In the modern world, service oriented applications are becoming more and more popular from year to year. To remain competitive, these Web services must provide the high level of quality. From another perspective, the end user is interested in getting the service, which fits the user's requirements the best: for limited resources get the service with the best available quality. In this work, the model for automated service selection was presented to solve this problem. The main focus of this work was to provide high accuracy of this model during the prediction of Web service’s response time. Therefore, several machine learning algorithms were selected and used in the model as well as several experiments were conducted and their results were evaluated and analysed to select one machine learning algorithm, which coped best with the defined task. This machine learning algorithm was used in final version of the model. As a result, the selection model was implemented, whose accuracy was around 80% while selecting only one Web service as a best from the list of available. Moreover, one strategy for measuring accuracy has also been developed, the main idea of which is the following: not one but several Web services, the difference in the response time of which does not exceed the boundary value, can be considered as optimal ones. According to this strategy, the maximum accuracy of selecting the best Web service was about 89%. In addition, a strategy for selecting the best Web service from the end-user side was developed to evaluate the performance of implemented model. Finally, it should also be mentioned that with the help of specific tool the input data for the experiments was generated, which allowed not only generating different input datasets without huge time consumption but also using the input data with the different type (linear, periodic) for experiments.

Problem There is a lack of knowledge about how Swedish SMEs make decisions on IT service selection. There is also lack of information about the attributes of IT service providers that are most important to Swedish SMEs. By discovering these attributes, IT service providers could focus on improving their services in those dimensions and become more attractive for Swedish small and medium enterprises. Purpose The purpose of this research is to investigate the decision making process over selection of IT services for small and medium sized enterprises (SMEs) in Sweden. Additionally, this research intends to discover the most important features (attributes) of an IT service provider in its selection. What are the steps involved in decision-making process? What decision-making methods can be used to help explain the process that goes on in the minds of the decision makers? What aspects influence their behaviour when decision makers prefer one service provider to another? IT service comprises of internet-based services such as web hosting, email services, online backup services and cloud apps or locally offered IT services such as IT helpdesk. The candidates who were interviewed were employees or entrepreneurs who work and live in Sweden. Method This research was conducted with an inductive approach using mono method for semi-structured interviews for primary data collection. Secondary data collection was multiple-source through literature reviews in order to learn about different attributes and current knowledge about this subject. The research method was qualitative with exploratory strategy in order to get insights into managers’ decision-making processes. Sampling was non-probability purposive method with sample size as saturation method. The focus was illustrative and method chosen as typical case. Conclusion The conclusions of this thesis illustrates that the important attributes (features) of IT services required by Swedish SMEs are the requirement that the service is being offered from Sweden, due to tax conformity laws and security matters. Moreover, SAT, WADD, FRQ and EBA are decision-making heuristics in use by the companies in selection of suitable IT services.

Un service Web est un moyen d'offrir des fonctionnalités sur un réseau en utilisant des normes ouvertes pour la description et l'invocation. Les services Web représentent une réalisation importante de l'Architecture Orientée Service (AOS), à l'aide de qui, les applications peuvent être développées rapidement avec un coût bas par couplage faible les services sur un réseau. Cela nécessite la découverte et la composition des ensembles de services interopérables, selon certaines exigences fonctionnelles et non fonctionnelles. Les services Web confrontent de nombreux défis quant à leur découverte et sélection, en raison de plusieurs facteurs tels que: le nombre important de services, le manque de registres publics capables d'offrir des mécanismes efficaces de récupération de service, de leur nature dynamique qui impose divers aspects de QoS tels que la disponibilité, le temps de réponse, etc, et le manque de sémantique dans leurs descriptions d'interface. Dans cette thèse, nous avons deux objectifs principaux. Notre premier objectif est de faciliter la sélection des services Web et d'assurer la continuité du service dans des compositions de services Web. Par conséquent, nous proposons une approche basée sur l'analyse formelle de concepts (AFC) pour classer les services Web dans un premier temps par mots clés, puis par les valeurs de similarité entre leurs opérations. Cette classification est représentée comme un treillis de concepts qui révèle les relations entre les services, ce qui facilite la sélection d'un service nécessaire ainsi que l'identification des potentiels sauvegardes (substitutions en cas de panne). Notre deuxième objectif est de guider l'utilisateur en effectuant une sélection optimisée basée sur des plusieurs critères. Nous définissons un descripteur pour l'utilisateur qui spécifie des exigences fonctionnelles et non fonctionnelles. Dans ce descripteur, les propriétés fonctionnelles sont spécifiées comme un ensemble de mots-clés. Les propriétés non fonctionnelles représentent les niveaux attendus de QoS (bon, mauvais, moyen, ..) ainsi que la composition de services exprimée en tant que liens entre les propriétés fonctionnelles spécifiées. Afin d'atteindre cet objectif, nous proposons une approche basée sur l'analyse relationnelle de concepts (ARC) qui classifie les services Web en treillis de concepts similaires à la AFC, mais enrichis avec les propriétés non-fonctionnelles. Nous proposons également un mécanisme permettant d'interroger le concept de treillis résultant basée sur RCA, selon les exigences spécifiées dans le descripteur. Nous avons validé notre proposition en utilisant des services Web réels extraits de Service-Finder et Seekda (des moteurs de recherche de services Web). Pour l'approche basée sur la AFC, nous avons récupéré un total de 145 services Web que nous avons classés en fonction de leur fonctionnalité. Nous avons montré comment sélectionner efficacement un service offrant les fonctionnalités requises et la manière d'identifier ses sauvegardes. Pour l'approche basée sur RCA, nous avons récupéré 901 services Web que nous avons classés selon leur niveau de QoS et de composabilité. Nous avons vérifié que cette approche permet une sélection efficace des services correspondant aux exigences fonctionnelles et non fonctionnelles spécifiées. / A Web service is a way of offering functionality over a network using open standards for description and invocation. Web services represent an important realization of Service-Oriented Architectures (SOA), using which, applications can be developed rapidly with a low cost by loosely coupling services over a network. This necessitates discovering and composing sets of interoperable services, according to some functional and non-functional requirements.Web services face many challenges regarding their discovery and selection, due to several factors like: the fairly large number of services, the lack of public registries capable of offering efficient service retrieval mechanisms, their dynamic nature which imposes various QoS aspects such as availability, response time, etc., and the lack of semantics in their interface descriptions.In this thesis, we have two main objectives. Our first objective is to facilitate Web service selection and assure service continuity in Web service compositions. Therefore, we propose an approach based on Formal Concept Analysis (FCA) to classify Web services first by keywords then by similarity values between their operations. This classification is represented as a concept lattice that reveals the relations between the services, which facilitates the selection of a needed service as well as the identification of its potential backups (substitution in case of failure).Our second objective is to guide the user towards performing an optimized multi-criteria based selection. We define a user requirements descriptor that specifies the needed functional and non-functional properties. Inside this descriptor, functional properties are specified as a set of keywords. Non-functional properties represent the expected QoS levels (good, bad, medium, ..) as well as the composition of services expressed as links between the specified functional properties. In order to meet this objective, we propose an approach based on Relational Concept Analysis (RCA) that classifies Web services into concept lattices similar to FCA, but enriched with the non-functional properties. We also propose a mechanism to query the resulting RCA-based concept lattices, according to the requirements specified in the descriptor.We validated our proposition using real Web services retrieved from Service-Finder and Seekda Web service search engines. For the FCA-based approach, we retrieved a total of 145 Web services that we classified by their functionality. We showed how to select efficiently a service offering the required functionality and how to identify its backups.For the RCA-based approach, we retrieved 901 Web services that we classified by their QoS and composability levels. We verified that the approach allows an efficient selection of services corresponding to the specified functional and non-functional requirements.

Workflow systems orchestrate various business tasks to attain an objective. Web services can be leveraged to handle individual tasks. Before anyone intends to leverage service components, it is imperative and essential to evaluate the trustworthiness of these services. Therefore, choosing a trustworthy service has become an important decision while designing a workflow system. Trustworthiness can be defined as the likelihood of a service functioning as it is intended. Selection of a service that satisfies business goals involves collecting relevant information such as security mechanisms, reliability, performance and availability. It is important to arrive at total trustworthiness, which incorporates all of the above mentioned multi-facet values relevant to a service. These values can be gathered and analyzed to derive the total trustworthiness of a service. Measuring trustworthiness of a service involves arriving at a suitable value that would help an end-user make a decision for the given business settings. The primary focus of this thesis is to gather relevant details and measure trustworthiness based on inputs provided by the user. A conceptual model was developed after extensive literature review to identify factors that influence trustworthiness of a service. A mechanism was created to gather concept values for a given service and utilize those values to calculate trustworthiness index value. A proof-of-concept prototype was also developed. The prototype is a web-based application that implements the mechanism to measure the trustworthiness of the service. The prototype was evaluated using a scenario-based analysis method to demonstrate the utility of the trustworthiness mechanism using three different scenarios. Results of the evaluation shows that trustworthiness is a multidimensional concept, the relevant conceptual values can be collected, a trustworthiness index value can be calculated based on the gathered concepts, and a trustworthiness index can be interpreted to select the most relevant service for a given requirement.

No description available.

Home and community based services (HCBS) are designed to provide services that meet the increasing and diverse needs of the older adult population who wish to age-in-place for as long as possible in their homes and community. Yet, little is known about the choices people make when selecting services. The purpose of this study was to assess HCBS use among vulnerable older adults. Andersen’s (1995) behavioral model of health services use provided theoretical guidance for selecting and explaining predisposing, enabling, and need-based variables associated with service use within the Community Living Program (CLP) federal initiative. Through consumer direction of services, 18 routine or one-time services were offered to 76 participants enrolled in the Virginia CLP. Two-step cluster analysis identified four distinct profiles of service users, ranging in size from 7 to 34 members. Services used within the groups ranged from 11 to 16 services. Use of personal care services (p=.033) and respite (p=.010) were significantly associated with group membership differentiation. Within each cluster, the percentage of participants using each service varied greatly. The most important variables that differentiated service user membership were caregiver relationship to participant, participant living arrangement, participant disability type, and length of time caregiver provided care. Between-cluster membership was significantly different with regard to average service cost per day for services used (p=.002) and the likelihood of moving to a nursing home if services were not provided (p=.034). Findings inform future research and have implications for practitioners assisting vulnerable older adults in selecting services to meet different care needs. / Master of Science

De nos jours, nous assistons à l’émigration du Web de données vers le Web orienté services. L’amélioration des capacités et fonctionnalités des moteurs actuels de recherche sur le Web, par des techniques efficaces de recherche et de sélection de services, devient de plus en plus importante. Dans cette thèse, dans un premier temps, nous proposons un cadre de composition de services Web en tenant compte des préférences utilisateurs. Le modèle fondé sur la théorie des ensembles flous est utilisé pour représenter les préférences. L’approche proposée est basée sur une version étendue du principe d’optimalité de Pareto. Ainsi, la notion des top-k compositions est introduite pour répondre à des requêtes utilisateurs de nature complexe. Afin d’améliorer la qualité de l’ensemble des compositions retournées, un second filtre est appliqué à cet ensemble en utilisant le critère de diversité. Dans un second temps, nous avons considéré le problème de la sélection des services Web en présence de préférences émanant de plusieurs utilisateurs. Une nouvelle variante, appelée Skyline de services à majorité, du Skyline de services traditionnel est défini. Ce qui permet aux utilisateurs de prendre une décision « démocratique » conduisant aux services les plus appropriés. Un autre type de Skyline de services est également discuté dans cette thèse. Il s’agit d’un Skyline de Services de nature graduelle et se fonde sur une relation de dominance floue. Comme résultat, les services Web présentant un meilleur compromis entre les paramètres QoS sont retenus, alors que les services Web ayant un mauvais compromis entre les QoS sont exclus. Finalement, nous avons aussi absorbé le cas où les QoS décrivant les services Web sont entachés d’incertitude. La théorie des possibilités est utilisée comme modèle de l’incertain. Ainsi, un Skyline de Services possibilité est proposé pour permettre à l’utilisateur de sélectionner les services Web désirés en présence de QoS incertains. De riches expérimentations ont été conduites afin d’évaluer et de valider toutes les approches proposées dans cette thèse / As we move from a Web of data to a Web of services, enhancing the capabilities of the current Web search engines with effective and efficient techniques for Web services retrieval and selection becomes an important issue. In this dissertation, we present a framework that identifies the top-k Web service compositions according to the user fuzzy preferences based on a fuzzification of the Pareto dominance relationship. We also provide a method to improve the diversity of the top-k compositions. An efficient algorithm is proposed for each method. We evaluate our approach through a set of thorough experiments. After that, we consider the problem of Web service selection under multiple users preferences. We introduce a novel concept called majority service skyline for this problem based on the majority rule. This allows users to make a “democratic” decision on which Web services are the most appropriate. We develop a suitable algorithm for computing the majority service skyline. We conduct a set of thorough experiments to evaluate the effectiveness of the majority service skyline and the efficiency of our algorithm. We then propose the notion of α-dominant service skyline based on a fuzzification of Pareto dominance relationship, which allows the inclusion of Web services with a good compromise between QoS parameters, and the exclusion ofWeb services with a bad compromise between QoS parameters. We develop an efficient algorithm based on R-Tree index structure for computing efficiently the α-dominant service skyline. We evaluate the effectiveness of the α-dominant service skyline and the efficiency of the algorithm through a set of experiments. Finally, we consider the uncertainty of the QoS delivered by Web services. We model each uncertain QoS attribute using a possibility distribution, and we introduce the notion of pos-dominant service skyline and the notion of nec-dominant service skyline that facilitates users to select their desired Web services with the presence of uncertainty in their QoS. We then developappropriate algorithms to efficiently compute both the pos-dominant service skyline and nec-dominant service skyline. We conduct extensive sets of experiments to evaluate the proposed service skyline extensions and algorithms

In service-oriented environments, services are put together in the form of a workflow with the aim of distributed problem solving. Capturing the execution details of the services' transformations is a significant advantage of using workflows. These execution details, referred to as provenance information, are usually traced automatically and stored in provenance stores. Provenance data contains the data recorded by a workflow engine during a workflow execution. It identifies what data is passed between services, which services are involved, and how results are eventually generated for particular sets of input values. Provenance information is of great importance and has found its way through areas in computer science such as: Bioinformatics, database, social, sensor networks, etc. Current exploitation and application of provenance data is very limited as provenance systems started being developed for specific applications. Thus, applying learning and knowledge discovery methods to provenance data can provide rich and useful information on workflows and services. Therefore, in this work, the challenges with workflows and services are studied to discover the possibilities and benefits of providing solutions by using provenance data. A multifunctional architecture is presented which addresses the workflow and service issues by exploiting provenance data. These challenges include workflow composition, abstract workflow selection, refinement, evaluation, and graph model extraction. The specific contribution of the proposed architecture is its novelty in providing a basis for taking advantage of the previous execution details of services and workflows along with artificial intelligence and knowledge management techniques to resolve the major challenges regarding workflows. The presented architecture is application-independent and could be deployed in any area. The requirements for such an architecture along with its building components are discussed. Furthermore, the responsibility of the components, related works and the implementation details of the architecture along with each component are presented.

La robotique ambiante s'intéresse à l'introduction de robots mobiles au sein d'environnements actifs où ces derniers fournissent des fonctionnalités alternatives ou complémentaires à celles embarquées par les robots mobiles. Cette thèse étudie la mise en concurrence des fonctionnalités internes et externes aux robots, qu'elle pose comme un problème de sélection de services logiciels. La sélection de services consiste à choisir un service ou une combinaison de services parmi un ensemble de candidats capables de réaliser une tâche requise. Pour cela, elle doit prédire et évaluer la performance des candidats. Ces performances reposent sur des critères non-fonctionnels comme la durée d'exécution, le coût ou le bruit. Ce domaine applicatif a pour particularité de nécessiter une coordination étroite entre certaines de ses fonctionnalités. Cette coordination se traduit par l'échange de flots de données entre les fonctionnalités durant leurs exécutions. Les fonctionnalités productrices de ces flots sont modélisées comme des services continus. Cette nouvelle catégorie de services logiciels impose que les compositions de services soient hiérarchiques et introduit des contraintes supplémentaires pour la sélection de services. Cette thèse met en évidence la présence d'un important couplage non-fonctionnel entre les performances des instances de services de différents niveaux, même lorsque les flots de données sont unidirectionnels. L'approche proposée se concentre sur la prédiction de la performance d'une instance de haut-niveau sachant son organigramme à l'issue de la sélection. Un organigramme regroupe l'ensemble des instances de services sollicitées pour réaliser une tâche de haut-niveau. L'étude s'appuie sur un scénario impliquant la sélection d'un service de positionnement en vue de permettre le déplacement d'un robot vers une destination requise. Pour un organigramme considéré, la prédiction de performance d'une instance de haut-niveau de ce scénario introduit les exigences suivantes : elle doit (i)être contextuelle en tenant compte, par exemple, du chemin suivi pour atteindre la destination requise, (ii) prendre en charge le remplacement d'une instance de sous-service suite à un échec ou, par extension, de façon opportuniste. En conséquence, cette sélection de services est posée comme un problème de prise de décision séquentielle formalisé à l'aide de processus de décision markoviens à horizon fini. La dimensionnalité importante du contexte en comparaison à la fréquence des déplacements du robot rend inadaptées les méthodes consistant à apprendre directement une fonction de valeur ou une fonction de transition. L'approche proposée repose sur des modèles de dynamique locaux et exploite le chemin de déplacement calculé par un sous-service pour estimer en ligne les valeurs des organigrammes disponibles dans l'état courant. Cette estimation est effectuée par l'intermédiaire d'une méthode de fouille stochastique d'arbre, Upper Confidence bounds applied to Trees / Ambient robotics aims at introducing mobile robots in active environments where the latter provide new or alternative functionalities to those shipped by mobile robots. This thesis studies the competition between robot and external functionalities, which is set as a service selection problem. Service selection consists in choosing a service or a combination of services among a set of candidates able to fulfil a given request. To do this, it has to predict and evaluate candidate performances. These performances are based on non-functional requirements such as execution time, cost or noise. This application domain requires tight coordination between some of its functionalities. Tight coordination involves setting data streams between functionalities during their execution. In this proposal, functionalities producing data streams are modelled as continuous services. This new service category requires hierarchical service composition and adds some constraints to the service selection problem. This thesis shows that an important non-functional coupling appears between service instances at different levels, even when data streams are unidirectional. The proposed approach focuses on performance prediction of an high-level service instance given its organigram. This organigram gathers service instances involved in the high-level task processing. The scenario included in this study is the selection of a positioning service involved in a robot navigation high-level service. For a given organigram, performance prediction of an high-level service instance of this scenario has to: (i) be contextual by, for instance, considering moving path towards the required destination, (ii) support service instance replacement after a failure or in an opportunist manner. Consequently, this service selection is set as a sequential decision problem and is formalized as a finite-horizon Markov decision process. Its high contextual dimensionality with respect to robot moving frequency makes direct learning of Q-value functions or transition functions inadequate. The proposed approachre lies on local dynamic models and uses the planned moving path to estimate Q-values of organigrams available in the initial state. This estimation is done using a Monte-Carlo tree search method, Upper Confidence bounds applied to Trees

Seleção de serviços em composições distribuídas considera principalmente a qualidade de serviço que atenda requisitos estabelecidos pelo usuário, como por exemplo, preço. No entanto, problemas relacionados a execução de composições de serviços podem ocorrer quando não se considera aspectos relacionados à rede e ao hardware, que afetam diretamente o desempenho da composição. Esse problema se agrava em composições coreografadas, pois a característica descentralizada requer um maior esforço para que essas informações possam ser consideradas em uma perspectiva global. Dessa forma, apesar da descentralização apresentar vantagens, é necessário que requisitos de qualidade de serviço da composição também sejam considerados em coreografias de serviços web para que a escolha de serviços para desempenhar um papel leve em consideração parâmetros importantes que podem afetar no desempenho da composição. Este trabalho apresenta um mecanismo, implementado sobre o framework OpenKnowledge, para selecionar serviços web em ambientes coreografados considerando primeiramente estimativas de atraso, taxa de perda e por fim considera a utilização de outros parâmetros, como utilização de CPU. Os primeiros experimentos em diferentes cenários de rede confirmaram as vantagens da proposta em relação a um seletor de serviços que ignora aspectos relacionados com a rede. Obteve-se ganhos de 20 a 97% no que diz respeito ao tempo total da execução da coreografia. Em seguida, experimentos inserindo utilização de CPU na escolha dos serviços confirmaram as vantagens de utilização de diferentes parâmetros para seleção de serviços em coreografias. / Selection of services in distributed compositions mainly considers the quality of service that meets requirements set by the user, such as price. However, problems related to the execution of service compositions may occur when aspects related to network and hardware, which directly affect the performance of the composition, are not taken in consideration. This problem is aggravated in choreographed compositions because the decentralized feature requires a greater effort so that this information may be considered in a global perspective. Thus, despite the decentralization advantages, it is necessary that the service quality requirements of the composition may also be considered in the choreography of web services so that the choice of services may play a role that takes into account important parameters, which can affect the performance of the composition. This dissertation presents a mechanism, implemented on the OpenKnowledge framework, to select web services in choreographed environments. First, considering delay estimates, loss rate and finally the use of other parameters, such as CPU utilization. The first experiments on different network scenarios confirmed the proposal advantages in relation to a selection mechanism that bypasses aspects of the network. It was obtained gains from 20% to 97% considering the total time of execution of the choreography. Then, experiments inserting CPU utilization in the choice of services confirmed the advantages of using different parameters for selection of services in choreography.