eprintid: 114
rev_number: 6
eprint_status: archive
userid: 29
dir: disk0/00/00/01/14
datestamp: 2011-03-01 11:23:40
lastmod: 2011-07-11 14:33:42
status_changed: 2011-03-01 11:23:40
type: article
metadata_visibility: show
item_issues_count: 0
creators_name: Buscemi, Maria Grazia
creators_name: Montanari, Ugo
creators_id: m.buscemi@imtlucca.it
creators_id: 
title: QoS Negotiation in Service Composition
ispublished: pub
subjects: QA75
divisions: CSA
full_text_status: none
keywords: Process calculi; Service oriented computing; Constraint-based models
note: Copyright © 2010 Elsevier Inc. All rights reserved. 
The 2nd Workshop on Formal Languages and Analysis of Contract-Oriented Software (FLACOS’08) 
abstract: 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.
date: 2011
date_type: published
publication: Journal of Logic and Algebraic Programming
volume: 80
number: 1
publisher: Elsevier
pagerange: 13-24
id_number: doi:10.1016/j.jlap.2010.04.001 
refereed: TRUE
issn: 1567-8326
official_url: http://www.sciencedirect.com/science/article/B6W8D-4YWC12P-1/2/fba4154ba8acf9941004daea9925e884
citation:   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)