1. Reactive Policies for the Semantic Web*
Piero A. Bonatti Universita di Napoli Federico II, Italy Philipp Kärger L3S Research Center, Hannover, Germany Daniel Olmedilla Telefonica R&D, Madrid, Spain
* The authors' efforts were partly funded by the European COST Action IC0801 ``Agreement Technologies''
Philipp Kärger - L3S Research Center
17/01/19

2. Outline Motivation for reactive policies Background
(non-reactive) Semantic Web policies
Trust Negotiation
Reactive Semantic Web Policies
Implementation: Reactive Policies on Skype
Future Work and Conclusions
Philipp Kärger - L3S Research Center
17/01/19

3. Philipp Kärger - L3S Research Center
17/01/19

4. Behavior on the Semantic Web
limited support for semantic behavior definition
rather focus on static knowledge
typically expressed by Semantic Web policies
Rei: has(X, right(service, graduateStudent(X, ’UMBC’)))
Protune: allow(buy(Resource))  credential(C), valid_credit_card(C), accepted_credit_card(C).
KAoS: It is permitted for actor X to perform action Y in context Z.
Philipp Kärger - L3S Research Center
17/01/19

5.  Reactive Semantic Web Policies
rather focused on access control and trust
not easy to express something like
Events (not just requests)
reactions and “restricted” allowance (not just allow/deny)
some sort of reasoning
 Reactive Semantic Web Policies
“A call on Skype from an untrustworthy person shall be blocked and turned into a chat.”
Philipp Kärger - L3S Research Center
17/01/19

6. Background
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17/01/19

7. Semantic Web Policies
“declarative description of the behavior of a system”
well-defined semantics
shared vocabulary
distributed evidences
allow(read(“slides.ppt”),User)  isStudent(User).
isStudent(Person)  credential(Person, Credential),
Credential.issuer = “uni−hannover”, Credential.type = “studentid “.
Philipp Kärger - L3S Research Center
17/01/19

8. Trust Negotiation establishes trust with strangers
university
student
Trust Negotiation
establishes trust with strangers
collaborative fulfillment of the parties’ policies
evidences are collected and shared
Philipp Kärger - L3S Research Center
17/01/19

9. Reactive Semantic Web Policies
A language for
Reactive Semantic Web Policies
Philipp Kärger - L3S Research Center
17/01/19

10. Event Condition Action rules
borrowing an old idea: ON event IF condition DO action
ON a skype call arrives
IF caller is a student and it is not Wednesday
DO turn call into a chat
ON callArrives(Time,Call,Caller)
IF isStudent(Caller) not isWednesday(Time)
DO turnCallIntoChat(Call,Caller)
Philipp Kärger - L3S Research Center
17/01/19

11. ON callArrives(Time,Call,Caller)
IF isStudent(Caller) not isWednesday(Time)
DO turnCallIntoChat(Call,Caller)
Event definition rules
Action definition rules
Implication rules
callArrives(X,Y,Z)  callArrivesOnSkype(X,Y,Z).
turnCallIntoChat(Call,User)  cancelCall(Call), openChat(User).
isStudent(Person)  credential(Person, Credential),
Credential.issuer = “uni−hannover”, Credential.type = “studentid “.
Philipp Kärger - L3S Research Center
17/01/19

12. Semantics ON callArrives(Time,Call,Caller)
IF isStudent(Caller), not isWednesday(Time)
DO turnCallIntoChat(Call,Caller)
callArrives(X,Y,Z)  callArrivesOnSkype(X,Y,Z).
turnCallIntoChat(Call,User)  cancelCall(Call), openChat(User).
isStudent(Person)  credential(Person, Credential),
Credential.issuer = “uni−hannover”, Credential.type = “studentid “.
Philipp Kärger - L3S Research Center
17/01/19

13. Strong and lightweight evidences
Strong evidences
digitally signed credentials
Lightweight evidences
unproven facts like
a license agreement
age or address (html forms)
password
data gathered from the Semantic Web
isStudent(Person)  credential(Person, Credential),
Credential.issuer = “uni−hannover”, Credential.type = “studentid “.
isAdult(Person)  declaration(Person, Age),
Age > 18.
isFOAFFriend(Person) 
in([Friend], FOAFWrapper : getFOAFFriends()),
Person = Friend.
Philipp Kärger - L3S Research Center
17/01/19

14. Integration of (Semantic) Web sources
isFOAFFriend(Person) 
in([Friend], FOAFWrapper : getFOAFFriends()),
Person = Friend.
Philipp Kärger - L3S Research Center
17/01/19

15. Reactive Semantic Web Policies - Summary
declarative policy language for reactive policies
well-defined semantics
strong and lightweight evidences
seamless integration of (Semantic) Web sources
Philipp Kärger - L3S Research Center
17/01/19

16. SPoX – Skype Policy Extension
Implementation
SPoX – Skype Policy Extension
Philipp Kärger - L3S Research Center
17/01/19

17. Philipp Kärger - L3S Research Center
17/01/19

18. SPoX – a Skype Policy Extension
“Driving the behavior of Skype”
Reactive policies define
who is allowed to do what
which/whose notification shows up
considers the Social Context
Skype is extended by
a reactive policy engine
connector to (Semantic) Web sources
channel for negotiations
Philipp Kärger - L3S Research Center
17/01/19

19. Defining Reactive Policies in SPoX
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17/01/19

20. Architecture of SPoX
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17/01/19

21. Strong and lightweight evidences in action
Strong evidences
credentials are shared through the game channel
Lightweight evidences
used to identify people across Social Networks
used to transfer passwords
Philipp Kärger - L3S Research Center
17/01/19

22. Conclusions & Future Work
Philipp Kärger - L3S Research Center
17/01/19

23. Future Work exploit authentication means (OpenID, FOAF+SSL, etc.)
integrate other Semantic Web sources
handle conflicting policy rules
Philipp Kärger - L3S Research Center
17/01/19

24. Conclusions
Reactive behavior description and trust features are isolated on the Semantic Web
Reactive Semantic Web policies combines both:
reactive rule reasoning and
upper layers of trust on the SW stack
Provided a framework for reactive Semantic Web policies
establishes trust based on exchange of evidences
features formal language definition
Provided Implementation for the semantic behavior control in Skype
Philipp Kärger - L3S Research Center
17/01/19

25. Thanks for your attention.
Philipp Kärger
L3S Research Center
Philipp Kärger - L3S Research Center
17/01/19