Specification and Verification of Context-dependent Services

Current approaches for the discovery, specification, and provision of services ignore the relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. We remedy this situation in this paper. We present a formal definition of services with context-dependent contracts. We define a composition theory of services with context-dependent contracts taking into consideration functional, nonfunctional, legal and contextual information. Finally, we present a formal verification approach that transforms the formal specification of service composition into extended timed automata that can be verified using the model checking tool UPPAAL.Comment: In Proceedings WWV 2011, arXiv:1108.208

Processo e evolução dos métodos formais na engenharia de requisitos

Requirements Engineering is considered the most important phase of the life cycle of software products because it specifies the needs of the customers, and it is also the basis for the execution of the other phases of software engineering. The models currently used to perform the requirements elicitation have been proposed and widely documented, but they are focused only on the techniques to collect information, disregarding the activity of properly documenting this information. Moreover, to structure the requirements specification, natural language continues to be used as a means of communication and understanding with the customer. Due to the ambiguities caused by this language, its interpretation becomes difficult, and this leads to reprocesses in the later stages of the software life cycle. According to the above, it is necessary for software development organizations to consider formalizing the process of requirements elicitation if they wish to make their development process more efficient. A literature review is carried out in this paper to determine the process and evolution of the formal methods from the requirements engineering perspective.La ingeniería de requisitos se considera la fase más importante del ciclo de vida de los productos de software, porque en ella se especifican las necesidades de los clientes y es la base para la ejecución de las demás fases de la ingeniería de software. Los modelos que actualmente se utilizan para realizar la elicitación de requisitos se han propuesto y documentado de forma amplia, pero se centran solo en las técnicas para colectar información y descuidan la actividad de documentarla de manera adecuada. Además, para estructurar la especificación de requisitos sigue en uso el lenguaje natural como forma de comunicación y comprensión con el cliente. Debido a las ambigüedades que este causa, se dificulta la interpretación; esto conlleva reprocesos en las etapas posteriores del ciclo de vida del software. De acuerdo con ello, es necesario que las organizaciones desarrolladoras de software consideren formalizar el proceso de elicitación de requisitos si desean hacer más eficiente su proceso de desarrollo. En este artículo se hace una revisión de literatura para determinar el proceso y evolución de los métodos formales desde la perspectiva de la ingeniería de requisitos. De acuerdo a lo anterior, es necesario que las organizaciones que desarrollan software consideren formalizar el proceso de elicitación de requisitos si desean hacer más eficiente su proceso de desarrollo. En este artículo se hace una revisión de literatura para determinar el proceso y evolución de los métodos formales desde la perspectiva de la Ingeniería de Requisitos. A engenharia de requisitos é considerada a fase mais importante do ciclo de vida dos produtos de software, porque nela se especificam as necessidades dos clientes e é a base para a execução das demais fases da engenharia de software. Os modelos que atualmente são utilizados para realizar a elicitação de requisitos foram propostos e documentados de forma ampla, mas se centram só nas técnicas para coletar informação e descuidam a atividade de documentar de maneira adequada. Além disso, para estruturar a especificação de requisitos segue em uso a linguagem natural como forma de comunicação e entendimento com o cliente. Devido às ambiguidades que este causa, dificulta-se a interpretação; isso implica reprocessos nas etapas posteriores do ciclo de vida do software. De acordo com isso, é necessário que as organizações desenvolvedoras de software considerem formalizar o processo de elicitação de requisitos se desejam tornar mais eficiente seu processo de desenvolvimento. Neste artigo, faz-se uma revisão de literatura para determinar o processo e a evolução dos métodos formais a partir da perspectiva da engenharia de requisitos

Context Aware Web-Service Monitoring

Monitoring the correct behaviour of a service-based system is a necessity and a key challenge in Service Oriented Computing. Several efforts have been directed towards the development of approaches dealing with the monitoring activity of service-based systems. However, these approaches are in general not suitable when dealing with modifications in service-based systems. Furthermore, existing monitoring approaches do not take into consideration the context of the users and how this context may affect the monitor activity. Consequently, a holistic monitor approach, capable of dealing with the dynamic nature of service-based systems and of taking into consideration the user context, would be highly desirable. In this thesis we present a monitor adaptation framework capable of dealing with changes in a service-based system and different types of users interacting with it. More specifically, the framework obtains a set of monitor rules, necessary to verify the correct behaviour of a service-based system, for a particular user. Moreover, the monitor rules verifying the behaviour of a service-based system relate to properties of the context types defined for a user. The main contributions of our work include the general characterisation of a user interacting with a service-based system and the generation of suitable monitor rules.The proposed framework can be applied to any service composition without the need of further modifications. Our work complements previous research carried on in the area of web service monitoring. More specifically, our work generates a set of suitable monitor rules - related to the user context - which are deployed in a run-time monitor component. Our framework has been tested and validated in several cases considering different scenarios