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The shift in software engineering from the design, implementation and management of isolated software elements towards a network of autonomous interoperable service is calling for a shift in the way software is designed. We propose the use of the agent-oriented methodology Tropos for the analysis of web service requirements. We show how the Tropos...
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Citations
... i* does recognize the importance of the force of a dependence by allowing three possible levels of force: critical, committed and open [1]. But, as discussed in the sequel, it turns out that in several areas of research, people have opted for defining specializations of social dependence relationships where the strength of dependence is built into their semantics. ...
... The use of i* to build requirement models for services goes back to Diana Lau's Masters thesis at the University of Toronto, presented in [6], but also [1] and [9]. All three proposals use the Tropos methodology [3] for deriving agentoriented implementations from stakeholder requirements. ...
Social dependance relationships were used in the i* requirements modelling language to represent dependencies among social actors. We study the evolution of the notion of social dependency into that of commitment in the Azzurra specification language for business processes, and then into the notions of obligation and power in the Symboleo specification language for legal contracts. Our account focuses on the difference in the semantics of these relationships, the language used to talk about them, and how appropriate they are for capturing requirements for services.
... In the Web services domain, autonomous services depend on one another for their functioning hence their reliability is crucial for proper functioning of the entire system [4]. In addition, service requester may decide on the use of a particular service depending on the level of its reliability [5,6]. ...
... In the Web services domain, autonomous services depend on one another for their functioning hence their reliability is crucial for proper functioning of the entire system [4]. In addition, service requester may decide on the use of a particular service depending on the level of its reliability [5,6]. ...
... In the context of Web services, considerations of the QoS attributes are crucial for a number of reasons: firstly, self-governing administrations rely upon each other for their working and they should know about one another's QoS; secondly, a service consumer may settle on the use of a particular Web servicedepending on its non-functional properties. Similarly, a service provider may provide similar function with a dissimilar QoS, for example, dissimilar price for the same service but with different levels of security considerations [12][13][14]. Hence, this article incorporates QoS attributes in the proposed model for web service selection. ...
... A prototype system was implemented supporting both OWL-S and goal-based queries. The goal reasoning algorithms proposed by Aiello and Giorgini [1] verify the satisfaction of non-functional requirements in i*goal models when specific SSs realize a required system functionality. While the first approach tries to connect the SS compositions produced to the goals that may satisfy, it does not consider the non-functional service aspect. ...
As organizations operate under a highly dynamic business world, they can only survive by optimizing their business processes (BPs) and outsourcing complementary functionality to their core business. To this end, they adopt service-orientation as the underlying mechanism enabling BP optimization and evolution. BPs are now seen as business services (BSs) that span organization boundaries and ought to satisfy cross-organizational objectives. As such, various BS design approaches have been proposed. However, these approaches cannot re-use existing business and software services (SSs) to realize the required BS functionality. Moreover, non-functional requirements and their impact on BS design are not considered. This research gap is covered by a novel, goal-oriented method able to discover those BS and SS compositions fulfilling the required BS functional and non-functional goals at both the business and IT level. This method coherently integrates the design steps involved and properly handles the lack of required BS components. It also advances the state-of-the-art in service composition by being able to both select the best composition plan and the best services realizing the plan tasks based on novel plan and service selection criteria.
... Agent-oriented solution. There is a proposal in [24] to use the agent-oriented methodology Tropos to model a web services properties. To provide modelling of a quality composition, the interacting services are represented as a multi-agent system. ...
Changeable requirements for modern services, provided in global environment, and their constant reengineering demand dynamic composition of services which is able to estimate changes of various parameters, both functional and non-functional ones. Web Services Agreement is a convenient way to contain QoS parameters, but state-of-the-art SLA-aware methods are not able to support all classes of nonfunctional parameters and provide runtime support and dynamic reconfiguration at the same time. This paper provides a novel SLA-aware dynamic Web Services Composition Approach that allows performing such composition.
... Quality of service (QoS) in service-oriented enterprise information systems is key factor for a number of reasons (Aiello, Giorgini, 2004): 1) autonomous services depend on one another; 2) services can compete one another -a service consumer's decision on a service may be based on its QoS properties; 3) a service provider can offer the same functionality but different qualities, and different qualities of the same service should be declared. However, common consensus on QoS in general is not achieved, as well as on QoS concept in service-oriented enterprises. ...
... For example, the view inherited from computer network community considers QoS in terms of performance and availability of service only. Some researchers assume that any custom characteristic that can be modelled as non-functional service requirement may be considered as a constituent of quality of service (Aiello, Giorgini, 2004). In addition, there are different understandings of the nature of quality in general and different points of view on software quality. ...
Paslaugų stiliaus architektūra tampa vyraujančia saityno paslaugomis grindžiamų sistemų kūrimo paradigma. Šiame straipsnyje pateikiama trijų dominuojančių paslaugų kokybės modeliavimo būdų: SQuaRE grindžiamo saityno paslaugų kokybės modelio, OASIS sudaryto saityno paslaugų kokybės modelio ir ontologija grindžiamo paslaugų kokybės modeliavimo būdo, pasiūlyto Beanchini su bendraautoriais, kritinė analizė. Pagrindinis darbo rezultatas yra straipsnyje parodomi analizuojamų būdų koncepciniai panašumai ir skirtumai, nagrinėjami trūkumai ir priežastys, neleidžiančios juos taikant adekvačiai modeliuoti paslaugų kokybės paslaugų stiliaus architektūros įmonių sistemose. Taip pat pateikiami argumentai, kad reikia sukurti naują, holistinį, paslaugų kokybės modeliavimo būdą.
Critical analysis and elaboration of three prevailing approaches to model quality of service
Audronė Lupeikienė, Jolanta Miliauskaitė, Albertas Čaplinskas
Summary
The service-oriented architecture (SOA) becomes dominant paradigm in the development of webbased systems. The paper critically analyses three prevailing approaches to SOA quality of service (QoS) modelling, namely, SQuaRE based Web Services Quality Model, OASIS Quality Model for Web Services and an ontology based QoS modelling approach proposed by Beanchini and co-authors. The main contribution of this paper is that it highlights both conceptual similarities and differences of the analysed approaches, examines their shortcomings and the reasons for their inability to model QoS adequately in service-oriented enterprise systems context. It also gives arguments for the need to develop a new, holistic QoS modelling approach.
... In the context of Web services, considerations of nonfunctional properties are critical for a number of reasons: firstly, autonomous services depend on one another for their functioning and they need to be aware of each other"s Quality of Service (QoS); secondly, a service requester may decide on the use of a particular servicedepending on its non-functional properties. Similarly, a service provider may offer the same function with a different QoS, for example, different prices for the same service but with different levels of security considerations (Aiello and Giorgini, 2004;Mani and Nagarajan, 2002). ...
... The probability that the service is up and running. Qian et al.(2008), Oldham et al.(2006), Maximilien and Singh (2004), Saleh et al. (2003) It is the average time to restore a service after a failure. ...
... The definitions, as proposed by Qian et al. (2008); Oldham et al. (2006);Maximilien and Singh (2004) and Saleh et al. (2003) imply that if a service is not in a "failed" state (i.e. not in the Crashed state), then it is "available". ...
... The QoS plays then an important role in the software service for different reasons (O'Sullivan et al., 2002;Aiello & Giorgini, 2004): (1) a service provider may offer the same functionality with differentiated QoS (for example different prices) and must therefore publish the different qualities for this same functionality; (2) a service requester may decide for a particular service based on its QoS properties; and (3) a service may depend on other services and it needs to be aware of the QoS of the collaborating services. Therefore, QoS becomes a main concern for providers and customers of a service. ...
... Several works in the literature (Zeng et al., 2003;Herssens et al., 2008;Aiello & Giorgini, 2004;Penserini & Mylopoulos, 2005;Ma et al., 2009) propose QoS models. Certain authors (Zeng et al., 2003;Herssens et al., 2008) consider the QoS as a collection of metrics related to non functional properties of services. ...
... Zeng et al. (2003) proposes a QoS model to describe concepts of QoS such as execution price and execution duration, whereas Herssens et al. (2008) recommend using the Unified Modeling Language (UML) to enable QoS modeling. Requirement engineering community (Aiello & Giorgini, 2004;Penserini & Mylopoulos, 2005;Ma et al., 2009) propose to reason about non functional requirements, based on the qualitative framework (Mylopoulos et al., 1992), by considering the QoS as soft goal that a service can satisficed. ...
The success of service-based applications is based on service technologies such as Web services. Nevertheless, the benefits of the Service-Oriented Architecture (SOA) remain mainly at the software level, since business people are often unable to fully exploit its benefits due to their unfamiliarity with such software level technology. The intentional Service-Oriented Architecture (iSOA) suggests a move from the function-driven SOA to intention-driven SOA in order to provide service description understandable by business practitioners. However, such transposition from business to implementation level should also consider Quality of Service (QoS) aspects. In this paper, we propose modeling the Quality of intentional Service (QoiS) by introducing the quality goals and their qualitative and quantitative evaluation. We also propose populating the intentional service registry of the iSOA architecture with the QoiS description.
... A prototype system was implemented supporting both semantic service queries and intentional queries concerning the goal to be achieved. Qualitative and quantitative goal reasoning algorithms are proposed in [10] which can verify if non-functional requirements described in terms of i*-goal models are satisfied when particular SSs are used to realize a required system's functionality. ...
As business process optimization and innovation are the only means to survive in such a dynamic business world, organizations are now combining BPM technologies with service-orientation so as to achieve them. Business processes are now considered as business services (BSs) that span the organizational boundaries and have to satisfy cross-organizational objectives. The most promising research approaches on BS design are not only considering what the BS does and how but also the business requirements that it must satisfy. They are also able to perform BS composition. However, they mainly concentrate on the functional aspect. Even if few of them do consider the non-functional aspect, they cannot select the best BS combination alternative in a precise and objective way. To this end, this paper proposes a goal-oriented approach that is able to discover the best possible way a BS can be composed from other BSs according to both functional and non-functional requirements. This approach advances the state-of-the-art in service composition and selection as it is able to propose semantically robust BS combinations even if there is a missing functionality in terms of partially fulfilled or unfulfilled required goals and considers novel optimization criteria such as the number of BSs constituting the proposed solution and the percentage of BSs reused.
