281 research outputs found
A Generic Module System forWeb Rule Languages: Divide and Rule
An essential feature in practically usable programming languages is
the ability to encapsulate functionality in reusable modules. Modules make large
scale projects tractable by humans. For Web and Semantic Web programming,
many rule-based languages, e.g. XSLT, CSS, Xcerpt, SWRL, SPARQL, and RIF
Core, have evolved or are currently evolving. Rules are easy to comprehend
and specify, even for non-technical users, e.g. business managers, hence easing
the contributions to the Web. Unfortunately, those contributions are arguably
doomed to exist in isolation as most rule languages are conceived without modularity,
hence without an easy mechanism for integration and reuse. In this paper
a generic module system applicable to many rule languages is presented. We
demonstrate and apply our generic module system to a Datalog-like rule language,
close in spirit to RIF Core. The language is gently introduced along the
EU-Rent use case. Using the Reuseware Composition Framework, the module
system for a concrete language can be achieved almost for free, if it adheres to
the formal notions introduced in this paper
Exception handling in the development of fault-tolerant component-based systems
Orientador: Cecilia Mary Fischer RubiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Mecanismos de tratamento de exceçÔes foram concebidos com o intuito de facilitar o gerenciamento da complexidade de sistemas de software tolerantes a falhas. Eles promovem uma separação textual explĂcita entre o cĂłdigo normal e o cĂłdigo que lida com situaçÔes anormais, afim de dar suporte a construção de programas que sĂŁo mais concisos fĂĄceis de evoluir e confĂĄveis. Diversas linguagens de programação modernas e a maioria dos modelos de componentes implementam mecanismos de tratamento de exceçÔes. Apesar de seus muitos benefĂcios, tratamento de exceçÔes pode ser a fonte de diversas falhas de projeto se usado de maneira indisciplinada. Estudos recentes mostram que desenvolvedores de sistemas de grande escala baseados em infra-estruturas de componentes tĂȘm hĂĄbitos, no tocante ao uso de tratamento de exceçÔes, que tornam suas aplicaçÔes vulnerĂĄveis a falhas e difĂceis de se manter. Componentes de software criam novos desafios com os quais mecanismos de tratamento de exceçÔes tradicionais nĂŁo lidam, o que aumenta a probabilidade de que problemas ocorram. Alguns exemplos sĂŁo indisponibilidade de cĂłdigo fonte e incompatibilidades arquiteturais. Neste trabalho propomos duas tĂ©cnicas complementares centradas em tratamento de exceçÔes para a construção de sistemas tolerantes a falhas baseados em componentes. Ambas tĂȘm ĂȘnfase na estrutura do sistema como um meio para se reduzir o impacto de mecanismos de tolerĂąncia a falhas em sua complexidade total e o nĂșmero de falhas de projeto decorrentes dessa complexidade. A primeira Ă© uma abordagem para o projeto arquitetural dos mecanismos de recuperação de erros de um sistema. Ela trata do problema de verificar se uma arquitetura de software satisfaz certas propriedades relativas ao fluxo de exceçÔes entre componentes arquiteturais, por exemplo, se todas as exceçÔes lançadas no nĂvel arquitetural sĂŁo tratadas. A abordagem proposta lança de diversas ferramentas existentes para automatizar ao mĂĄximo esse processo. A segunda consiste em aplicar programação orientada a aspectos (AOP) afim de melhorar a modularização de cĂłdigo de tratamento de exceçÔes. Conduzimos um estudo aprofundado com o objetivo de melhorar o entendimento geral sobre o efeitos de AOP no cĂłdigo de tratamento de exceçÔes e identificar as situaçÔes onde seu uso Ă© vantajoso e onde nĂŁo Ă©Abstract: Exception handling mechanisms were conceived as a means to help managing the complexity of fault-tolerant software. They promote an explicit textual separation between normal code and the code that deals with abnormal situations, in order to support the construction of programs that are more concise, evolvable, and reliable. Several mainstream programming languages and most of the existing component models implement exception handling mechanisms. In spite of its many bene?ts, exception handling can be a source of many design faults if used in an ad hoc fashion. Recent studies show that developers of large-scale software systems based on component infrastructures have habits concerning the use of exception handling that make applications vulnerable to faults and hard to maintain. Software components introduce new challenges which are not addressed by traditional exception handling mechanisms and increase the chances of problems occurring. Examples include unavailability of source code and architectural mismatches. In this work, we propose two complementary techniques centered on exception handling for the construction of fault-tolerant component-based systems. Both of them emphasize system structure as a means to reduce the impactof fault tolerance mechanisms on the overall complexity of a software system and the number of design faults that stem from complexity. The ?rst one is an approach for the architectural design of a system?s error handling capabilities. It addresses the problem of verifying whether a software architecture satis?es certain properties of interest pertaining the ?ow of exceptions between architectural components, e.g., if all the exceptions signaled at the architectural level are eventually handled. The proposed approach is based on a set of existing tools that automate this process as much as possible. The second one consists in applying aspect-oriented programming (AOP) to better modularize exception handling code. We have conducted a through study aimed at improving our understanding of the efects of AOP on exception handling code and identifying the situations where its use is advantageous and the ones where it is notDoutoradoDoutor em CiĂȘncia da Computaçã
Evolution of security engineering artifacts: a state of the art survey
Security is an important quality aspect of modern open software systems. However, it is challenging to keep such systems secure because of evolution. Security evolution can only be managed adequately if it is considered for all artifacts throughout the software development lifecycle. This article provides state of the art on the evolution of security engineering artifacts. The article covers the state of the art on evolution of security requirements, security architectures, secure code, security tests, security models, and security risks as well as security monitoring. For each of these artifacts the authors give an overview of evolution and security aspects and discuss the state of the art on its security evolution in detail. Based on this comprehensive survey, they summarize key issues and discuss directions of future research
Will SDN be part of 5G?
For many, this is no longer a valid question and the case is considered
settled with SDN/NFV (Software Defined Networking/Network Function
Virtualization) providing the inevitable innovation enablers solving many
outstanding management issues regarding 5G. However, given the monumental task
of softwarization of radio access network (RAN) while 5G is just around the
corner and some companies have started unveiling their 5G equipment already,
the concern is very realistic that we may only see some point solutions
involving SDN technology instead of a fully SDN-enabled RAN. This survey paper
identifies all important obstacles in the way and looks at the state of the art
of the relevant solutions. This survey is different from the previous surveys
on SDN-based RAN as it focuses on the salient problems and discusses solutions
proposed within and outside SDN literature. Our main focus is on fronthaul,
backward compatibility, supposedly disruptive nature of SDN deployment,
business cases and monetization of SDN related upgrades, latency of general
purpose processors (GPP), and additional security vulnerabilities,
softwarization brings along to the RAN. We have also provided a summary of the
architectural developments in SDN-based RAN landscape as not all work can be
covered under the focused issues. This paper provides a comprehensive survey on
the state of the art of SDN-based RAN and clearly points out the gaps in the
technology.Comment: 33 pages, 10 figure
Analysis as first-class citizens â an application to Architecture Description Languages
Architecture Description Languages (ADLs) support modeling and analysis of systems through models transformation and exploration. Various contributions made proposals to bring verification capabilities to designers through model-based frame- works and illustrated benefits to the overall system quality. Model-level analyses are usually performed as an exogenous, unidirectional and semantically weak transformation towards a third-party model. We claim such process can be incomplete and/or inefficient because gathered results lead to evolution of the primary model. This is particularly problematic for the design of Distributed Real-Time Embedded (DRE) systems that has to tackle many concerns like time, security or safety. In this paper, we argue why analysis should no longer be considered as a side step in the design process but, rather, should be embedded as a first-class citizen in the model itself. We review several standardized architecture description languages, which consider analysis as a goal. As an element of solution, we introduce current work on the definition of a language dedicated to the analysis of models within the scope of one particular ADL, namely the Architecture Analysis and Design Language (AADL)
From manufacturing to design : an essay on the work of Kim B. Clark. Harvard Business School Working Paper- 07-057
In this paper, we describe Clark's research and discuss his contributions to management scholarship and economics. We look at three distinct bodies of work. In the first, Clark (in conjunction with Robert Hayes and Steven Wheelwright) argued that the abandonment by U.S. managers of manufacturing as a strategic function exposed U.S. companies to Japanese competition in terms of the cost and quality of goods. In the second, conducted with Wheelwright, Bruce Chew, Takahiro Fujimoto, Kent Bowen and Marco Iansiti, Clark made the case that product development could be managed in new ways that would lead to significant competitive advantage for firms. Finally, in work conducted with Abernathy, Rebecca Henderson and Carliss Baldwin, Clark placed product and process designs at the center of his explanation of how innovation determines the structure and evolution of industries.
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Requirements-Driven Adaptation of Choreographed Interactions
Electronic services are emerging as the de-facto enabler of interaction interoperability across organization boundaries. Cross-organizational interactions are often âchoreographedâ, i.e. specified by a messaging protocol from a global point of view independent of the local view of each interacting organization. Local requirements motivating an interaction as well as the global contextual requirements governing the interaction inevitably evolve over time, requiring adaptation of the corresponding interaction protocol. Adaptation of an interaction protocol must ensure the satisfaction of both sets of interaction requirements while maintaining consistency between the global view and the local views of an interaction specification. Such adaptation is not possible with the current state-of-the-art representations of choreographed interactions, as they capture only operational messaging specifications detached from both local organizational requirements as well as global contextual requirements.
This thesis presents three novel contributions that tackle adaptation of choreographed interaction protocols: an automated technique for deriving an interaction protocol from requirements, a formalization of consistency between local and global views, and a framework for guiding the adaptation of a choreographed interaction. A choreographed interaction is specified using models of organizational requirements motivating the interaction. We employ the formal semantics embedded in requirements models to automatically derive an interaction protocol. We propose a framework for relating the global and local views of interaction specification and maintaining consistency between them. We develop a metamodel for interaction specification, from which we enumerate adaptation operations. We build a catalogue that provides guidance on performing each operation and propagating changes between the global and local views. These contributions are evaluated using examples from the literature as well as a real-world case study
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