Sistema de teste auto-adaptativo baseado em modelo para SOA dinâmico

Orientadores: Eliane Martins, Andrea CeccarelliDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Arquitetura orientada a serviços (SOA) é um padrão de design popular para implemen- tação de serviços web devido à interoperabilidade, escalabilidade e reuso de soluções de software que promove. Os serviços que usam essa arquitetura precisam operar em um am- biente altamente dinâmico, entretanto quanto mais a complexidade desses serviços cresce menos os métodos tradicionais de validação se mostram viáveis. Aplicações baseadas em arquitetura orientada a serviços podem evoluir e mudar du- rante a execução. Por conta disso testes offline não asseguram completamente o compor- tamento correto de um sistema em tempo de execução. Por essa razão, a necessidade de tecnicas diferentes para validar o comportamento adequado de uma aplicação SOA durante o seu ciclo de vida são necessárias, por isso testes online executados durante o funcionamento serão usados nesse projeto. O objetivo do projeto é de aplicar técnicas de testes baseados em modelos para gerar e executar casos de testes relevantes em aplicações SOA durante seu tempo de execu- ção. Para alcançar esse objetivo uma estrura de teste online autoadaptativa baseada em modelos foi idealizada. Testes baseados em modelos podem ser gerados de maneira offline ou online. Nos testes offline, os casos de teste são gerados antes do sistema entrar em execução. Já nos testes online, os casos de teste são gerados e aplicados concomitantemente, e as saídas produzidas pela aplicação em teste definem o próximo passo a ser realizado. Quando uma evolução é detectada em um serviço monitorado uma atualização no modelo da aplicação alvo é executada, seguido pela geração e execução de casos de testes online. Mais precisamente, quatro componentes foram integrados em um circuito autoadap- tativo: um serviço de monitoramento, um serviço de criação de modelos, um serviço de geração de casos de teste baseado em modelos e um serviço de teste. As caracteristicas da estrutura de teste foram testadas em três cenários que foram executados em uma aplicação SOA orquestrada por BPEL, chamada jSeduite. Este trabalho é um esforço para entender as restrições e limitações de teste de soft- ware para aplicações SOA, e apresenta análises e soluções para alguns dos problemas encontrados durante a pesquisaAbstract: Service Oriented Architecture (SOA) is a popular design pattern to build web services be- cause of the interoperability, scalability, and reuse of software solutions that it promotes. The services using this architecture need to operate in a highly dynamic environment, but as the complexity of these services grows, traditional validation processes become less feasible. SOA applications can evolve and change during their execution, and offline tests do not completely assure the correct behavior of the system during its execution. There- fore there is a need of techniques to validate the proper behaviour of SOA applications during the SOA lifecycle. Because of that, in this project online testing will be used. The project goal is to employ model-based testing techniques to generate and execute relevant test cases to SOA applications during runtime. In order to achieve this goal a self-adaptive model-based online testing framework was designed. Tests based on models can be generated offline and online. Offline test are generated before the system execution. Online tests are generated and performed concomitantly, and the output produced by the application under test defines the next step to be performed. when our solution detects that a monitored service evolves, the model of the target service is updated, and online test case generation and execution is performed. More specifically, four components were integrated in a self-adaptive loop: a mon- itoring service, a model generator service, a model based testing service and a testing platform. The testing framework had its features tested in three scenarios that were performed in a SOA application orchestrated by BPEL, called jSeduite. This work is an effort to understand the constraints and limitations of the software testing on SOA applications, and present analysis and solutions to some of the problems found during the researchMestradoCiência da ComputaçãoMestre em Ciência da ComputaçãoCAPE

A survey on engineering approaches for self-adaptive systems (extended version)

The complexity of information systems is increasing in recent years, leading to increased effort for maintenance and configuration. Self-adaptive systems (SASs) address this issue. Due to new computing trends, such as pervasive computing, miniaturization of IT leads to mobile devices with the emerging need for context adaptation. Therefore, it is beneficial that devices are able to adapt context. Hence, we propose to extend the definition of SASs and include context adaptation. This paper presents a taxonomy of self-adaptation and a survey on engineering SASs. Based on the taxonomy and the survey, we motivate a new perspective on SAS including context adaptation

QoS awareness and adaptation in service composition

The dynamic nature of a Web service execution environment generates frequent variations in the Quality of Service offered to the consumers, therefore, obtaining the expected results while running a composite service is not guaranteed. When combining this highly changing environment with the increasing emphasis on Quality of Service, management of composite services turns into a time consuming and complicated task. Different approaches and tools have been proposed to mitigate the impacts of unexpected events during the execution of composite services. Among them, self-adaptive proposals have stood out, since they aim to maintain functional and quality levels, by dynamically adapting composite services to the environment conditions, reducing human intervention. The research presented in this Thesis is centred on self-adaptive properties in service composition, mainly focused on self-optimization. Three models have been proposed to target self-optimization, considering various QoS parameters, the benefit of performing adaptation, and looking at adaptation from two perspectives: reactive and proactive. They target situations where the QoS of the composition is decreasing. Also, they consider situations where a number of the accumulated QoS values, in certain point of the process, are better than expected, providing the possibility of improving other QoS parameters. These approaches have been implemented in service composition frameworks and evaluated through the execution of test cases. Evaluation was performed by comparing the QoS values gathered from multiple executions of composite services, using the proposed optimization models and a non-adaptive approach. The benefit of adaptation was found a useful value during the decision making process, in order to determine if adaptation was needed or not. Results show that using optimization mechanisms when executing composite services provide significant improvements in the global QoS values of the compositions. Nevertheless, in some cases there is a trade-off, where one of the measured parameters shows an increment, in order to improve the others

Ensuring Service Level Agreements for Composite Services by Means of Request Scheduling

Building distributed systems according to the Service-Oriented Architecture (SOA) allows simplifying the integration process, reducing development costs and increasing scalability, interoperability and openness. SOA endorses the reusability of existing services and aggregating them into new service layers for future recycling. At the same time, the complexity of large service-oriented systems negatively reflects on their behavior in terms of the exhibited Quality of Service. To address this problem this thesis focuses on using request scheduling for meeting Service Level Agreements (SLAs). The special focus is given to composite services specified by means of workflow languages. The proposed solution suggests using two level scheduling: global and local. The global policies assign the response time requirements for component service invocations. The local scheduling policies are responsible for performing request scheduling in order to meet these requirements. The proposed scheduling approach can be deployed without altering the code of the scheduled services, does not require a central point of control and is platform independent. The experiments, conducted using a simulation, were used to study the effectiveness and the feasibility of the proposed scheduling schemes in respect to various deployment requirements. The validity of the simulation was confirmed by comparing its results to the results obtained in experiments with a real-world service. The proposed approach was shown to work well under different traffic conditions and with different types of SLAs

Engineering framework for service-oriented automation systems

Tese de doutoramento. Engenharia Informática. Universidade do Porto. Faculdade de Engenharia. 201

Coverage Based Testing for Service Level Agreements

Service level agreements (SLAs) are typically used to specify rules regarding the consumption of services that are agreed between the providers of the service-based applications (SBAs) and their consumers. An SLA includes a list of terms that contain the guarantees that must be fulfilled during the provisioning and consumption of the services. Since the violation of such guarantees may lead to the application of potential penalties, it is important to assure that the SBA behaves as expected. In this paper, we propose a proactive approach to test SLA-aware SBAs by means of identifying test requirements, which represent situations that are relevant to be tested. To address this issue, we define a four-valued logic that allows evaluating both the individual guarantee terms and their logical relationships. Grounded in this logic, we devise a test criterion based on the modified condition decision coverage (MCDC) in order to obtain a cost-effective set of test requirements from the structure of the SLA. Furthermore by analyzing the syntax and semantics of the agreement, we define specific rules to avoid non-feasible test requirements. The whole approach has been automated and applied over an eHealth case study