Irene Sygkouna

Context management for the provision of adaptive services to roaming users

Various types of sophisticated networks and terminals are used for the provision of thirdgeneration services, and even more complicated ones are designed for 4G systems. Roaming users will rely on new kinds of wireless networks and terminals to offer mobility and make multimedia services available everywhere. They will, of course, expect continuous access to personalized services from any place, transparently and independent of the underlying network technology and the terminal or point of access. Virtual home environment features were specified and implemented in order to satisfy these requirements in 3G systems. The enhanced role of IP in 4G systems and the assimilation of WLAN technology will enable further advances toward pervasive computing and the pursuit of corn-, plete context awareness in state-of-the-art applications and services. 4G services can he smarter and more adaptive by taking advantage of all types of context available to them within a well defined context management framework. This article presents results from work carried out over the last few years at NTUA,’ bringing us closer to the definition of such a flexible framework for cfficient management of content, which will he able to support the development of advanced telecommunications services and integrated real-time information provision and processing systems.

Context-Aware Services Provisioning on Top of Active Technologies

With respect to the pervasive computing vision, the paper deals with the efficient provisioning of context-aware services making use of Active Networks (ANs) on top of fixed and mobile infrastructure. This represents a starting point for studying on the utilization of Active Technologies in order to provide context-aware services. In these terms, Mobile Agent (MA) Technology comprises a type of Active Technology and the exploitation of its utilization in the field of context-awareness is analyzed. Following, an evaluation comparison of ANs and MAs paradigms is given, identifying the drawbacks and the advantages of each paradigm. Finally, some concluding remarks regarding the combined usage of them are presented.

Enabling distributed QoS management utilizing active network technology

This paper deals with the QoS management issue utilizing the active network technology. The disadvantages of the centralized network management are presented and the current solutions for distributed network management are discussed. The proposed architecture focuses on the QoS management for DiffServ architecture. The improvements that our architecture offers are presented through a service example, which involves QoS configurations.

Experiences with middleware and mobile agents in an e-commerce European project

This paper presents several experiences and conclusions about the usage of the J2EE middleware platform in an e-commerce mediation framework, and introduces mobile agent possibilities within the same environment. The main conclusions are taken from the Smart-EC project, where J2EE and mobility are considered as a value added in its architecture. Other advanced technologies such as XML based multi-device publishing and the utilisation of e-commerce ontologies to handle static and dynamic aspects of complex services or to control their transactional properties, are also considered in the project.

Efficient search mechanisms in a context distribution system

In order to improve systems efficiency and scalability for the provision of time-critical context-aware services, we propose a set of decentralised usage-aware search mechanisms. These mechanisms exploit the locality of reference properties exhibited by context usage patterns with efficient means provided by active networks. Simulation results show that the proposed mechanisms reduce the network traffic while they maintain the good search time of flood broadcasting methods.

Seamless Incorporation of Agents in an E-Commerce Intermediation Platform

This paper describes the realization of a business-to-business intermediation e-commerce platform. The main concern derives from the combined usage of two emerging technologies, namely the Java 2 Enterprise Edition (J2EE) and the Mobile Agent Technology (MAT). The key issues that are addressed in this paper are the following. First, the scenario of the proposed system. Second, the definition of the required functionality and its design by means of appropriate service components based on J2EE principles. Third, the exploitation of agents in terms of their detailed design and implementation activities. Finally, the evaluation of the two interoperable technologies.

Route planning for agent-based information retrieval

This article focuses on Mobile Agents and their use for information retrieval. A multi-agent system is considered; a number of agents are involved in a collective effort to retrieve distributed data from network nodes. Increasing the number of agents may speed-up information retrieval but is burdensome to performance. Initiating with a given number of agents, our objective is to determine the routes of the agents so that the task completion time is minimized. Two known and one new polynomial-time algorithms are tested that produce near-optimal solutions. Simulation results show the cases for which each one is most effective. Additionally, we study the influence of various parameters on the solution. By parametrically varying the number of agents, our method can be used to determine the minimum number that satisfies the desired trade-off between time and performance.

Usage-aware search in peer-to-peer systems

We study solutions to a source discovery problem defined in the framework of providing time-critical context-aware services over a Peer-to-Peer communication paradigm. The proposed mechanisms, which take place in ubiquitous computing environments, exploit the locality of reference properties exhibited by context usage patterns, with efficient means provided by Active Networks. Simulation results show that the new methods reduce network traffic while they maintain the good search time of flood broadcasting methods.

Searching for information in a P2P system

Abstract In relation to decentralized search on top of P2P communication paradigm, we study a proactive mechanism that is based on the dissemination of advertisements for new sources that join a system. The system design goal of limiting the state maintained by each peer and ensuring search efficiency is the driving reason for exploiting the small-world idea, and in particular the hierarchical network model, which provides theoretical bounds on search time. Starting from the study of this theoretical model, we try to reflect it into protocol design. Simulation results testify to the theoretical bounds on search time and provide a quantification view on the search time in relation to the directory capacity requirements of the peers.

A Proactive Mechanism for Efficient Information Discovery

In relation to decentralized search on top of P2P communication paradigm, we study a proactive mechanism that is based on the dissemination of advertisements for new sources that join a system. The system design goal of limiting the state maintained by each peer and ensuring search efficiency is the driving reason for exploiting the small-world idea, and in particular the hierarchical network model that provides theoretical bounds on search time. Starting from the study of this theoretical model, we then tried to reflect it into protocol design. Simulation results testify the theoretical bounds on search time and provide a quantification view on the search time in relation to the directory capacity requirements of the peers