Formation de coalitions pour une composition de
services Web fond´
ee sur la confiance dans les r´
eseaux
sociaux
Amine Louati1 Joyce El Haddad 2 Suzanne Pinson2
1Institut mines T´el´ecom, T´el´ecom ´Ecole de Management, LITEM, France 2PSL, Universit´e Paris-Dauphine, LAMSADE CNRS UMR 7243, France
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
6 Conclusion and Perspectives
Motivation
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
Motivation
Motivation
Service Composition
Satisfies a complex user needswhich cannot be achieved by an atomic service
Allows the definition of value addedapplications, which have the potential to reduceeffort and time of development [Ponn 02]
Motivation
The model : a multi-agent model
Able to performcomplex and distributed tasks
Support different forms of interactionincluding negotiation and coordination
Capable to extract and interpret information
Existing multi-agent approaches
Planning (graph, state, actions) [Paik 06, Ponn 02, Siri 04, Tong 11, Xu 11]
Coordination (reasoning, roles, negotiation) [Charif 13, Siala 11, Wang 06, Maam 05]
Cooperation (organization, preferences, sociability) [Grif 03, Ermo 03, Mull 06, Hong 09, Bour 09]
Motivation
Proposition : a coalition formation process
Challenges
How to integrate social dimension in the coalition process ⇒ Social trust model
How to ensure providers autonomy to decide with whom to cooperate ⇒ Endow agents with the ability to participate in the coalition process according to theirpreferences
How to enable agents to leave coalition when they are not satisfied ⇒ Definition of anincremental, dynamic and overlapping protocol for member selection
Background
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
Background
Concepts Definitions
Social network : Given a set A = {a1, a2, ..., al} of agents and a set
E ⊆ A × A of edges, a social network is a connected graph
G =< A, E > where an edge (ak, aj) ∈ E represents an asymmetric
trust relationship between ak and aj
Agent: An agent ak ∈ A is an autonomous entity such that
ak =< Sk, Trust, ET , CT , λInfk, λSupk, βk, Blistk >
Service: A service s is a tuple such as s = (in, out, f , q1, q2, q3)
Louati, A., El Haddad, J., Pinson, S.
A Multilevel Agent-based Approach for Trustworthy Service Selection in Social Networks in IAT 2014 3 a a6 a8 a9 10 a 1 a 2 a a5 4 a 11 a a7 12 a requester i a agent
Background
Concepts Definitions
User query : Let F be the definition domain of available
functionalities. A user query Q = {f1, f2, . . . , fn| ∀1 ≤ i ≤ n, fi ∈ F } is
a finite set of functionalities
Coalition: Let Q be a user query. A coalition
c = {(f1, x1), . . . , (fi, xi), . . . , (fn, xn) | ∀i ∈ [1, n], ∃k ∈ [1, s] such as
xi = ak et ak ∈ Ai} is a set of agents that satisfy Q.
Q={f1, f2, f3} 2 a 4 a 12 a c1
Background
Multi-agent model
Candidate (provider agent) Broker (requester agent) Member (provider agent) Trust model Trust model Trust model User queryFigure –A broker-based multi-agent model for dynamic service composition
Agents cooperate to satisfy complex user’s needs based on decentralized decision makingguided by trust in cooperation
Trust model
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
Trust model
Trust
Trust in cooperation CT (ak, aj) = ( 1 if NbSollk[j ] = 0 NbMemk[j ] NbSollk[j ] otherwiseLevel of reliability of a candidate aj according to a member ak based on
their history of cooperation
Trust in coalition
evalC (ak, cz) =
P
at∈czCT (ak, at)
|cz|
Degree of satisfaction of a candidate ak to join a coalition cz
Coalition formation process description
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
Coalition formation process description
Service discovery and selection process
Coalition formation process description
Coalition formation process description
Service discovery and selection process
Coalition formation process description
Coalition formation process description
Coalition formation process description
Sequentialprocess composed of three phases :
1 Initial Coalitions Generation (e.g. C = {c1 = {a2}, c2= {a6}})
2 Member Selection
3 Best coalition choice c ← Argmax 1≤z≤|C|
P
at ∈czET (at)
|cz|
Coalition formation process description
Coalition formation process description
Sequentialprocess composed of three phases :
1 Initial Coalitions Generation (e.g. C = {c1 = {a2}, c2= {a6}}) 2 Member Selection
3 Best coalition choice c ← Argmax 1≤z≤|C|
P
at ∈czET (at)
Coalition formation process description
Coalition formation process description
Sequentialprocess composed of three phases :
1 Initial Coalitions Generation (e.g. C = {c1 = {a2}, c2= {a6}}) 2 Member Selection
3 Best coalition choice c ← Argmax 1≤z≤|C|
P
at ∈czET (at)
|cz|
Experimental Results
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
Experimental Results
Experimental methodology
```` ```` ```` `` Configuration Scenario A B C D E User query 2 3 4 5 6 services 5 5 5 5 5 timeout (ms) 3000 3000 3000 3000 3000Table –Definition of test scenarios
Experimental Results
Performance of the coalition process
A B C D E 0 % 20 % 40 % 60 % 80 % 100 % 100100100 10098 100100 100100 100100 89 93 88 67 58 67 71 57 46 0 0 27 10 18 0 0 0 0 3 Test scenario P ercentage of generated coalitions
5 coalitions 4 coalitions 3 coalitions 2 coalitions 1 coalition 0 coalition
Figure –Percentage of generated
coalitions per test scenario
A B C D E 0 2 4 6 0 0 0.6 1.6 4.45 Test scenario Average frequency of abandon
Figure –The average frequency of
Conclusion and Perspectives
Outline
1 Motivation
2 Background
3 Trust model
4 Coalition formation process description
5 Experimental Results
6 Conclusion and Perspectives
Conclusion and Perspectives
Conclusion
Trust-based dynamic coalition formation process for service composition in social networks
Incremental, dynamic and overlapping selection protocol
Agent cooperate based on a decentralized decision-making process guided by trust in cooperation
Conclusion and Perspectives
Perspectives
More experimentation
Investigate the correlation between the quality of the chosen composite service and the trustworthiness of its members
Analyze the impact of the variation of the maximum layer value on the coalition formation process
Integrate negotiation in the coalition formation process : persuasions strategies
Examine the coalition stability : parallel coalition generation and define the utility of a service composition
Conclusion and Perspectives