Great. What do you think of my new model?
> 
> I think I need to do more research and cite some of the existing
> programs, and see what I can learn from thier mistakes. Then I can
> comment more.
> 
> please keep up the good ideas,
> mike
> 
> 
> =====
> James Michael DuPont
> http://introspector.sourceforge.net/
> 
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=====
James Michael DuPont
http://introspector.sourceforge.net/

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