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QoS Negotiation in Service Composition

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)

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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.

Item Type: Article
Identification Number: 10.1016/j.jlap.2010.04.001
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
URI: http://eprints.imtlucca.it/id/eprint/114

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