FlexMonitorWS : a solution for monitoring Web services with a focus on QoS attributes

Orientador: Cecília Mary Fischer RubiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Serviços Web são usados como uma das formas de se obter uma Arquitetura Orientada a Serviços (SOA). Com aspectos interoperáveis, dinâmicos e distribuídos, tais serviços agregam valores de negócio, são unidades de software com alta coesão e são utilizados para integração entre aplicações empresariais. Em um contexto de SOA, provedores de serviços devem oferecer garantias de funcionamento de seus serviços. Esta garantia é realizada através de atributos de Quality of Service (QoS) inseridos em contratos do tipo SLA (Service Level Agreement). Atributos de QoS podem ter flutuações ou mudança de estado ao longo do tempo, dado que um serviço opera em um ambiente de alta dinamicidade e alta imprevisibilidade que são propriedades inerentes ao contexto SOA. Diante deste cenário, há uma clara necessidade de se conhecer as variações que ocorrem nos atributos de QoS. Para isso, é fundamental aplicar uma monitoração que possibilite conhecer os valores de atributos de QoS para compreender o contexto geral do ambiente que opera o serviço. Uma boa solução de monitoração deve oferecer meios flexíveis de monitorar diferentes atributos de QoS (e.g. disponibilidade, desempenho e confiabilidade), de diferentes modos de operar, considerando diferentes alvos ligados ao serviço (e.g. servidor, rede e aplicação servidora). Por meio de uma Revisão Sistemática da Literatura identificamos que as soluções encontradas não apoiam a flexibilidade na monitoração. Face a este contexto, esta dissertação propôs a FlexMonitorWS uma solução de monitoração de serviços Web e de recursos de infraestrutura de TI ligada ao serviço Web. A FlexMonitorWS adota técnicas de Linhas de Produtos de Software para criar uma família de monitores a partir da variabilidade de software existente em sistemas de monitoração de serviços Web. Três estudos de caso foram executados para avaliar a viabilidade da ferramenta, obtendo-se resultados satisfatórios na entrega de valores de atributos de QoS e na compreensão do ambiente que opera o serviço Web. Ao final, apresentamos conclusões, contribuições e direções para trabalhos futurosAbstract: Web services are used as a way of obtaining a Service Oriented Architecture (SOA). With interoperable, dynamic and distributed aspects such services add business values are software units with high cohesion and are used to integrate business applications. In a SOA context, service providers must offer guarantees of the servces operations. This warranty is carried out by attributes Quality of Service (QoS) type contracts entered into SLA (Service Level Agreement). QoS attributes can have fluctuations or changes of state over time, given that a service operates in an environment of high dynamics and high unpredictability inherent in the SOA context properties. Given this scenario, there is a clear need to understand the fluctuations in the QoS attributes. Therefore, it is essential to apply a monitoring which allows to know the QoS attributes values to understand the overall context of the environment that operates the service. A good monitoring solution must offer flexible ways to monitor different QoS attributes (e.g. performance, availability and reliability) in different ways to operate, considering different targets linked to the service (e.g. server, network and server application). By analyzing existing solutions through a Systematic Literature Review identified that solutions do not support the flexibility in monitoring. Against this background, this thesis proposed a solution FlexMonitorWS monitoring of Web services and IT infrastructure resources connected to the Web services. FlexMonitorWS adopts techniques from Software Product Lines to create a monitors family from the existing variability in the Web services monitoring systems. Three case studies were performed to assess the tool feasibility, obtaining satisfactory results in delivering QoS attributes values and understanding to environment that operates the Web service. In the end, conclusions, contributions and directions for future work are presentedMestradoCiência da ComputaçãoMestre em Ciência da Computaçã

A Reinforcement Learning Quality of Service Negotiation Framework For IoT Middleware

The Internet of Things (IoT) ecosystem is characterised by heterogeneous devices dynamically interacting with each other to perform a specific task, often without human intervention. This interaction typically occurs in a service-oriented manner and is facilitated by an IoT middleware. The service provision paradigm enables the functionalities of IoT devices to be provided as IoT services to perform actuation tasks in critical-safety systems such as autonomous, connected vehicle system and industrial control systems. As IoT systems are increasingly deployed into an environment characterised by continuous changes and uncertainties, there have been growing concerns on how to resolve the Quality of Service (QoS) contentions between heterogeneous devices with conflicting preferences to guarantee the execution of mission-critical actuation tasks. With IoT devices with different QoS constraints as IoT service providers spontaneously interacts with IoT service consumers with varied QoS requirements, it becomes essential to find the best way to establish and manage the QoS agreement in the middleware as a compromise in the QoS could lead to negative consequences. This thesis presents a QoS negotiation framework, IoTQoSystem, for IoT service-oriented middleware. The QoS framework is underpinned by a negotiation process that is modelled as a Markov Decision Process (MDP). A model-based Reinforcement Learning negotiation strategy is proposed for generating an acceptable QoS solution in a dynamic, multilateral and multi-parameter scenarios. A microservice-oriented negotiation architecture is developed that combines negotiation, monitoring and forecasting to provide a self-managing mechanism for ensuring the successful execution of actuation tasks in an IoT environment. Using a case study, the developed QoS negotiation framework was evaluated using real-world data sets with different negotiation scenarios to illustrate its scalability, reliability and performance

Modeling and negotiating service quality

In this chapter the research problems of specifying and negotiating QoS and its corresponding quality documents are analyzed. For this reason, this chapter is separated into two main sections, Section 6.1 and 6.2, with each dedicated to one of the two problems, i.e., QoS specification and negotiation, respectively. Each section has a similar structure: they first introduce the problem and then, in the remaining subsections, review related work. Finally, the chapter ends with Section 6.3, which identifies research gaps and presents potential research challenges in QoS modelling, specification and negotiation

Modeling and negotiating service quality

In this chapter the research problems of specifying and negotiating QoS and its corresponding quality documents are analyzed. For this reason, this chapter is separated into two main sections, Section 6.1 and 6.2, with each dedicated to one of the two problems, i.e., QoS specification and negotiation, respectively. Each section has a similar structure: they first introduce the problem and then, in the remaining subsections, review related work. Finally, the chapter ends with Section 6.3, which identifies research gaps and presents potential research challenges in QoS modelling, specification and negotiation