1,720,998 research outputs found
Optimization of adaptation plans for a service-oriented architecture with cost, reliability, availability and performance tradeoff
No full textA service-based system may require adaptation for several reasons, such as service evolution (e.g., a new version may be available), hardware volatility (e.g., network quality changes), and varying user demands and new requirements (e.g., a new functionality or a different level of quality of service). Therefore, it is suitable to dynamically adapt a service-based system in an automated manner. However, service adaptations often do not consider software quality attributes and, if they do, they relay on a single attribute in isolation. In this paper, we present an optimization model, which aims to minimize the adaptation costs of a Service-Oriented Architecture (SOA), in correspondence with a certain change scenario (i.e., a set of new requirements) under reliability, availability and performance tradeoff. The model predicts the quality of the new SOA obtained by changing both its structure and behavior. Specifically, it suggests how to replace existing services with available instances and/or adding new services, and how to remove or introduce interaction(s) between existing services and/or new services. We show how our model works on a smartphone mobile application example, and through the sensitivity analysis we highlight its potential to drive architectural decisions
A QoS-based framework for the adaptation of service-based systems
No full textSince a system may require dynamic adaptation for several reasons (e.g., a new version may be available and a new functionality or a different level of quality of service) it should be possible to dynamically adapt a service-based system in an automated manner. In this paper we give a general overview of the main components of a framework, based on an optimization model, that dynamically adapts a service based system (i.e., both the structural and behavioral software and hardware architecture) while minimizing the adaptation costs and guaranteeing a required level of the system qualities. Adaptation actions can be triggered both by a user request and/or automatically after the runtime violation of system quality constraints, or the appearing/disappearing of services into the environment. In this paper we provide also a deeper discussion of the optimization model that is the core of the framework by providing an example of instantiation of the model together with a first experimentation
Architectural decisions for HW/SW partitioning based on multiple extra-functional properties
No full textGrowing advances in hardware technologies are enabling significant improvements in application performance by the deployment of components to dedicated executable units. This is particularly valid for Cyber Physical Systems in which the applications are partitioned in HW and SW execution units. The growing complexity of such systems, and increasing requirements, both project- and product-related, makes the partitioning decision process complex. Although different approaches to this decision process have been proposed during recent decades, they lack the ability to provide relevant decisions based on a larger number of requirements and project/business constraints. A sound approach to this problem is taking into account all relevant requirements and constraints and their relations to the properties of the components deployed either as HW or SW units. A typical approach for managing a large number of criteria is a multicriteria decision analysis. This, in its turn, requires uniform definitions of component properties and their realization in respect to their HW/SW deployment. The aim of this paper is twofold: a) to provide an architectural metamodel of component-based applications with specifications of their properties with respect to their partitioning, and b) to categorize component properties in relation to HW/SW deployment. The metamodel enables the transition of system requirements to system and component properties. The categorization provides support for architectural decisions. It is demonstrated through a property guideline for the partitioning of the System Automation and Control domain. The guideline is based on interviews with practitioners and researchers, the experts in this domain
A QoS-based framework for the adaptation of service-based systems
No full textSince a system may require dynamic adaptation for several reasons (e.g., a new version may be available and a new functionality or a different level of quality of service) it should be possible to dynamically adapt a service-based system in an automated manner. In this paper we give a general overview of the main components of a framework, based on an optimization model, that dynamically adapts a service based system (i.e., both the structural and behavioral software and hardware architecture) while minimizing the adaptation costs and guaranteeing a required level of the system qualities. Adaptation actions can be triggered both by a user request and/or automatically after the runtime violation of system quality constraints, or the appearing/disappearing of services into the environment. In this paper we provide also a deeper discussion of the optimization model that is the core of the framework by providing an example of instantiation of the model together with a first experimentation
Quantifying the influence of failure repair/mitigation costs on service-based systems
No full textThe analysis of non-functional properties of Service-Based Systems (SBSs) is a complex task, mostly because it requires models that encompass the composition of service properties into architectural properties. For example, the reliability of a SBS is given by the composition of service and interconnection reliabilities. Although several approaches have been introduced in the last few years to address these issues, the tradeoff analysis among non-functional properties of software services has not yet been studied enough. The goal of this paper is to introduce a set of optimization models that allow quantifying the costs of service failure repair/mitigation actions aimed at keeping the whole SBS reliability over a certain threshold. On the basis of our previous work in this area, we first introduce an optimization model aimed at selecting either in-house built or provided services with the goal of minimizing the SBS cost while guaranteeing a certain level of reliability. Thereafter we strengthen the reliability constraints, and we build two different optimization models that aim to solve the same problem under new constraints, where one model starts from the solution obtained in the original model and tries to improve it, while the other one looks for an optimal solution in the whole search space. Finally, we introduce a fourth model, based on stochastic optimization, with the goal of rather searching for solutions that explicitly take into account the stochastic nature of the problem and search for new repair/mitigation actions cheaper than the ones identified by the other models. Each optimization model has been experimented on about 300 variations of a nominal model. The experimental results show the efficacy of our optimization models to quantify the costs of different failure repairing/mitigation actions in different contexts
Resource Allocation, Trading and Adaptation in Self-Managing Systems
No full textThe allocation of a limited number of resources among multiple selfinterested
stakeholders is a challenging issue for many real life systems and applications. Resource management for this type of systems is a challenging
task because of the different objectives of the owner of the resources and the
stakeholders. The owner aims to an efficient usage of the resources, while
stakeholders have self-interested objectives. This paper presents a software framework for resource management based on the integration of dynamic allocation, trading, and self-adaptation mechanisms. Resource allocation and adaptation are performed in a centralized manner, while resource trading is achieved through a decentralized approach. Furthermore, the paper presents the application of the proposed framework in two different domains: aeronautics and Internetware
An Optimization Process for Adaptation Space Exploration of Service-oriented Applications: the Stock Trading System case study
Full text linkWe propose an automatic optimization process for adaptation space exploration of service-oriented applications based on trade-offs between functional and extra-functional requirements. The optimization method combines both metaheuristic search techniques and functional/extra-functional patterns (i.e., architectural design patterns and tactics). Moreover, the proposed methodology relies also on the standard Service oriented Component Architecture(SCA) for heterogeneous service assembly and related tools/running infrastructures in order to process architectural models (of the application to adapt) that are directly tight to the real assembled components implementations and their deployment. As a proof-of-concepts, this report provides an example of instantiation of the proposed process together with an experimentation on a stock trading application
Adaptation space exploration for service-oriented applications
No full textService-oriented applications may require adaptation to tackle changing user needs, system intrusions or faults, changing operational environment, resource variability, etc. In order to achieve the right trade off among the functional requirements, software qualities (such as performance and reliability) and the adaptation cost itself, the adaptation decisions should involve the (a priori) evaluation of new alternatives to the current application design. However, the generation and evaluation of design alternatives is often time-consuming, it can be error-prone and can lead to suboptimal design decisions, especially if carried out manually by system maintainers.
This article proposes an automatic optimization process for adaptation space exploration of service-oriented applications based on trade-offs between functional and extra-functional requirements. The proposed method combines the use of metaheuristic search techniques and functional/extra-functional patterns (i.e., architectural design patterns and tactics). Besides, the proposed methodology relies on the standard Service Component Architecture (SCA) for heterogeneous service assembly and its runtime platforms. As a proof-of-concept, this article provides also an example of instantiation of the process together with an experimentation on a sample application and a numerical evaluation of the scalability of the approach
An Optimization Process for Adaptation Space Exploration of Service-oriented Applications
No full textThis paper proposes an automatic optimization process for adaptation space exploration of service-oriented applications based on trade-offs between functional and extra-functional requirements. The optimization method combines both meta-heuristic search techniques and the use of functional/extra-functional patterns (i.e., architectural design patterns and tactics). Moreover, the proposed approach relies on the standard Service-oriented Component Architecture (SCA) for heterogeneous service assembly and its runtime platforms
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