Dynamic Virtual Join Point Dispatch

Conceptually, join points are points in the execution of a program and advice is late-bound to them. We propose the notion of virtual join points that makes this concept explicit not only at a conceptual, but also at implementation level. In current implementations of aspect-oriented languages, binding is performed early, at deploy-time, and only a limited residual dispatch is executed. Current implementations fall in the categories of modifying the application code, modifying the meta-level of an application, or interacting with the application by means of events—the latter two already realizing virtual join points to some degree. We provide an implementation of an aspect-oriented execution environment that supports truly virtual join points and discuss how this approach also favors optimizations in the execution environment

Distance learning of foreign languages

doi: 10.1017/S0261444806003727This article provides a critical overview of the field of distance language learning, challenging the way in which the field is often narrowly conceptualised as the development of technology-mediated language learning opportunities. Early sections focus on issues of concept and definition and both theoretical and pedagogical perspectives on the field. Emphasis is placed on evident shifts from a concern with structural and organisational issues to a focus on transactional issues associated with teaching/learning opportunities within emerging paradigms for distance language learning. The next section reviews choices and challenges in incorporating technology into distance language learning environments, foregrounding decisions about technology made in particular sociocultural contexts, the contribution of ‘low-end’ technologies and research directions in developing new learning spaces and in using online technologies. The investigation of learner contributions to distance language learning is an important avenue of enquiry in the field, given the preoccupation with technology and virtual learning environments, and this is the subject of section six. The two final sections identify future research directions and provide a series of conclusions about research and practice in distance language learning as technology-mediated interactions increasingly come to influence the way we think about the processes of language learning and teaching

Component-based simulation for a reconfiguration study of transitic systems

This paper is organized as follows. Part A presents the context of reconfiguring transitic systems and the main idea in implementing the decision step. It comprises sections 1 to 3. Section 3 presents an example that illustrates the concepts presented in the next sections. Parts B and C express the models and principles used to simulate transitic systems, the result of which will be helpful for choosing the new configuration. Part B focuses mainly on models. It comprises sections 4 to 6. Part C focuses mainly on simulation principles. It comprises sections 7 to 10

Abstracting object interactions using composition filters

It is generally claimed that object-based models are very suitable for building distributed system architectures since object interactions follow the client-server model. To cope with the complexity of today's distributed systems, however, we think that high-level linguistic mechanisms are needed to effectively structure, abstract and reuse object interactions. For example, the conventional object-oriented model does not provide high-level language mechanisms to model layered system architectures. Moreover, we consider the message passing model of the conventional object-oriented model as being too low-level because it can only specify object interactions that involve two partner objects at a time and its semantics cannot be extended easily. This paper introduces Abstract Communication Types (ACTs), which are objects that abstract interactions among objects. ACTs make it easier to model layered communication architectures, to enforce the invariant behavior among objects, to reduce the complexity of programs by hiding the interaction details in separate modules and to improve reusability through the application of object-oriented principles to ACT classes. We illustrate the concept of ACTs using the composition filters model

JooFlux: Hijacking Java 7 InvokeDynamic To Support Live Code Modifications

Changing functional and non-functional software implementation at runtime is useful and even sometimes critical both in development and production environments. JooFlux is a JVM agent that allows both the dynamic replacement of method implementations and the application of aspect advices. It works by doing bytecode transformation to take advantage of the new invokedynamic instruction added in Java SE 7 to help implementing dynamic languages for the JVM. JooFlux can be managed using a JMX agent so as to operate dynamic modifications at runtime, without resorting to a dedicated domain-specific language. We compared JooFlux with existing AOP platforms and dynamic languages. Results demonstrate that JooFlux performances are close to the Java ones --- with most of the time a marginal overhead, and sometimes a gain --- where AOP platforms and dynamic languages present significant overheads. This paves the way for interesting future evolutions and applications of JooFlux

Two Decades of Maude

This paper is a tribute to José Meseguer, from the rest of us in the Maude team, reviewing the past, the present, and the future of the language and system with which we have been working for around two decades under his leadership. After reviewing the origins and the language's main features, we present the latest additions to the language and some features currently under development. This paper is not an introduction to Maude, and some familiarity with it and with rewriting logic are indeed assumed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Reflecting in and on post-observation feedback in initial teacher training on certificate courses

This article examines evidence from two studies that concern the nature of post-observation feedback in certificate courses for teaching English to speakers of other languages. It uncovers the main characteristics of these meetings and asks whether there is evidence of reflection in these contexts. In considering reasons why making space for reflection is potentially difficult, the paper also examines the relationship and the role of assessment criteria and how these may impact on opportunities for reflection. The final part of the paper considers how a more reflective approach could be promoted in feedback conferences