Dev Day www2003 - RDQL for REAL !
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Demonstration by @semantics - a young company - that is going to make  
the Semantic Web a Reality. What will be presented are the results of  
some of our first contracts: two real live RDQL applications, by means  
of a demo, a short overview of their business case followed by the  
actual RDQL query and system architecture.

Case Study I: Image ShowCase
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Image ShowCase (ISC) is a project developed for the European Space  
Agency ESA/ESRIN [1]. The Agency publishes examples of satellite images  
acquired by different sensors of the ENVISAT satellite, ERS 2 satellite  
and other satellites. These images are used as examples to explain and  
promote the use of Earth Observation techniques. The main objective of  
the project is to simplify and unify access to the Image Showcases for  
generic public, in the "6-66 years range". This is intended to be a  
free service open to everybody. The objective is to avoid all the  
complex interfaces, remote sensing jargon, various specialist map  
interfaces, exclude java applets or browser plug-ins and simplify the  
interface to make it compatible with all browsers. What we build is a  
Google like interface which gives one/two clicks access to the data  
using RDF and RDQL [2] with maps or free text words. In addition to  
these "Google" functions we added more complex navigation functions eg,  
to show all images related to one case and to follow links to other  
available "see also" information.

The approach adopted starts from parsing of the original, hand-written  
data, and creating RDF descriptions. RDF descriptors are collected  
regularly from all sites where resources reside. This has been done by  
a simple RDF gathering mechanism. After gathering, all descriptors are  
ingested in RDFStore [3]. Perl DBI is used to query all descriptors  
using RDQL language [2].


Case Study II: Last Minute News
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A variety of news clipping services are operating today. These range  
from services of Moreover, NewsIsFree, Google News and others. Last  
Minute News (LMN) is a prototype system of a “real-time” news clipping  
service. LMN is intended mainly as technology demonstrator and as a  
mock-up for testing dynamic aspects of RDF ingestion and indexing and  
RDQL [2] querying. The objective is to offer narrow search functions  
for fresh daily news and related images trying to reduce  
false-positives by considering additional information about sources.

The news sources are harvested at regular intervals and parsed to  
create RSS1.0 compliant RDF descriptions of the contents available.  
Parsing is done on different sources, which, not surprisingly, show  
similar structure. Parsing extracts description, date, date of  
acquisition, author (when available), title and all images related to  
the article. In some cases, news articles offer a “see also” section  
with related articles. Once parsed from the news sources, RDF data are  
ingested in RDFStore [3]. A simple RDF gathering protocol is used in  
this case as the RDF creation is done, after harvesting, at one single  
place.

Conclusion:
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The sections will conclude with the actual RDQL queries used; an  
explanation of what they do and what is missing there, as well as an  
overview of the system architecture.

RDQL works ! It allows cost effective application design and  
implementation; it is easy to use and developers get into it quickly;  
it can deal with real-world data which is messy and not homogeneous. It  
allows deployment without changing the workflow or people their habits.  
Of course, this is just the first step toward the Semantic Web.


[1] European Space Agency  ESRIN, Frascat, http://www.esrin.esa.it/
[2] L Miller, A Seaborne, A Reggiori - "Three Implementations of  
SquishQL, a Simple RDF Query Language" -  
http://www-uk.hpl.hp.com/people/afs/Papers/ISWC%202002%20- 
%20SquishQL.htm
[3] RDFStore - http://rdfstore.sourceforge.net