Re: ISSUE-3

Juan,

> Given your email, do we have a volunteer to come up with initial list of DDL
> stmts to be supported?

While we're here: I've created a Wiki page for it now [1] - want to take
over? :)

Cheers,
      Michael

[1] http://www.w3.org/2001/sw/rdb2rdf/wiki/Requirements/DDLCoverage

-- 
Dr. Michael Hausenblas
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730
http://linkeddata.deri.ie/
http://sw-app.org/about.html



> From: "Ezzat, Ahmed" <Ahmed.Ezzat@hp.com>
> Date: Mon, 16 Nov 2009 20:07:57 +0000
> To: Juan Sequeda <juanfederico@gmail.com>
> Cc: Harry Halpin <hhalpin@w3.org>, RDB2RDF WG <public-rdb2rdf-wg@w3.org>
> Subject: RE: ISSUE-3
> Resent-From: RDB2RDF WG <public-rdb2rdf-wg@w3.org>
> Resent-Date: Mon, 16 Nov 2009 20:09:28 +0000
> 
> 
> Clearly we need to make a list; I do not expect issues.  I expect the
> discussions to take more time along which standard (SQL92, SQL98, 2003, etc),
> and supporting vendor specific data types.
> 
> As I stated earlier, the final version to reflect what we will deliver will
> come out from the discussions and that will take few weeks/months (I am
> guessing and shooting to be done before March 2010).
> 
> Given your email, do we have a volunteer to come up with initial list of DDL
> stmts to be supported?
> Regards,
> 
> Ahmed
> 
> 
> Ahmed K. Ezzat, Ph.D.
> HP Fellow, Business Intelligence Software Division
> Hewlett-Packard Corporation
> 11000 Wolf Road, Bldg 42 Upper, MS 4502, Cupertino, CA 95014-0691
> Office:      Email: Ahmed.Ezzat@hp.com<mailto:Ahmed.Ezzat@hp.com> Off:
> 408-447-6380  Fax: 1408796-5427  Cell: 408-504-2603
> Personal: Email: AhmedEzzat@aol.com<mailto:AhmedEzzat@aol.com> Tel:
> 408-253-5062  Fax:  408-253-6271
> 
> ________________________________
> From: Juan Sequeda [mailto:juanfederico@gmail.com]
> Sent: Monday, November 16, 2009 12:01 PM
> To: Ezzat, Ahmed
> Cc: hhalpin@w3.org; RDB2RDF WG
> Subject: Re: ISSUE-3
> 
> Does that mean that besides the ddl statements to create objects, everything
> else in the DDL is in? Or is there something else in the DDL that should not
> be considered?
> 
> Shouldn't we actually make a list of all the statements that are in (create
> table, foreign key/references, primary key, unique, not null, null, etc)
> 
> Juan Sequeda, Ph.D Student
> Dept. of Computer Sciences
> The University of Texas at Austin
> www.juansequeda.com<http://www.juansequeda.com>
> www.semanticwebaustin.org<http://www.semanticwebaustin.org>
> 
> On Mon, Nov 16, 2009 at 2:45 PM, Ezzat, Ahmed
> <Ahmed.Ezzat@hp.com<mailto:Ahmed.Ezzat@hp.com>> wrote:
> 
> 
> In other words: DML statements are out.  DDL statements that create objects
> are also out.  DDL statements like Describe are needed for tools to map the
> RDBMS schema into RDFS or OWL.  I think that should be relatively simple, the
> main challenge which we need to pin down is which data types to support
> mapping to, if we are or are not going to provide support to vendor specific
> SQL data types.  This would be a good milestone...
> 
> Let us finalize that then we will reflect that into a document the WG will
> commit to deliver.
> 
> Ahmed
> 
> -----Original Message-----
> From: 
> public-rdb2rdf-wg-request@w3.org<mailto:public-rdb2rdf-wg-request@w3.org>
> [mailto:public-rdb2rdf-wg-request@w3.org<mailto:public-rdb2rdf-wg-request@w3.o
> rg>] On Behalf Of Ezzat, Ahmed
> Sent: Monday, November 16, 2009 11:17 AM
> To: hhalpin@w3.org<mailto:hhalpin@w3.org>
> Cc: RDB2RDF WG
> Subject: RE: ISSUE-3
> 
> Harry,
> 
> It is not clear to me which DDL statement you want to support or have in mind,
> can you give me some example?
> 
> Ahmed
> 
> 
> 
> -----Original Message-----
> From: hhalpin@w3.org<mailto:hhalpin@w3.org>
> [mailto:hhalpin@w3.org<mailto:hhalpin@w3.org>]
> Sent: Monday, November 16, 2009 11:05 AM
> To: Ezzat, Ahmed
> Cc: RDB2RDF WG
> Subject: RE: ISSUE-3
> 
> On Mon, 16 Nov 2009, Ezzat, Ahmed wrote:
> 
>> 
>> 
>> Agree.  It also seems there is consensus from the email exchange and talking
>> with Ashok that the 2nd MUST in your list from the charter: "The mapping
>> language MUST define the set of relational algebra to be supported in the
>> first release." will be eliminated.
>> 
> 
> Yes, I agree that the second MUST seems to indicate that there will be a
> mapping, at least on the semantic level, between SPARQL and SQL.
> 
>  However, I suspect that the main reason that's in the charter is just
> that the WG be clear exactly what part of the DDL and DML will be
> supported or not, and to make this decision as early as possible (which
> is why having this debate now is a good thing).
> 
> I would be happy to rephrase it as per Ashok's rephrasing [1] and ask the
> W3C if the charter can be changed in this manner. However, that particular
> requirement is written such that we simply have to declare which subset we
> want to support, which can be simply be the DDL. That would satisfy the
> MUST of the requirement. However, if someone has a dissenting opinion, now
> would be a good time to send it to the list-serv.
> 
> [1] http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2009Nov/0018.html
> 
> 
> 
>> 
>> Once we talk more in the next few months and try to pin down the data types
>> to be supported (MUST) and a mechanism to support vendor specific data types
>> (as time allow), we will be in a good shape.
>> 
>> At that time, we will have a concrete document that reflect what we will
>> commit to.
>> Regards,
>> 
>> Ahmed
>> 
>> Ahmed K. Ezzat, Ph.D.
>> HP Fellow, Business Intelligence Software Division
>> Hewlett-Packard Corporation
>> 11000 Wolf Road, Bldg 42 Upper, MS 4502, Cupertino, CA 95014-0691
>> Office:      Email:
>> Ahmed.Ezzat@hp.com<mailto:Ahmed.Ezzat@hp.com><mailto:Ahmed.Ezzat@hp.com<mailt
>> o:Ahmed.Ezzat@hp.com>> Off: 408-447-6380  Fax: 1408796-5427
>> Personal: Email:
>> AhmedEzzat@aol.com<mailto:AhmedEzzat@aol.com><mailto:AhmedEzzat@aol.com<mailt
>> o:AhmedEzzat@aol.com>> Tel: 408-253-5062  Fax:  408-253-6271
>> 
>> 
>> -----Original Message-----
>> From: hhalpin@w3.org<mailto:hhalpin@w3.org>
>> [mailto:hhalpin@w3.org<mailto:hhalpin@w3.org>]
>> Sent: Monday, November 16, 2009 10:23 AM
>> To: Ezzat, Ahmed
>> Cc: Richard Cyganiak;
>> ashok.malhotra@oracle.com<mailto:ashok.malhotra@oracle.com>; RDB2RDF WG
>> Subject: RE: ISSUE-3
>> 
>> On Thu, 12 Nov 2009, Ezzat, Ahmed wrote:
>> 
>>> 
>>> 
>>> The current charter has some ambiguity and the purpose of this discussion is
>>> to come up with a more precise statement that reflects what the team thinks
>>> but also taking into consideration time constraints.
>> 
>> Note that the charter does specify only the following as MUST [1]:
>> 
>> "The mapping language MUST define the mapping of relational data and
>> relational schemas to RDF and OWL"
>> 
>> "The mapping language MUST define the set of relational algebra to be
>> supported in the first release."
>> 
>> "The mapping language MUST allow for a mechanism to create identifiers for
>> database entities"
>> 
>> What we need to clarify is exactly the nature of the first must, but I
>> concur with Ahmed and the general consensus that we should be "read" only
>> and that mapping should be done so that it allows a database to be directly
>> exported into RDF, not in response to a specific mapping of a
>> particular SPARQL query into SQL. One can imagine how work in doing so
>> could be built from the work of a general semantic mapping from relational
>> data to RDF that the syntax of R2RML will embody, but this is not within
>> the scope of the R2RML syntax.
>> 
>> With particular issues such as "The mapping language SHOULD be able to
>> support vendor specific SQL data types", this is precisely what needs to
>> be hashed out in the WG. It seems there should be some kind of general
>> extensibility mechanism for vendor-specific data-types and functions. I
>> would like to see links to such work if it exists.
>> 
>> [1] http://www.w3.org/2009/08/rdb2rdf-charter.html
>> 
>>> 
>>> The first issue was to clarify that mapping SPARQL to SQL is not part of
>>> what we are talking about, i.e., removing relational algebra mapping from
>>> the charter.  From the dialogue we are having I am reading that the answer
>>> is NO to SPARQL/SQL mapping.
>>> 
>>> Now, the language is limited to mapping data types and there is desire and
>>> interest to explore a means to support vendor specific data types; this
>>> would be desirable.
>>> 
>>> As an example, in traditional, 30-years old RPC, you define structure
>>> (object) in an IDL file and the stub compiler generates the functions that
>>> marshal / un-marshal this structures, and also generate stub and skeleton
>>> routines which in turn calls these marshal/un-marshal functions.  Good RPC
>>> stub compilers would allow you as a user to define the
>>> marshalling/un-marshalling functions for a given structure/object your self,
>>> but the compiler provides the framework to support integrating your
>>> marshalling/un-marshalling functions with the generated stub/skeleton
>>> routines.  This is meant as an example to possibly address supporting vendor
>>> specific data types.
>>> 
>>> It is the purpose of this initial period, few months after the presentations
>>> are complete, to pin down what is included and what is not.   In other
>>> words, it is the goal of this group to answer the scope of your suggestions
>>> below about XML data type, etc.
>>> 
>>> Ahmed
>>> 
>>> -----Original Message-----
>>> From: Richard Cyganiak
>>> [mailto:richard.cyganiak@deri.org<mailto:richard.cyganiak@deri.org>]
>>> Sent: Thursday, November 12, 2009 2:23 PM
>>> To: Ezzat, Ahmed
>>> Cc: ashok.malhotra@oracle.com<mailto:ashok.malhotra@oracle.com>; RDB2RDF WG
>>> Subject: Re: ISSUE-3
>>> 
>>> On 12 Nov 2009, at 16:26, Ezzat, Ahmed wrote:
>>>> Given that the goal of the WG is to create a mapping from RDB
>>>> Schemas to RDF/OWL classes only.  This require us to be able to read
>>>> the schema but not necessarily to modify it.
>>> 
>>> +1 for scoping this WG to read-only access.
>>> 
>>>> This leads me: R2RML mapping language MUST support as complete as
>>>> possible all SQL data and object types and any exceptions will be
>>>> identified as soon as possible after the WG launch.
>>> 
>>> +1 for supporting as many SQL data types as possible. But what's the
>>> target for "all" data types? Does this include, say, the XML type of
>>> SQL:2003? What about types that are not in the standard but commonly
>>> used in popular RDBMS? I don't even know if SQL:2008 adds any new
>>> datatypes...
>>> 
>>> Are you saying that user-defined object types should be supported in
>>> the language? I'm opposed to that idea. My impression is that this is
>>> implemented very inconsistently across different RDBMS, if at all; it
>>> adds a lot of complexity to the already big overall task of the WG;
>>> I'm not aware of any existing RDB2RDF system that handles them from
>>> which we could learn, so we move from standardisation into research
>>> territory; I would have no idea how methods with arguments should be
>>> handled; and only a small minority of RDBMS users seem to be using
>>> user-defined object types. So from my POV the case for including them
>>> is weak; certainly not good enough for a MUST at this stage.
>>> 
>>> Best,
>>> Richard
>>> 
>>> 
>>>> 
>>>> All, does the above capture what the goal is.
>>>> Feel free to edit/agree/disagree, etc..
>>>> Regards,
>>>> 
>>>> Ahmed
>>>> 
>>>> 
>>>> -----Original Message-----
>>>> From: ashok malhotra
>>>> [mailto:ashok.malhotra@oracle.com<mailto:ashok.malhotra@oracle.com>]
>>>> Sent: Thursday, November 12, 2009 05:34
>>>> To: Ezzat, Ahmed
>>>> Cc: RDB2RDF WG
>>>> Subject: Re: ISSUE-3
>>>> 
>>>> 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: 
>>>>> public-rdb2rdf-wg-request@w3.org<mailto:public-rdb2rdf-wg-request@w3.org>
>>>>> [mailto:public-rdb2rdf-wg-request@w3.org<mailto:public-rdb2rdf-wg-request@
>>>>> w3.org>
>>>>> ] 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 Tuesday, 17 November 2009 16:53:05 UTC