Cálculo de ambientes tipado sensível ao contexto para aplicações pervasivas

Abstract

Nowadays, mobile computing is more present in daily life. Mobile phones, notebooks, smart phones and wireless networks are part of everyday life. With this technology available, the research in pervasive computing is growing. The idea of pervasive computing was introduced by Mark Weiser in 1991, with a personal vision of how would be computing in the 21st century. Weiser s idea was that information processing would become part of everyday life, and would be available everywhere. Furthermore, it would be so natural as being invisible in the ambient. To make computing invisible, applications must be proactive, asking for a minimum of user intervention for its operation. An important concept that arises with pervasive computing is the context awareness . Context is any information that can be used to characterize an entity. Based on contextual information, applications can dynamically adapt to the environments in which they operate, becoming proactive and conveying the idea of invisibility. New programming languages or even new paradigms are being developed trying to make more intuitive the programming of pervasive applications. Most of these programming languages attempt to add new features into existing programming languages. However, some authors argue that there must be new formalisms that help to model the properties of pervasive systems, in particular the context awareness. The formal description of a system modeled by formal methods can be used to demonstrate that some properties of the system are correctly modeled. In this sense, this work studies a formal model that can be used as a basis for specifying a new programming language, called Calculus of Context-aware Ambients (CCA), proposed to describe mobile and pervasive applications. Another formal method used in the specification of programming languages are the type systems. Type systems helps to ensure that the system behaves according to the specification, that is, is a way to formally prove the absence of undesirable behavior in a system. Thus, the main contribution of this work is the definition of a type system for the CCA with the focus in the communication between processes. As a case study two real scenarios were modeled using the CCA, demonstrating the use of the type system developed. The preservation (or subject reduction) property of the type system was formally proved, demonstrating that the type system is correct, i.e., achieving the main purpose of the present work.