relation: http://eprints.imtlucca.it/114/
title: QoS Negotiation in Service Composition
creator: Buscemi, Maria Grazia
creator: Montanari, Ugo
subject: QA75 Electronic computers. Computer science
description: 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.
publisher: Elsevier
date: 2011
type: Article
type: PeerReviewed
identifier:   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)  
relation: http://www.sciencedirect.com/science/article/B6W8D-4YWC12P-1/2/fba4154ba8acf9941004daea9925e884
relation: doi:10.1016/j.jlap.2010.04.001