LDOW2012
Lyon,
16
April
Linked Data Access
Goes Mobile"
Context-Aware Authorization for Graph Stores!
SELECT … !
WHERE {…}!
Luca
Costabello,
Serena
Villata
Nicolas
Delaforge,
Fabien
Gandon

Key Features"
Background!
WAC, [Abel et al, ISWC2007], [Finin et al.,SACMAT2008],[Flouris et al., FIS2010],
[Sacco and Passant, LDOW2011], [Toninelli et al, ISWC2006]!
Semantic Web Pluggable to
languages only" any RDF store!
> No new Policy languages! > SPARQL 1.1!
Granularity from Mobile context in
triples to whole graphs! the loop!
> Named Graphs! > Context Awareness!
[Carroll
et
al,
WWW2005]
[Schilit
and
Theimer,
94]
RDF
1.1
[Dey,
01]
2

How it Works – Initial Setup"
● Named Graph Partitioning!
!
● Access Policy Definition!
!S4AC & PRISSMA Vocabularies!
3

Sample Access Policy"
Protected resource
Conditions
to verify
4

How it Works"
1. Query Contextualization ! !!
INSERT DATA { ! SELECT … ! U
+
GRAPH :ctx1{! WHERE {…}! P
[!
!
!
U P
,! ]!
,! , …!
:ctx1!
}}!
5

How it Works"
2. Access Policy Evaluation!
ASK {?context !
a prissma:Context; !
prissma:environment ?env.!
?env prissma:currentPOI ?poi. !
?poi prissma:radius "500";!
foaf:based_near ?p. !
=
"false"
?p geo:lat "43.615811";!
geo:long "7.068532".} !
BINDINGS ?context {(:ctx1)}!
U
P 6

How it Works"
3. Query Execution on Accessible Named
Graphs!
:ng1 ! :ng2 !
SELECT … ! :ng3 !
WHERE {…}!
SELECT …!
FROM :ng2,:ng3!
FROM NAMED :ng2,:ng3!
WHERE {…}!
7

Response Time Evaluation"
RDF
store
and
SPARQL
1.1.
engine:
Corese-­‐KGRAM
with
Berlin
SPARQL
Benchmark
Dataset
3.1
• Dataset size still predominant!
• More context updates, !
more consumers"
à Slower!
• Small fraction granted"
à Faster!

Future Work"
Privacy"
Context data User-centered
trustworthiness" evaluation"
Luca
Costabello
|
Serena
Villata
|
Nicolas
Delaforge
|
Fabien
Gandon
@lukostaz " " @serena_villata @ndelaforge" " @fabien_gandon"
tinyurl.com/shi3ld