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Context-Aware Access Control and Presentation of Linked Data
My PhD Thesis defence slideshow. The work discusses the influence of mobile context in accessing Linked Data from handheld devices. The work dissects this issue into two research questions: how to enable context-aware adaptation for Linked Data consumption, and how to protect access to RDF stores from context-aware devices.
My PhD Thesis defence slideshow. The work discusses the influence of mobile context in accessing Linked Data from handheld devices. The work dissects this issue into two research questions: how to enable context-aware adaptation for Linked Data consumption, and how to protect access to RDF stores from context-aware devices.
Context-Aware Access Control and Presentation of Linked Data
1.
CONTEXT-AWARE
ACCESS CONTROL AND
PRESENTATION OF LINKED DATA
PhD Thesis Defence
Luca COSTABELLO
29 November 2013
2.
Mobile Guide
“Is it optimized for my tablet?”
“Does it have a visuallyimpaired mode?”
“Does it provide practical
information when I am on my way?”
Museum triplestore
“Paintings metadata
accessible only to on-site
visitors.”
“Museum Data accessible
this week only”
“Metadata can be edited
by employers only”
2
3.
How Does
Mobile Context Influence Linked Data Access?
Mobile Context
Model
Context-Aware
Linked Data
Presentation
Context-Aware
Linked Data
Access control
3
4.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
4
5.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
5
8.
The PRISSMA vocabulary
http://ns.inria.fr/prissma
8
9.
Example: at the museum
:atTheMuseum a prissma:Context ;!
prissma:environment :museumEnv .!
!
prissma:Context
:museumEnv a prissma:Environment ;!
:atTheMuseum
prissma:poi :museumGeo.!
!
prissma:environment
:museumGeo geo:lat "48.86034" ;!
geo:long "2.337599" ;!
prissma:Environment
prissma:radius ”200" .!
:museumEnv
!
prissma:poi
:museumGeo
geo:lat
48.86034
prissma:radius
geo:long
200
2.337599
9
10.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
10
11.
Presentation Model
• Extending Fresnel with PRISSMA
11
12.
✓
Linked Data
support
Context-awareness
✓ ✓
Standard Languages
✓
✓ ✓
✓
✓ ✓
✓
✓
✓
Runtime adaptation
✓
✓
✓
✓
✓
✓
✓
✓
✓
Multimodality
✓
Client-side only
Evaluation
PRISSMA
CSS Media
Queries
COIN
Adipat
CAMB
MIMOSA
Paternò
Butter
Chamaleon
Zhang
Chen
Laakko
NAC
Adaptive Presentation Frameworks for the Web
✓
✓
✓
✓
✓
✓
✓
✓
✓
12
13.
Declarative
approach
Domain
Independence
Standard Languages
Context Awareness
PRISSMA
Fresnel
LDVM
Hide the
Stack
LESS
Tal4Rdf
Xenon
Surrogates
Noadster
Haystack
Presentation Frameworks for the Semantic Web
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
Automatic
stylesheets
✓
Evaluation
✓
Distribution
Multimodality
✓
✓
✓
✓
13
14.
Fresnel
[Pietriga et al. 2006]
Content selection
and ordering!
Content formatting
and additional
content!
Styling instructions
for fonts, colors, and
borders!
Retrieved from [Pietriga et al. 2006]
14
19.
Examples
PRISSMA Browser for Android
Smartphone, user walking
in museum town.
Tablet, user at home.
19
20.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph
Matching for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
20
27.
Prism Selection: Search Algorithm!
1. Compute context units
isomorphisms costs
prissma:environment
:ActualCtx
1
2
3
4
5
6
7
8
9
foreach context unit S in D do!
compute_subgraph_isomorphisms(S,GI)!
!
C=0!
while C(fcheapest)< T { !
if S1 is Prism then!
prissma:Context
R.add(S1)!
0
!
foreach child of S1 do!
fchild= combine(fS1,fS2)!
10
11
prissma:poi
:actualPOI
:actualEnv
geo:lat
prissma:radius
geo:long
10
}!
return R!
48.843453
2.32434
C=0.34
!
C=0!
:museumGeo
prissma:radius
geo:lat
geo:lon
200
48.86034
-2.337599
1
prissma:Environment
2
{3,1,2,{prissma:poi}}
:atTheMuseum
{4,0,3,{prissma:environment}}
27
28.
Prism Selection: Search Algorithm!
prissma:environment
:ActualCtx
1
2
3
4
5
6
7
8
9
foreach context unit S in D do!
compute_subgraph_isomorphisms(S,GI)!
!
C=0!✓
while C(fcheapest)< T { !
if S1 is Prism then!
prissma:Context
R.add(S1)!
0
!
foreach child of S1 do!
fchild= combine(fS1,fS2)!
10
11
prissma:poi
:actualPOI
:actualEnv
geo:lat
prissma:radius
geo:long
10
}!
return R!
48.843453
2.32434
C=0.34
!
C=0!✓
✓
:museumGeo
prissma:radius
geo:lat
geo:lon
200
48.86034
-2.337599
1
prissma:Environment
2
C=0.17! ✓
{3,1,2,{prissma:poi}}
T=0.6!
C=0.09! ✓
2. Combine costs
:atTheMuseum
{4,0,3,{prissma:environment}}
28
29.
Evaluation: Memory Consumption
250
20
Memory [KB]
25
Decomposition Items
300
200
150
100
50
0
0.1
0.3
0.5
0.7
0.9
Percentage of common context units
Total decomposition Items
Context Units (decomposition)
Context Units (raw prisms)
15
10
5
0
0.1
0.3
0.5
0.7
0.9
Percentage of common context units
PRISSMA decomposition
Jena Models
29
30.
Evaluation: Response Time
→
If prisms are completely different
if prisms are highly
similar
30
31.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
31
38.
Outline
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control
38
39.
Enforcing Access Control
• The Shi3ld Framework
39
40.
Shi3ld Framework
SPARQL (Shi3ld-SPARQL)
[ECAI 2012]
SELECT … !
WHERE {…}!
GET /data/resource HTTP/1.1!
HTTP Operations (Shi3ld-HTTP)
[ESWC 2013]
• SPARQL Graph Store Protocol (GSP)
• Linked Data Platform (SPARQL-less)
40
41.
Authorization Procedure
1. Adding Client Attributes to the Query (SPARQL)
SELECT … !
WHERE {…}!
+
INSERT DATA { !
GRAPH :ctx1{…}
}!
:ctx_AC1
p:user p:environment
Context
user
device environment
Device
Environment
:env_AC1
<http://carl-johnson.org#me>
p:nearbyEntity
User
p:nearbyEntity
"male"
foaf:gender
<http://alice.org#me>
41
42.
Authorization Procedure
1. Adding Client Attributes to the Query (HTTP)
GET /data/resource HTTP/1.1!
Host: example.org!
!
Authorization: Shi3ld <...>!
:ctx_AC1
Context
p:user p:environment
user
device environment
User
Device
Environment
:env_AC1
<http://carl-johnson.org#me>
p:nearbyEntity
p:nearbyEntity
"male"
foaf:gender
<http://alice.org#me>
42
44.
Authorization Procedure
3. Response Construction (SPARQL)
:ng1!
:ng3!
:ng2!
SELECT … !
WHERE {…}!
SELECT …!
FROM :ng2,:ng3!
WHERE {…}!
44
45.
Authorization Procedure
3. Response Construction (HTTP)
401 Unauthorized!
45
46.
Response Time Evaluation (Shi3ld-SPARQL)
Corese-KGRAM SPARQL Engine 3.0.14 with Berlin SPARQL Benchmark Dataset 3.1
Dataset size still predominant
Small fraction access granted → Faster
More context updates, more consumers → Slower
46
47.
Response Time Evaluation (Shi3ld-HTTP)
Jena Fuseki 0.2.6 (Shi3ld-GSP), Corese-KGRAM 3.0.14 (Shi3ld-LDP)
• Response time linear w/ AC number
• Shi3ld-HTTP SPARQL-less: 25% faster
• AC complexity does not affect
response time
47
49.
How Does
Mobile Context Influence Linked Data Access?
1
Mobile Context Model
2
Presentation Model
3
Error-Tolerant Subgraph Matching
for Context Graphs
4
Access Control Model
5
Enforcing Access Control with
Web Standards
49
50.
Limitations and Open Issues
1
Mobile Context Model
2
Presentation Model
3
Prisms Distribution: Linked
Presentation-level Metadata.
Machine learning to optimize cost
functions parameterization.
Error-Tolerant Subgraph Matching
for Context Graphs
User acceptability evaluation
campaign.
4
5
Access Control Model
Enforcing Access Control with
Web Standards
Explanation mechanism for
“access denied” responses.
Trustworthiness of Client
Context
Deeper privacy-preserving
mechanism.
50
51.
Perspectives
Context-based Linked Data Discovery
Enhanced Information Retrieval for mobile users
Web of Data interlinking
51
52.
• L. Costabello. PRISSMA, Towards Mobile Adaptive Presentation of the Web of Data.
Doctoral Consortium, ISWC 2011.
• L. Costabello, S. Villata, N. Delaforge and F. Gandon. Linked Data Access Goes Mobile:
Context-Aware Authorization for Graph Stores, LDOW 2012.
• L. Costabello, S. Villata and F. Gandon. Context-Aware Access Control for RDF Graph
Stores. ECAI 2012.
• S. Villata, L. Costabello, N. Delaforge and F. Gandon. A Social Semantic Web Access
Control Model. Journal on Data Semantics, Springer, 2013.
• L. Costabello, S. Villata. O. Rodriguez-Rocha and F. Gandon. Access Control for HTTP
Operations on Linked Data, ESWC 2013.
PRISSMA
wimmics.inria.fr/projects/prissma
Shi3ld
wimmics.inria.fr/projects/shi3ld
http://luca.costabello.info
Thanks
52