2,427 research outputs found
Incorporating prediction models in the SelfLet framework: a plugin approach
A complex pervasive system is typically composed of many cooperating
\emph{nodes}, running on machines with different capabilities, and pervasively
distributed across the environment. These systems pose several new challenges
such as the need for the nodes to manage autonomously and dynamically in order
to adapt to changes detected in the environment. To address the above issue, a
number of autonomic frameworks has been proposed. These usually offer either
predefined self-management policies or programmatic mechanisms for creating new
policies at design time. From a more theoretical perspective, some works
propose the adoption of prediction models as a way to anticipate the evolution
of the system and to make timely decisions. In this context, our aim is to
experiment with the integration of prediction models within a specific
autonomic framework in order to assess the feasibility of such integration in a
setting where the characteristics of dynamicity, decentralization, and
cooperation among nodes are important. We extend an existing infrastructure
called \emph{SelfLets} in order to make it ready to host various prediction
models that can be dynamically plugged and unplugged in the various component
nodes, thus enabling a wide range of predictions to be performed. Also, we show
in a simple example how the system works when adopting a specific prediction
model from the literature
A Framework to Generate 3D Learning Experience
A Collaborative Virtual Environment (CVE) is a computer-based virtual space that supports collaborative work and social interplay. In a 3D CVE, a āhostingā 3D world is the necessary
ingredient: within it users provided with graphical embodiments called avatars that convey their identity (presence, location, movement etc.), can meet and interact with other users,
with agents or with virtual objects. Even if graphics hardware and 3D technologies are rapidly evolving and the increased Internet connection speed allows the sharing of amounts of data and information among geographically distributed users, the development of networked three-dimensional applications is still complicated and requires expert knowledge. Although some collaborative 3D Web technologies and applications have already been developed, most of them are particularly concerned with offering a high level realistic representation of the
virtual world since increasing the level of detail increases the sense of āvirtual presenceā in the 3D world. However, these developments have not, at the same time supported a high
level, non-expert authoring process and the concepts of programming flexibility and component re-use have rarely been taken into account.
In this introduction, we discuss our research experience in the field of Collaborative Virtual Environments. We will outline our approach which has been based on both multi-channel
integration and on high performances issues
Transaction management in object-oriented data base systems
Object-oriented data bases are fast gaining in popularity, especially with the advent of advanced applications like computer aided design (CAD) and multimedia data bases (MMDB). The modeling techniques required by these applications cannot be met by conventional data base systems. The semantic richness of the object-oriented model facilitates the modeling of advanced data base applications. These applications are characterized by long-duration cooperating transactions. Unlike the conventional data bases, serializability can no linger be the correctness criterion for concurrent transaction execution. A new transaction model for object-oriented data bases is needed. This dissertation describes our research in the area of transaction management for object-oriented data bases. A new transaction model for object-oriented data bases is defined. This model takes into consideration the unique requirements of the advanced applications. Data base consistency is now defined in terms of correctability. Object-oriented Correct Schedules (OOCS) and Object-oriented Correctable Schedules (OOCLS) are defined. This dissertation also describes a new concurrency control protocol that satisfies the correctness criterion for concurrent execution of transactions in an object-oriented data base environment, i.e. it allows only Object-oriented Correctable Schedules. Users of a data base interact with it through means of queries. Queries are then translated into transactions. The data base functionality necessary to support queries is also discussed in this research work
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Towards an aspect weaving BPEL engine
This position paper proposes the use of dynamic aspects and
the visitor design pattern to obtain a highly configurable and
extensible BPEL engine. Using these two techniques, the
core of this infrastructural software can be customised to
meet new requirements and add features such as debugging,
execution monitoring, or changing to another Web Service
selection policy. Additionally, it can easily be extended to
cope with customer-specific BPEL extensions. We propose
the use of dynamic aspects not only on the engine itself
but also on the workflow in order to tackle the problems of
Web Service hot deployment and hot fixes to long running
processes. In this way, composing aWeb Service "on-the-fly"
means weaving its choreography interface into the workflow
On Agent-Based Software Engineering
Agent-based computing represents an exciting new synthesis both for Artificial Intelligence (AI) and, more generally, Computer Science. It has the potential to significantly improve the theory and the practice of modeling, designing, and implementing computer systems. Yet, to date, there has been little systematic analysis of what makes the agent-based approach such an appealing and powerful computational model. Moreover, even less effort has been devoted to discussing the inherent disadvantages that stem from adopting an agent-oriented view. Here both sets of issues are explored. The standpoint of this analysis is the role of agent-based software in solving complex, real-world problems. In particular, it will be argued that the development of robust and scalable software systems requires autonomous agents that can complete their objectives while situated in a dynamic and uncertain environment, that can engage in rich, high-level social interactions, and that can operate within flexible organisational structures
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