W3C home > Mailing lists > Public > semantic-web@w3.org > June 2009

Re: Owning URIs (Was: Yet Another LOD cloud browser)

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Tue, 02 Jun 2009 11:44:50 -0400
Message-ID: <4A2548F2.6060605@openlinksw.com>
To: Samur Araujo <samuraraujo@gmail.com>
CC: Sherman Monroe <sdmonroe@gmail.com>, Daniel Schwabe <dschwabe@inf.puc-rio.br>, Linked Data community <public-lod@w3.org>, semantic-web@w3.org
Samur Araujo wrote:
> Dear Sherman, note that no matter what query tool or browser you are 
> using, it is necessary to tune the underline database to achieve your 
> performance requirements. Enabling all Explorator's repositories mean 
> that you want to query several databases and sparql enpoint at the 
> same time. When you do so, Explorator queries a federation of 
> endpoints, groups all results and retrieves an  unique set of triples. 
> Of course, you should keep in mind that we have not tune our sesame or 
> virtuoso instances to achieve the best performance, also we have not 
> created FTS for sesame or virtuoso yet.  Again, such performance 
> problem will be encountered no matter what system you use.
> About sesame, we are using it just as a proof of concept, however you 
> can extend Explorator adapters to connect to others rdf repositories. 
> At the moment, Explorator is able to connect to whatever sparql 
> endpoint (we have tested it for Virtuoso and Sesame endpoints.) you 
> want. Keep in mind that we can not guarantee performance for external 
> endpoints. Most of them retrieve timeout when you do a complex query 
> that takes longer that a few milleseconds.

Are you exploiting the "Retry" feature of Virtuoso's Anytime Query function?

Look at: http://lod.openlinksw.com/sparql (note the options at the 
bottom of the page which are part of our sparql protocol extensions).

You have to think in terms of location aware cost-optimization if you 
want to venture into the federated query realm (SPARQL or SQL). We've 
done this work long time ago re. SQL (the Virtual DBMS aspect of 
Virtuoso), and similar work will be delivered re. SPARQL in due course 
(the SPARQL-BI extentions and the Anytime Query functionality are  
critical infrastructure components for this endeavor).

> Regards,
> Samur Araujo
> On Tue, Jun 2, 2009 at 11:45 AM, Samur Araujo <samuraraujo@gmail.com 
> <mailto:samuraraujo@gmail.com>> wrote:
>     Dear Sherman, Notes that doesn
>     On Tue, Jun 2, 2009 at 11:43 AM, Sherman Monroe
>     <sdmonroe@gmail.com <mailto:sdmonroe@gmail.com>> wrote:
>         Daniel,
>         I see some interesting concepts worth exploring here, e.g.
>         using windows (with paging inside the window). But as I refine
>         my query, there isn't any apparent context that orients me in
>         the data. E.g. how does one box/set relate to the others.
>         I notice you're using Sesame, do you think it can scale? I
>         tried selecting several repositories at once, but the system
>         seems to hang awhile (couple of minutes)  before returning
>         results.
>         -sherman
>         On Tue, Jun 2, 2009 at 8:26 AM, Daniel Schwabe
>         <dschwabe@inf.puc-rio.br <mailto:dschwabe@inf.puc-rio.br>> wrote:
>             Kingsley Idehen wrote:
>                 Daniel Schwabe wrote:
>                     Sherman,
>                     as another alternative, I urge you to take a look
>                     at Explorator [1] (there is a short movie
>                     explaining the basic idea, you can also play with
>                     the live interface), which can do all of what you
>                     said, and more.
>                     It provides a more general exploration paradigm,
>                     of which the example you give below is only one of
>                     the possibilities...
>                     Best
>                     Daniel
>                     [1] http://www.tecweb.inf.puc-rio.br/explorator.
>                 Daniel,
>                 When you speak to the <http://lod.openlinksw.com>
>                 instance, do you use SPARQL Protocol or the Faceted
>                 Browsing REST API or either depending on task ?
>                 I suspect SPARQL protocol,  but please confirm.
>             We use the SPARQL protocol, because the code is geared to
>             deal with any SPARQL endpoint. The only thing we have
>             customize, precisely because of lack of standardization,
>             is the FTS function. There is special code to detect when
>             the server is Virtuoso, to use bif:contains. Other than
>             that, is uses standard constructs.
>             If I understand it correctly, the Faceted Browsing REST
>             API would not allow us to issue the kinds of queries we
>             need; as I mentioned in earlier messages, Explorator is
>             much more than pure faceted browsing.
>             Did you have anything specific in mind in this regard?
>             Cheers
>             D.
>         -- 
>         Thanks,
>         -sherman
>         I pray that you may prosper in all things and be healthy, even
>         as your soul prospers
>         (3 John 1:2)



Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO 
OpenLink Software     Web: http://www.openlinksw.com
Received on Tuesday, 2 June 2009 15:45:25 UTC

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