The separation of concerns, as a conceptual tool, enables us to manage the complexity of the software systems that we develop. Such was the intent behind the OORAM [7]. When the idea is taken further to software packa...
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ISBN:
(纸本)0769515886
The separation of concerns, as a conceptual tool, enables us to manage the complexity of the software systems that we develop. Such was the intent behind the OORAM [7]. When the idea is taken further to software packaging, greater reuse and maintainability are achieved. There have been a number of approaches aimed at modularizing software around the natural boundaries of the various concerns, including subject-oriented programming [2] aspect-oriented programming [3], and our own view-oriented programming [4]. The same applications that warrant the kind of separation supported by the above techniques tend also to be distributed where different users may be interested in different aspects of the application at different times. In this paper, we look at distribution in the context of the separation of concerns, and present an approach to distributing objects that embed different aspects.
Scaling applications to large networks and an increasing number of users has been since years a technical challenge. Today, technologies are well known to scale applications to local net-works but scaling to large net...
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ISBN:
(纸本)0769515886
Scaling applications to large networks and an increasing number of users has been since years a technical challenge. Today, technologies are well known to scale applications to local net-works but scaling to large networks with high latency is still a challenge. DLBS (Dynamic Load Balancing Service) brings new solutions regarding large scale load balancing for middleware based applications. DLBS offers a multi-criteria and easily customizable load balancing service. It consists of a scalable monitoring infrastructure, a connection manager (integrated into the middleware) and customizable load balancing strategies. Implementation of a low level service requires in order to stay efficient to avoid the necessity for high overhead. DLBS aims to be a generic load balancing service and an easy and efficient portability with a CORBA Object Request Broker has been possible thanks to Aspect Oriented programming.
The aim of our ongoing research is to give a method to construct intelligent tutoring systems for agents who are executing typical procedures in dynamic environments based on a logical framework. Typical procedures ar...
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ISBN:
(纸本)0769518672
The aim of our ongoing research is to give a method to construct intelligent tutoring systems for agents who are executing typical procedures in dynamic environments based on a logical framework. Typical procedures are similar to plans in the sense that they describe the actions an agent should execute to achieve a certain goal. In this paper we address what we consider is the first step toward the construction of this kind of systems: procedure recognition. We formalize what does it mean that an agent is performing a procedure in the Situation Calculus [12], a logical first-order language extended with induction. Based upon this formalization, we give two different implementations. The first, which is directly based in our formalization, is proved to be quite inefficient. The second, significantly more efficient, arises from a logical reformulation of the original formalization. Procedures are represented through CON-GOLOG [6] programs, a logical interpreted language based on the Situation Calculus.
This paper summarizes an actor-based middleware in Java for the development of time-dependent distributed systems. The approach centres on the separation of concerns. Functional, synchronization, control and configura...
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ISBN:
(纸本)0769515886
This paper summarizes an actor-based middleware in Java for the development of time-dependent distributed systems. The approach centres on the separation of concerns. Functional, synchronization, control and configuration aspects of an application can separately be dealt with in a design so as to favour the fulfilment of the application requirements. Actors are encapsulation units of data and behaviour and are modelled as finite state machines. They enable ubiquitous computing. Actors have location transparent names and can migrate, possibly autonomously, from node to node of an heterogeneous computing infrastructure like Internet, for accomplishing their computational task. Actors are based on an explicit messaging system. Crosscutting concerns in group of actors can be programmed in special actors (synchronizers) which transparently filter message exchanges and superimpose to them timing and synchronization constraints which directly affect message scheduling. The paper describes the implementation of a real-time multimedia QoS synchronizer.
As the peer-to-peer (P2P) computing paradigm receives more and more attention, it is now necessary to provide computing platforms to offer an environment to build P2P applications. In this paper, we describe Rheeve, a...
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ISBN:
(纸本)0769515886
As the peer-to-peer (P2P) computing paradigm receives more and more attention, it is now necessary to provide computing platforms to offer an environment to build P2P applications. In this paper, we describe Rheeve, a computing platform that provides support for the development of HTTP-enabled, efficient and fault-tolerant P2P applications. Rheeve has a highly modular system architecture and scalable mechanisms for efficient peer connections and service discovery and delivery. Its work-distribution and execution facility enables sharing of computation resources in a language and protocol independent manner. Rheeve also provides a visual programming interface, which, together with the underlying JavaBeans technology, supports a plug-n-play style of application design.
This paper addresses the fundamental tradeoffs in event systems between scalability (of event filtering, routing, and delivery mechanisms), expressiveness (when describing interests in events), and event safety (ensur...
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ISBN:
(纸本)0769515886
This paper addresses the fundamental tradeoffs in event systems between scalability (of event filtering, routing, and delivery mechanisms), expressiveness (when describing interests in events), and event safety (ensuring encapsulation and type-safe interaction with polymorphic events). We point out some ramifications underlying these tradeoffs and we propose a pragmatic approach to handle them. We achieve scalability using a multi-stage-filtering strategy that combines approximate and perfect matching techniques for the purpose of event routing and filtering. We achieve expressiveness and event safety by viewing events as objects, i.e., instances of application-defined abstract types.
One of the problems faced by large, global organizations and enterprises is to effectively enable their employees to collaborate across locations. People need collaborative work support while they, are on the move and...
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ISBN:
(纸本)0769515886
One of the problems faced by large, global organizations and enterprises is to effectively enable their employees to collaborate across locations. People need collaborative work support while they, are on the move and have to share business documents and know-how. Although much work has been done in the area of Computer Supported Collaborative Work (CSCW) to date, supporting mobility is only recently receiving attention. Hence, most of the existing approaches do not deal with emerging mobile teamwork requirements such as locating business documents and expertise through distributed searches, advanced subscription and notification, community building, and mobile information sharing and access. Furthermore, existing applications and approaches are usually difficult to customize to business-specific processes and requirements. The MObile Teamwork Infrastructure for Organizations Networking (MOTION)(1) system addresses these requirements and provides a generic teamwork services Application programming Interface (API), TWSAPI, that can be used to build organization-specific collaborative applications. In this paper, we give an overview of the MOTION TWSAPI and illustrate its usage in building an application that provides document review support.
Current visual programming environments offer a variety of composition possibilities. Most of these environments provide drag and drop facilities of components on a form and let the interaction between components be d...
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ISBN:
(纸本)0769518672
Current visual programming environments offer a variety of composition possibilities. Most of these environments provide drag and drop facilities of components on a form and let the interaction between components be defined by selecting suitable components and checking the incompatibilities of the resulting composition. Thus, special nature of component-based development environments induces requirements for capabilities such as identification, retrieval and integration of components. This paper proposes a framework for comparing visual component composition techniques and environments. We identify basic and specific features that compose the framework and we show its use by comparing four visual composition environments.
With modern software systems, an important requirement is the ability to be auto adaptive, i.e. being able to adjust itself its changing environment. In line with this, a run time manager for dynamic feature integrati...
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ISBN:
(纸本)0769515886
With modern software systems, an important requirement is the ability to be auto adaptive, i.e. being able to adjust itself its changing environment. In line with this, a run time manager for dynamic feature integration of telecommunication systems, interaction detection and resolution is described in this paper with aspects being used to implement features. The manager manages the interaction of features/aspects by monitoring the managed program. The program is represented by a labelled transition system (LTS) model, stored in a flexible data structure, and executed by calling action subroutine represented by the label of the LTS model, forming a reflective facility for the composition and analysis of features. It is the reflective mechanism that makes dynamic feature addition, run time model checking, as well as adaptive interaction resolution possible. Runtime model checking is possible because the checked program is stored within itself and the interaction resolution will be done by selecting behaviour traces according to the resolution rules.
We consider an extension of linear-time temporal logic (LTL) with constraints interpreted over a concrete domain. We use a new automata-theoretic technique to show PSPACE decidability of the logic for the constraint s...
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ISBN:
(纸本)3540002251
We consider an extension of linear-time temporal logic (LTL) with constraints interpreted over a concrete domain. We use a new automata-theoretic technique to show PSPACE decidability of the logic for the constraint system (Z, <, =) and (N, <, =). We also give an automata-theoretic proof of a result of Balbiani and Condotta [BCO] for constraint systems that satisfy a "completion" property.
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