Thanks Ashok , Yes, I am talking about relational databases.
It would be nice to understand if the issue is already covered and to
which extend.

Thanks again.

On Thu, Nov 12, 2009 at 4:51 PM, ashok malhotra
<> wrote:
> Hello Angela:
> Just to be clear, you are speaking about multiple relational databases,
> right?
> If so, several existing tools solve that problem.  I will let the owners of
> the tools
> speak for themselves.
> If you are talking about a mixture of relational and non-relational
> databases, then that
> is a more difficult problem.  I don't think our work on the WG will address
> that.
> All the best, Ashok
> Fogarolli Angela wrote:
>> Hi all,
>> I am new to the group so I don't know if I understood correctly the
>> previous work done by the group and the objectives. I would like to
>> ask some questions for clarifying a couple of points related to the
>> issue came up during the last conference call which is about the
>> Mapping Language we should deliver.
>> I apologize if I am misunderstood or if this is not focused on the
>> objectives of the group.
>> I am currently leading a data integration project at the instance
>> level using the OKKAM infrastructure. We were thinking to use D2R for
>> avoiding the implementation of a big KB.
>> A big issue I see also in this experience is the necessity to run
>> queries on multiple data sources.
>> From the project presentations we listened to till now it emerged that
>> we are able to map databases to RDF but we are not able to connect
>> them so we are not able to run queries which span multiple databases
>> (please, tell me if I am wrong...I am not an expert, just trying to
>> clarify to myself some ideas in order to be helpful in the future).
>> I was thinking that since it's possible to decompose queries using
>> relational algebra and this mapping should be an objective of this
>> group (?) then the same mapping could be used to understand to which
>> database (or sparql endpoint) to send a piece of query.
>> I am not sure that this problem is part of the objectives of this
>> group, even though I think that the data integration issue should be
>> addressed, as written in the W3C RDB2RDF Incubator Group Report
>>  (point 1.1.3
>> Integration of Enterprise Information Systems)
>> My question is:
>> Could the mapping delivered by this group also solve (or provide a way
>> to solve) the problem of the sparql federated queries ? I think this
>> will be extremely important for implemented the linked data idea.
>> In my point of view once we have created a mapping from sparql to sql
>> then this can also be re-used for implemented federated queries.
>> Thanks in advance.
>> Angela
>> On Thu, Nov 12, 2009 at 2:33 PM, ashok malhotra
>> <> wrote:
>>> Hello Ahmed:
>>> I envision that the work of the WG is one-way: from RDB to RDF/OWL.
>>> So, to answer your question, I do not envision creating SQL tables in the
>>> RDBMS from SPARQL application using R2RML.
>>> All the best, Ashok
>>> Ezzat, Ahmed wrote:
>>>> Hi Ashok,
>>>> Thanks for the follow up. I agree with your clarification regarding the
>>>> mapping SPARQL to SQL is out of scope; having discussion about it if the
>>>> team want to pursue is fine - I am trying to separate what we discuss,
>>>> with
>>>> time constraints, from what we will commit to deliver which we need to
>>>> pin
>>>> down early 2010.
>>>> I liked the D2R presentation scope in the mapping area; is reasonable.
>>>> Regarding DDL statements mapping support: do you envision creating SQL
>>>> tables in the RDBMS from SPARQL application using R2RML or do you
>>>> envision
>>>> the ability through the R2RML to read the different schema objects
>>>> definitions in the RDBMS from a SPARQL application?  I agree that the
>>>> latter
>>>> is a must and would be interested in getting your input as well as
>>>> others on
>>>> the first.
>>>> Regards,
>>>> Ahmed
>>>> -----Original Message-----
>>>> From:
>>>> [] On Behalf Of ashok malhotra
>>>> Sent: Wednesday, November 11, 2009 13:58
>>>> To: RDB2RDF WG
>>>> Subject: ISSUE-3
>>>> Since the goal of the WG is to create a mapping from RDB Schemas to
>>>> RDF/OWL classes, perhaps
>>>> we should rephrase the bullet point in the requirements as
>>>>   * The mapping language MUST define the set of SQL DDL
>>>>     to be supported in the first release. The set to be supported
>>>>     SHOULD be as complete as possible and be defined as soon as
>>>>     possible after the WG official launch.
>>>> This will let us exclude Table Types if we wish.
>>>> I apologize that the original bullet was interpreted to mean that the
>>>> the
>>>> WG should define
>>>> a mapping from SPARQL to SQL.  That was not the intention.  In my view,
>>>> the mapping of
>>>> SPARQL to SQL should be left open as a technology on which various
>>>> implementations
>>>> can compete. .

Received on Thursday, 12 November 2009 16:30:34 UTC