Infrastructure for Distributed Applications in Ad Hoc Networks of Small Mobile Wireless Devices

Mobile wireless computing devices such as cellphones, pagers, personal digital assistants, pocket PCs, and tablet computers are all potential platforms for participating in small group, wireless, many-to-many distributed applications. The networking technology needed to support such applications is readily available. However, almost all existing middleware infrastructure for distributed applications was designed for central servers and wired connections. The Anhinga Infrastructure described here runs entirely on the wireless mobile devices and so does not require any central server support. The Anhinga Infrastructure provides a message broadcast ad hoc networking protocol and a distributed computing platform based on lightweight versions of Java, Jini Network Technology, and tuple spaces

Mutation, Aliasing, Viewpoints, Modular Reasoning, and Weak Behavioral Subtyping

Existing work on behavioral subtyping either ignores aliasing or restricts the behavior of additional methods in a subtype and only allows one to use invariants and history constraints in reasoning. This prevents many useful subtype relationships; for example, a type with immutable objects (e.g., immutable sequences), cannot have a behavioral subtype with mutable objects (e.g., mutable arrays). Furthermore, the associated reasoning principle is not very useful, since one cannot use the pre- and postconditions of methods. Weak behavioral subtyping permits more behavioral subtype relationships, does not restrict the behavior of additional methods in subtypes, and allows the use of pre- and postconditions in reasoning. The only cost is the need to restrict aliases so that objects cannot be manipulated through the view of more than one type

Desugaring JML Method Specifications

JML, which stands for ``Java Modeling Language,\u27\u27 is a behavioral interface specification language (BISL) designed to specify Java modules. JML features a great deal of syntactic sugar that is designed to make method specifications more expressive. This paper presents a desugaring process that boils down all of the syntactic sugars in JML method specifications into a much simpler form. This desugaring will help one understand the meaning of these sugars, for example for use in program verification. It may also help manipulation of JML method specifications by tools

An ontology to support evolvable production systems

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de ComputadoresOntologias são cada vez mais um conceito fundamental no suporte à interoperabilidade. Além disso, elas também são fundamentais no suporte aos sistemas evolutivos de produção por duas razões principais. A primeira está relacionada com o facto de a clara identificação e formalização dos processos ser importante para a criação de módulos inteligentes. A segunda razão está relacionada com o facto de os sistemas evolutivos de produção (SEP) serem baseados em sistemas multi-agente que depende em muito, da construção das ontologias de modo a permitir a comunicação entre os agentes pertencentes ao sistema. Os principais conceitos por detrás da ontologia aqui desenvolvida serão os conceitos de processos, tarefas, produto e componentes de manufactura. Esta tese pretende mostrar não só a criação de uma ontologia, mas também de um agente de modo a ser possível a integração da ontologia num sistema multi-agente, no âmbito da manufactura inteligente respondendo às questões envolventes ao paradigma dos sistemas evolutivos de produção. Sabendo que os SEP são baseados em sistemas multi-agente, será também mostrado um agente que irá ter todo o controlo da ontologia e irá pertencer ao sistema de manufactura

Distributed visibility servers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 54-55).This thesis describes techniques for computing conservative visibility exploiting viewpoint prediction, spatial coherence and remote visibility servers to increase the rendering performance of a walk through client. Identifying visible (or partially visible) geometry from an instantaneous viewpoint of a 3-D computer graphics model in real-time is an important problem in interactive computer graphics. Since rendering is an expensive process (due to transformations, lighting and scan-conversion), successfully identifying the exact set of visible geometry before rendering increases the frame-rate of real-time applications. However, computing this exact set is computationally intensive and prohibitive in real-time for large models. For many densely occluded environments that contain a small number of large occluding objects (such as buildings, billboards and houses), efficient conservative visibility algorithms have been developed to identify a set of occluded objects in real-time. These algorithms are conservative since they do not identify the exact set of occluded geometry. While visibility algorithms that identify occluded geometry are useful in increasing the frame-rate of interactive applications, previous techniques have not attempted to utilize a set of workstations connected via a local area network as an external compute resource. We demonstrated a configuration with one local viewer and two remote servers.by Eric A. Brittain.S.M

FOAL 2002 Proceedings: Foundations of Aspect-Oriented Langauges Workshop at AOSD 2002

Aspect-oriented programming is a new area in software engineering and programming languages that promises better support for separation of concerns. The first Foundations of Aspect-Oriented Languages (FOAL) workshop was held at the 1st International Conference on Aspect-Oriented Software Development in Enschede, The Netherlands, on April 22, 2002. This workshop was designed to be a forum for research in formal foundations of aspect-oriented programming languages. The call for papers announced the areas of interest for FOAL as including, but not limited to: formal semantics, formal specification, verification, theory of testing, aspect management, theory of aspect composition, and aspect translation and rewriting. The call for papers welcomed all theoretical and foundational studies of this topic. The goals of this FOAL workshop were to: • Explore the formal foundations of aspect-oriented programming. • Exchange ideas about semantics and formal methods for aspect-oriented programming languages. • Foster interest in the programming language theory communities concerning aspects and aspect- oriented programming languages. • Foster interest in the formal methods community concerning aspects and aspect-oriented programming. In addition, we hoped that the workshop would produce an outline of collaborative research topics and a list of areas for further exploration. The papers at the workshop, which are included in the proceedings, were selected from papers submitted by researchers worldwide. Due to time limitations at the workshop, not all of the submitted papers were selected for presentation

Encapsulation Enforcement with Dynamic Ownership

Unrestricted aliasing is a problem endemic to object oriented programming. It allows notions of encapsulation fundamental to object oriented programming to be violated. This thesis describes ConstrainedJava, an implementation of a language that provides alias control via a much stronger encapsulation guarantees than traditional object-oriented programming languages, integrated with a constraint system. Unlike most existing aliasing control systems, this encapsulation system integrates well with untyped dynamic languages such as ConstrainedJava. This stronger form of encapsulation has been enhanced to make it easier to write practical programs while still providing useful encapsulation guarantees

Encapsulation Enforcement with Dynamic Ownership

Unrestricted aliasing is a problem endemic to object oriented programming. It allows notions of encapsulation fundamental to object oriented programming to be violated. This thesis describes ConstrainedJava, an implementation of a language that provides alias control via a much stronger encapsulation guarantees than traditional object-oriented programming languages, integrated with a constraint system. Unlike most existing aliasing control systems, this encapsulation system integrates well with untyped dynamic languages such as ConstrainedJava. This stronger form of encapsulation has been enhanced to make it easier to write practical programs while still providing useful encapsulation guarantees