Buscemi, Maria Grazia and Montanari, Ugo QoS Negotiation in Service Composition. Journal of Logic and Algebraic Programming, 80 (1). pp. 13-24. ISSN 1567-8326 (2011)Full text not available from this repository.
Service composition in Service Oriented Computing concerns not only integration of heterogeneous distributed applications but also dynamic selection of services. Quality of Service (QoS) plays a key role in service composition as services providing the same functionalities can be differentiated according to their QoS guarantees. At subscription time, a service requester and a provider may sign a contract recording the QoS of the supplied service. The cc-pi calculus has been introduced as a constraint-based model of QoS contracts. In this work we propose a variant of the cc-pi calculus in which the alternatives in a choice rather than being selected non-deterministically have a dynamic priority. Basically, a guard cj:πj in a choice is enabled if the constraint cj is entailed by the store of constraints and the prefix πj can be consumed. Moreover, the j-th branch can be selected not only if the corresponding guard cj:πj is enabled but also if cj is weaker than the constraints ci of the other enabled alternatives. We prove that our choice operator is more general than a choice operator with static priority. Finally, we exploit some examples to show that our prioritised calculus allows arbitrarily complex QoS negotiations and that a static form of priority is strictly less expressive than ours.
|Additional Information:||Copyright © 2010 Elsevier Inc. All rights reserved. The 2nd Workshop on Formal Languages and Analysis of Contract-Oriented Software (FLACOS’08)|
|Uncontrolled Keywords:||Process calculi; Service oriented computing; Constraint-based models|
|Subjects:||Q Science > QA Mathematics > QA75 Electronic computers. Computer science|
|Research Area:||Computer Science and Applications|
|Depositing User:||Users 29 not found.|
|Date Deposited:||01 Mar 2011 11:23|
|Last Modified:||11 Jul 2011 14:33|
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