| This thesis focuses in the field of Software Architecture, a branch of Software Engineering which studies the structure of complex software systems. It deals specifically with one of the pending problems in it: the description of dynamic software architectures, those with a evolving structure. The study begins with a survey of the state-of-the-art, identifying the basic schemes in other proposals.; This thesis proposes to use Computational Reflection, the notion of self-dealing systems, as the unifying concept for those different proposals and basic schemes, leading to a more general approach to the description of dynamic architectures. Thus the main details of Reflection are examined, and the most relevant ones, in the context of Architecture, are selected. These are used to build an informal model of architectural description, capable to express the already known schemes of dynamism.; The reflective model is then formalized in three stages. Firstly, the usual concepts of Software Architecture are defined in terms of set and relation theory, giving them a proper formal framework. Secondly, this framework is extended by including the reflective concepts from the previous section. This provides a formal version for the above reflective model, in which an architecture is stratified in several description layers, termed meta-levels. Thirdly, a restricted version for this model is defined; this allows to express some of the most usual and relevant reflective structures more easily.; Then, using this model, a new Architectural Description Language named PiLar is designed. It is implicitly divided in two parts: a Structural Language, focusing in the static aspects of a description, and a Dynamic Language, used to specify the dynamic behaviour of an architecture. Both of them use a reification relationship as the only additional notion, and it proves to be enough to define a reflective scheme. Linguistically, the Structural Language is similar to any conventional ADL, while the Dynamic Language belongs to the family of “process algebraic” languages. Finally, the formal semantics for PiLar are defined, using the pi-calculus, a process algebra with mobility, as the foundation.; The thesis concludes showing the applicability of the language by describing a number of significant examples. |
