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Normative Management of Web Service Level Agreements

Service Level Agreements (SLAs) are used in Service- Oriented Computing to define the obligations of the parties involved in a transaction. SLAs define these obligations, including for instance the expected service levels to be delivered by the provider, and the payment expected from the client. The obligations of the parties must be made explicit prior…

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A Comprehensive Quality Model for Service-oriented Systems

In a service-oriented system, a quality (or Quality of Service) model is used (i) by service requesters to specify the expected quality levels of service delivery; (ii) by service providers to advertise quality levels that their services achieve; and (iii) by service composers when selecting among alternative services those that are to participate in a…

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Dealing with Quality Tradeoffs during Service Selection

In a service-oriented system (SoS) service requests define tasks to execute and quality of service (QoS) criteria to optimize. A service request is submitted to an automated service selector in the SoS, which allocates tasks to those service that, together, can “best” satisfy the given QoS criteria. When the selector cannot optimize simultaneously the given…

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Timing Nonfunctional Requirements

Analysis of temporal properties of nonfunctional – i.e., quality – requirements (NFRs) has not received significant attention. In response, this paper introduces basic concepts and techniques needed for the specification and analysis of time properties of NFRs. Jureta, I.J. and Faulkner, S., 2008, October. Timing Nonfunctional Requirements. In International Conference on Conceptual Modeling (pp. 302-311). Springer, Berlin,…

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Context-Driven Autonomic Adaptation of Service Level Agreements

Service Level Agreements (SLAs) are used in Service-Oriented Computing to define the obligations of the parties involved in a transaction. SLAs define the service users’ Quality of Service (QoS) requirements that the service provider should satisfy. Requirements defined once may not be satisfiable when the context of the web services changes (e.g., when requirements or…

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Capturing and Using QoS Relationships to Improve Service Selection

In a Service-Oriented System (SOS), service requesters specify tasks that need to be executed and the quality levels to meet, whereas service providers advertise their services’ capabilities and the quality levels they can reach. Service selectors then match to the relevant tasks, the candidate services that can perform these tasks to the most desirable quality…

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Clarifying Goal Models

Representation and reasoning about information system (IS) requirements is facilitated with the use of goal models to describe the desired and undesired IS behaviors. One difficulty in goal modeling is arriving at a shared understanding of a goal model instance, mainly due to different backgrounds of the system stakeholders who participate in modeling, and the…

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Achieving, Satisficing, and Excelling

Definitions of the concepts derived from the goal concept (including functional and nonfunctional goal, hardgoal, and softgoal) used in requirements engineering are discussed, and precise (and, when appropriate, mathematical) definitions are suggested. The concept of satisficing, associated to softgoals is revisited. A softgoal is satisficed when thresholds of some precise criteria are reached. Satisficing does…

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A More Expressive Softgoal Conceptualization for Quality Requirements Analysis

Initial software quality requirements tend to be imprecise, subjective, idealistic, and context-specific. An extended characterization of the common Softgoal concept is proposed for representing and reasoning about such requirements during the early stages of the requirements engineering process. The types of information often implicitly contained in a Softgoal instance are highlighted to allow richer requirements…