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[db2triples] Implementation of R2RML and Direct Mapping : questions and comments

From: Julien Homo <jhomo@antidot.net>
Date: Mon, 9 Apr 2012 22:42:23 +0200
Message-ID: <CALRhJOhqvgsaSh5sCYiS2qX=vD1G9gQbep0-yLfd=okW0bBF_A@mail.gmail.com>
To: public-rdb2rdf-comments@w3.org
Dear RDB2RDF's Working Group's members,

I'm currently working on the new version of db2triples which is an
implementation registred with the W3C of the two standards R2RML and Direct

This version supports the two W3C Candidate Recommendation of 23 February
2012 and I'm trying to test it using W3C official test cases.
A vast majority of them are valited on my local machine and I want to send
you my technical report in accordance with procedure described at

However, I have some difficulties particularly for Phase 4 "Run the TH
software against your Test Results". I know the TH software is available
only for the DirectMapping but it doesn't work on my DM tests either.
My ts.ttl file is modified with the location where the Test Suite with test
results are stored.
In this folder, all the subdirectories (with name like "DXXX-xxx") contains
a TURTLE file directGraph-db2triples.ttl but I have this error message :

    at org.rdb2rdf.testcase.th.TCScanner.scan(TCScanner.java:128)
    at org.rdb2rdf.testcase.th.TCScanner.main(TCScanner.java:199)
    at org.rdb2rdf.testcase.th.TCScanner.scan(TCScanner.java:143)
    at org.rdb2rdf.testcase.th.TCScanner.main(TCScanner.java:199)"

Have you any idea about this problem ?

About my tests and the Test Cases, I have executed all SQL scripts into a
MySQL and a PostgreSQL database and I have some questions and comments too

- My R2RMLTC0009c and R2RMLTC0009d tests fail because mapping was
successfull with unamed column on the two dbms : why any columns in the
SELECT list derived by projecting an expression like an expression with
keyword COUNT must be named ?
Is it to conform to Core SQL 2008 ? Besides in the second test, an implicit
integer datatype is associated with SPORTCOUNT column but this is not the
case in your result. A simple cast to string is required for this column ?

- R2RMLTC00016e and DirectGraphTC0016 tests fail :  I have to modify SQL
input file in order to postgreSQL does not raise a syntax error. Indeed, on
the one hand BINARY VARYING is an unknown datatype for postgreSQL (bytea
data type allows storage of binary strings,
http://www.postgresql.org/docs/9.1/static/datatype-binary.html). On the
other hand, encoding characters like "\ux2F" instead of "/" are not
recognized. Is necessarily strictly adhere to the syntax of the SQL query to
validate this test or these requests can be adapted ?

- Finally I spotted some misprints in the Test Cases :

* R2RMLTC0014c : in the expected result, the datatypes of these generated
literals have to be switched :

<http://example.com/emp/7369> <http://example.com/emp/7369>
<http://example.com/emp#deptNum> <http://example.com/emp#deptNum> "10"^^
<http://example.com/emp/7369> <http://example.com/emp/7369>
<http://example.com/dept#deptno> <http://example.com/dept#deptno> "10"^^

* R2RMLTC0016b and DirectGraphTC0016 : You use canonical RDF lexical form
for double datatypes like "80.25E0" but it's "8.025E1" that appears in
DirectGraphTC0016. R2RML CR indicates the choice of lexical form is
but my test fails because these results are not homogeneous. Can you
confirm this expected result ?

* R2RMLTC0014b : the inverseExpression contains a delimiter idenfier with
double quotes "deptId" whereas no quotes are required (and RDF parser

* R2RMLTC00016e : IRI built from binary data seem to be not base64 encoded
contrary to the DirectGraphTC0016 test.

Thank you very much for the help you can give me , I am available for any
other question.

Best regards,

Julien Homo

Julien Homo ( @julien_homo <https://twitter.com/#%21/julien_homo>) -
Development Engineer / Technical consultant
Mail : jhomo@antidot.net - Phone : (+33 / 0)
Received on Tuesday, 10 April 2012 13:00:27 GMT

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