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PROPOSAL to close ISSUE-59: DataQuery support for other query languages

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Sun, 02 Jan 2011 21:22:27 -0500
Message-ID: <4D2132E3.2080106@digitalbazaar.com>
To: RDFa WG <public-rdfa-wg@w3.org>
If there are no objections to this proposal in 7 days, we will close
ISSUE-59: DataQuery support for other query languages.


This issue concerned several assumptions that were made by the original
query interface in the RDFa API. Specifically, the issue noted that the
arguments passed to a query() method would differ based on the query
language (SPARQL vs. SQL vs. query-by-example). Some may take a query
string, others a query string and a list of arguments for values in the
query string, others may take a query string and a return template. That
is to say that there is no general interface that would work for even
the simplest query mechanisms.

During the discussion on this topic, it became evident that supporting
even simple query mechanisms using a general interface would be
problematic. A different approach was suggested, which was to allow
different query mechanisms to extend the DocumentData interface. The
RDFa API would provide a basic query mechanism that would result in a
sequence of Projections:

   query(in object? query, in optional object template);

The method above could be accessed via the following interface:


However, if a new query mechanism were to be created, it could extend
the DocumentData interface. For example, a SPARQL query interface could
be defined like so:


Alternatively, a library could just utilize the underlying RDF data
model provided by document.data.rdf and use its own query mechanism:


The proposal is to not support a generalized DataQuery interface because
a general mechanism for querying does not exist. Rather, general
interfaces to the RDF data are provided, which developers may build on
top of as new query mechanisms are discovered.

Please comment in 7 days from this post if you object to this proposal.
If there are no objections within 7 days, ISSUE-59 will be closed.

-- manu

Manu Sporny (skype: msporny, twitter: manusporny)
President/CEO - Digital Bazaar, Inc.
blog: Linked Data in JSON
Received on Monday, 3 January 2011 02:22:56 UTC

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