Algebraic specifications and refinement for component-based development using RAISE

There are two main activities in Component-Based Development: component development, where we build libraries for general use, and component integration, where we assemble an application from existing components. In this work, we analyze how to apply algebraic specifications with refinement to component development. So we restrict our research to the use of modules that are described as class expressions in a formal specification language, and we present several refinement steps for component development, introducing in each one design decisions and implementation details. This evolution starts from the initial specification of a component as an abstract module, and finishes with the final deployment as fully implemented code. The usage of formal tools helps to assure the correctness of each step, and provides the ground to introduce complementarytechniques, such as bisimulations, for the process of component integration.Facultad de Informátic

Formal specifications in component-based development

Software engineering has entered a new era, the Internet and its associated technologies require a different conceptual framework for building and understanding software solutions. Users ask to develop applications more rapidly, and software engineers need to ensamble systems from preexisting parts. Components and Components-Based Development( CBD), are the approaches that provide solutions to these arising needs. Components are the way to encapsulate existing functionality, acquire third-party solutions, and build new services to support emerging business processes. Component-based development provides a design paradigm that is well suited to the new requirements, were the traditional design and build has been replaced by select and integrate. Within this approach, the specification of components plays a crucial role. If we are working on the development of components in order to construct a library for general use, we need to start from a concrete and complete specification of what we are going to construct. If we are assembling our application from pre-existing components, we need a precise specification of the behaviour of the component in order to select it from the library.Eje: Ingeniería de Software y Base de DatosRed de Universidades con Carreras en Informática (RedUNCI

Formal specifications in component-based development

Software engineering has entered a new era, the Internet and its associated technologies require a different conceptual framework for building and understanding software solutions. Users ask to develop applications more rapidly, and software engineers need to ensamble systems from preexisting parts. Components and Components-Based Development( CBD), are the approaches that provide solutions to these arising needs. Components are the way to encapsulate existing functionality, acquire third-party solutions, and build new services to support emerging business processes. Component-based development provides a design paradigm that is well suited to the new requirements, were the traditional design and build has been replaced by select and integrate. Within this approach, the specification of components plays a crucial role. If we are working on the development of components in order to construct a library for general use, we need to start from a concrete and complete specification of what we are going to construct. If we are assembling our application from pre-existing components, we need a precise specification of the behaviour of the component in order to select it from the library.Eje: Ingeniería de Software y Base de DatosRed de Universidades con Carreras en Informática (RedUNCI

Reconfigurable component connectors

This thesis provides formal methods for reconfigurable component connectors.UBL - phd migration 201

From computability to executability : a process-theoretic view on automata theory

The theory of automata and formal language was devised in the 1930s to provide models for and to reason about computation. Here we mean by computation a procedure that transforms input into output, which was the sole mode of operation of computers at the time. Nowadays, computers are systems that interact with us and also each other; they are non-deterministic, reactive systems. Concurrency theory, split off from classical automata theory a few decades ago, provides a model of computation similar to the model given by the theory of automata and formal language, but focuses on concurrent, reactive and interactive systems. This thesis investigates the integration of the two theories, exposing the differences and similarities between them. Where automata and formal language theory focuses on computations and languages, concurrency theory focuses on behaviour. To achieve integration, we look for process-theoretic analogies of classic results from automata theory. The most prominent difference is that we use an interpretation of automata as labelled transition systems modulo (divergence-preserving) branching bisimilarity instead of treating automata as language acceptors. We also consider similarities such as grammars as recursive specifications and finite automata as labelled finite transition systems. We investigate whether the classical results still hold and, if not, what extra conditions are sufficient to make them hold. We especially look into three levels of Chomsky's hierarchy: we study the notions of finite-state systems, pushdown systems, and computable systems. Additionally we investigate the notion of parallel pushdown systems. For each class we define the central notion of automaton and its behaviour by associating a transition system with it. Then we introduce a suitable specification language and investigate the correspondence with the respective automaton (via its associated transition system). Because we not only want to study interaction with the environment, but also the interaction within the automaton, we make it explicit by means of communicating parallel components: one component representing the finite control of the automaton and one component representing the memory. First, we study finite-state systems by reinvestigating the relation between finite-state automata, left- and right-linear grammars, and regular expressions, but now up to (divergence-preserving) branching bisimilarity. For pushdown systems we augment the finite-state systems with stack memory to obtain the pushdown automata and consider different termination styles: termination on empty stack, on final state, and on final state and empty stack. Unlike for language equivalence, up to (divergence-preserving) branching bisimilarity the associated transition systems for the different termination styles fall into different classes. We obtain (under some restrictions) the correspondence between context-free grammars and pushdown automata for termination on final state and empty stack. We show how for contrasimulation, a weaker equivalence than branching bisimilarity, we can obtain the correspondence result without some of the restrictions. Finally, we make the interaction within a pushdown automaton explicit, but in a different way depending on the termination style. By analogy of pushdown systems we investigate the parallel pushdown systems, obtained by augmenting finite-state systems with bag memory, and consider analogous termination styles. We investigate the correspondence between context-free grammars that use parallel composition instead of sequential composition and parallel pushdown automata. While the correspondence itself is rather tight, it unfortunately only covers a small subset of the parallel pushdown automata, i.e. the single-state parallel pushdown automata. When making the interaction within parallel pushdown automata explicit, we obtain a rather uniform result for all termination styles. Finally, we study computable systems and the relation with exective and computable transition systems and Turing machines. For this we present the reactive Turing machine, a classical Turing machine augmented with capabilities for interaction. Again, we make the interaction in the reactive Turing machine between its finite control and the tape memory explicit

Automata-theoretic protocol programming : parallel computation, threads and their interaction, optimized compilation, [at a] high level of abstraction

In the early 2000s, hardware manufacturers shifted their attention from manufacturing faster—yet purely sequential—unicore processors to manufacturing slower—yet increasingly parallel—multicore processors. In the wake of this shift, parallel programming became essential for writing scalable programs on general hardware. Conceptually, every parallel program consists of workers, which implement primary units of sequential computation, and protocols, which implement the rules of interaction that workers must abide by. As programmers have been writing sequential code for decades, programmingand mutual exclusion may serve as a target for compilation. To demonstrate the practical feasibility of the GPL+DSL approach to protocol programming, I study the performance of the implemented compiler and its optimizations through a number of experiments, including the Java version of the NAS Parallel Benchmarks. The experimental results in these benchmarks show that, with all four optimizations in place, compiler-generated protocol code can competewith hand-crafted protocol code. workers poses no new fundamental challenges. What is new—and notoriously difficult—is programming of protocols. In this thesis, I study an approach to protocol programming where programmers implement their workers in an existing general-purpose language (GPL), while they implement their protocols in a complementary domain-specific language (DSL). DSLs for protocols enable programmers to express interaction among workers at a higher level of abstraction than the level of abstraction supported by today’s GPLs, thereby addressing a number of protocol programming issues with today’s GPLs. In particular, in this thesis, I develop a DSL for protocols based on a theory of formal automata and their languages. The specific automata that I consider, called constraint automata, have transition labels with a richer structure than alphabet symbols in classical automata theory. Exactly these richer transition labels make constraint automata suitable for modeling protocols.Constraint automata constitute the (denotational) semantics of the DSL presented in this thesis. On top of this semantics, I use two complementary syntaxes: an existing graphical syntax (based on the coordination language Reo) and a novel textual syntax. The main contribution of this thesis, then, consists of a compiler and four of its optimizations, all formalized and proven correct at the semantic level of constraint automata, using bisimulation. In addition to these theoretical contributions, I also present an implementation of the compiler and its optimizations, which supports Java as the complementary GPL, as plugins for Eclipse. Nothing in the theory developed in this thesis depends on Java, though; any language that supports some form of threading.<br/