Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

A number of library based parallel and sequential network simulators have been designed. The paper describes a library, called GloMoSim (Global Mobile system Simulator), for parallel simulation of wireless networks. GloMoSim has been designed to be extensible and composable: the communication protocol stack for wireless networks is divided into a set of layers, each with its own API. Models of protocols at one layer interact with those at a lower (or higher) layer only via these APIs. The modular implementation enables consistent comparison of multiple protocols at a given layer. The parallel implementation of GloMoSim can be executed using a variety of conservative synchronization protocols, which include the null message and conditional event algorithms. The paper describes the GloMoSim library, addresses a number of issues relevant to its parallelization, and presents a set of experimental results on the IBM 9076 SP, a distributed memory multicomputer. These experiments use models constructed from the library modules.

GloMoSim: a library for parallel simulation of large-scale wireless networks

[서평]「Component Software」 - Beyond Object-Oriented Programming -

http://www.eis.mdx.ac.uk/staffpages/juanaugusto/CookAJ2009.pdf

Review: Ambient intelligence: Technologies, applications, and opportunities

The Internet of Things (IoT) envisages a future in which digital and physical things or objects (e.g., smartphones, TVs, cars) can be connected by means of suitable information and communication technologies, to enable a range of applications and services. The IoT’s characteristics, including an ultra-large-scale network of things, device and network level heterogeneity, and large numbers of events generated spontaneously by these things, will make development of the diverse applications and services a very challenging task. In general, middleware can ease a development process by integrating heterogeneous computing and communications devices, and supporting interoperability within the diverse applications and services. Recently, there have been a number of proposals for IoT middleware. These proposals mostly addressed wireless sensor networks (WSNs), a key component of IoT, but do not consider RF identification (RFID), machine-to-machine (M2M) communications, and supervisory control and data acquisition (SCADA), other three core elements in the IoT vision. In this paper, we outline a set of requirements for IoT middleware, and present a comprehensive review of the existing middleware solutions against those requirements. In addition, open research issues, challenges, and future research directions are highlighted.

/pdf/middleware-for-internet-of-things-a-survey-5b3i33k9fm.pdf

Middleware for Internet of Things: A Survey

The development of (internet) agents is often a tedious and error-prone task resulting in poorly reusable designs, since both the internal computation of the agent as well as the coordination support are developed in an ad hoc fashion. To improve the process of agent-oriented software development, we propose an agent design method that imposes the separation of internal computation from coordination aspects. This method comprises two dimensions: a design formalism and an agent design process. As an illustration of the presented method, we present the design of an internet agent that is entitled to deploy a distributed service in a computer network, without breaking the consistency of that network. The presented design method has resulted in the development of ACF (Agent Composition Framework), a component framework to build flexible internet agents. We argue that the presented design method combined with this infrastructure can promote a modular and easy to manage approach to the design and development of internet agent applications.

An agent design method promoting separation between computation and coordination

In this paper, we study the problems of thread identity that arise with adapting a local Java program for execution in a distributed environment. When using a distributed control flow programming model like Java RMI or OMG CORBA, the programmer should take into account an inherent shift of semantics. We experienced a particular problem with shift of thread semantics when extending a serialization mechanism for JVM threads to a distributed setting. More specific, we encountered the problem of losing logical thread identity when the control crosses system boundaries. We solved this problem by introduced the generic notion of distributed thread identity in Java programming. Propagation of a globally unique, distributed thread identity provides a uniform mechanism by which all the program’s constituent objects involved in a distributed control flow can uniquely refer to that distributed thread as one and the same computational entity. We have implemented distributed thread identity by means of byte code transformation of application programs. In the paper, we will use the serialization of a distributed execution state as a case to illustrate the value of our Java extension.

Distributed threads in Java

The integration of the notion of distribution in an object-oriented language not only introduces a need for location independent object invocation but also has to cope with various object management operations. These meta-operations include object migration, object replication and granularity control. Additionally, in a multithreaded environment, the concurrency control specifications defined on an object by the application programmer must be realised correctly. Our object invocation scheme offers mechanisms for realising these management operations and concurrency control transparently. This scheme-based on reference objectsis generic in the sense that it can be extented to realise some additional object management operations currently not supported by our prototype. This prototype is realised in a C++ environment on various distributed memory platforms.

A reflective invocation scheme to realize advanced object management

We present a new formalism for modelling concurrent systems, called Petri charts. It is based on Petri nets and statechart principles. It aims at benefiting from the power of both methods in order to provide a modelling method that has substantial expressive power and abstraction functionalities. These appear to be necessary for introducing a formal method into the field of modelling real-world applications. Intuitively, one can say that Petri charts enhance Petri nets by introducing depth: a place (transition) may be refined by a subnet, retaining the original place (transition) as a super-place (super-transition). Besides being a high-level modelling technique, Petri charts allow the combination net refinements and net composition operators, two mechanisms for the modular development of Petri nets. Basic formal definitions and the Petri chart method are presented. We also define a transformation on Petri charts yielding Petri nets. It enables the reuse of the available research results in the area of P/T nets, which is an important benefit.

Pierre Verbaeten

Papers

An agent design method promoting separation between computation and coordination

Distributed threads in Java

A reflective invocation scheme to realize advanced object management

Petri charts: an alternative technique for hierarchical net construction

Towards Hot-Swappable System Software: The DiPS/CuPS Component Framework