Re: please read before participating in translation scheme debate [Re: Translating DB values to RDF terms using 1) R2RML views and 2) using R2RML-native translation scheme]

Kingsley, 


I agree fully with you about the power of views. In fact that was the point I was trying to emphasize. Such views, besides regular tables, are indeed the targets of R2RML. Use of views (or more specifically, queries or view definitions) are sufficient to specify unrestricted translation as illustrated in Examples 1 and 2 in http://www.w3.org/2001/sw/rdb2rdf/wiki/Translating_Database_Values_to_RDF_Terms 


Note that the main reason we have introduced constructs in R2RML for specifying "R2RML views" (sql query string), instead of relying solely on traditional DB views, is to allow mapping avoiding any privilege issues regarding DB view creation in the host database (e.g., if the host database is Read-Only). 


Thanks, 
- Souri. 

----- Original Message ----- 
From: kidehen@openlinksw.com 
To: public-rdb2rdf-wg@w3.org 
Sent: Wednesday, December 14, 2011 5:43:51 PM GMT -05:00 US/Canada Eastern 
Subject: Re: please read before participating in translation scheme debate [Re: Translating DB values to RDF terms using 1) R2RML views and 2) using R2RML-native translation scheme] 


On 12/14/11 4:44 PM, Souripriya Das wrote: 




Has anybody else looked at the "R2RML view" based translation scheme and examples in 
http://www.w3.org/2001/sw/rdb2rdf/wiki/Translating_Database_Values_to_RDF_Terms 



If not, please do. I'd very interested in what you think about use of just R2RML views for specifying translation info. 
The power of "R2RML views" may be sufficient in practice. 


Thanks, 
- Souri. 

Souri, 

Can't that same SQL statement be used to create normal SQL View that's simply treated like a Table re. R2RML mapping? We support those constructs in SQL and that's exactly what we recommend to our users i.e., use the RDBMS engines SQL sophistication to create Views that are then treated like Tables when it comes to the RDF Views mappings. The same even applies to Stored Procedures which can also be treated as Views. 

Our own native RDF Views language offers exactly the same thing using different syntax. Thus, for compatibility sake re., interchange of R2RML documents, it's best to localize DBMS specific functionality thereby making conventional SQL Views (transient of materialized) or Tables the targets of R2RML mappings. 

Fundamentally, there's no reason why we shouldn't be able to exchange an R2RML map with you and vice versa. Ditto anyone else that supports R2RML. Simple scenario: 

1. I attach Oracle to Virtuoso via and ODBC or JDBC data source name (DSN) 
2. I generate a native RDF View based on the attached table 
3. I export the RDF Views definitions via an R2RML mapping doc 
4. Publish to a URL 
5. You HTTP GET the resource at the aforementioned URL 
6. Run it through your R2RML processor. 
7. We end up with Resource URIs in different Data Spaces that expose the same data. 

1-7 is my basic acid test for R2ML when implementations become official. 

-- 

Regards,

Kingsley Idehen       
Founder & CEO 
OpenLink Software     
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