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Change is an intrinsic property of software. A software system, during its lifetime, may require several updates, improvements, or new features. If these change requirements are not addressed, the risk of becoming a useless system increases. In fact, this is a challenging issue of safety-and mission-critical software systems, which cannot be stopped to perform maintenance or evolution operations due to their continuous operation. To reduce the aging of these critical systems, they must be provided with mechanisms enabling their dynamic evolution, i.e. the support of changes on their structure and behaviour while they remain in operation.This thesis is concerned with the design of a framework to build architecturebased, dynamically evolvable, software systems. The fact that this framework is a software architecture based approach provides the following advantages: (i) it offers a high-level of abstraction for describing dynamic changes; (ii) it allows varying the level of system description; and (iii) it advantages from the existing support for system modelling, code-generation, and formal analysis provided by architecture description languages.The framework presented in this thesis, called Dynamic PRISMA, is characterized by the combination of two levels of dynamism: Dynamic Reconfiguration, which addresses changes at the configuration level (i.e. the architectural configuration), and Dynamic Type Evolution, which addresses changes at the type-level (i.e. the specification of architectural types and instances). This combination is one of the major contributions of this thesis: thus a system is not only able to reconfigure at runtime the building blocks it is composed of (i.e. architectural types), but also to redefine these building blocks (or introduce new ones) at runtime.Another contribution of the thesis is the identification of the concerns related to dynamic evolution and their integration in the framework through aspects. This improves the separation of concerns and allows us to change reconfiguration specifications, evolution mechanisms, or the business logic independently of each other.A third contribution of this thesis is how this dynamism is supported: reconfiguration through autonomic capabilities, which provides proactivity according to either internal or external stimuli; and type evolution through asynchronous reflection, which enables the modification of a type specification and the transformation of their instances at different rates (i.e. when they are ready for evolution). Specifically, the asynchronous evolution vi semantics is precisely described by means of graph transformations. This formalism has been chosen because it naturally models both the system architecture and its asynchronous evolution.The work presented in this thesis is illustrated through a case study from the robotics domain; an area which could potentially benefit from the results of this thesis. KEYWORDSsoftware architectures, dynamic evolution, dynamic reconfiguration, dynamic type evolution, dynamic instance evol...

Abstract

The complexity and the big size of current software systems are challenges to be faced in software development. In the last few years, these challenges have increased the effort required to develop such large software systems. As a result, students must be able to develop these systems using approaches that reduce their development costs. Two of these approaches are Software Architectures and the Aspect-Oriented Software Development. However, in order to acquire skills in these approaches, students must put them into practice in realistic software projects. For this reason, we propose a reverse engineering method to learn these approaches by using open-source projects.

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As the number of existing software systems increases, it also does the number of software engineers involved in the maintenance of large existing systems. Maintenance projects are becoming more usual than new software developments. For this reason, Computer Science education should also consider the development of abilities to deal with large existing software systems. This paper describes an approach to teach software engineering by using existing real-life software systems, through reverse software engineering techniques. The approach introduces the student into a medium-sized team which has to perform a set of modifications over an unknown large software system. The learning process is directed towards the improvement of abstraction skills, a key skill for software engineers.