Agent-Based Middleware for Advanced Communication Services in a Ubiquitous Computing Environment

Introduction

In recent years, studies of ubiquitous computing (ubicomp) (Weiser, 1991) environments and service provision in such environments have increased quickly. Two mainstreams exist in studies of ubiquitous services: research into user contexts in the environment, and service construction schemes. User context studies mainly investigate advanced methods for obtaining a user’s physical location and determine appropriate services from location information and user profiles (Bellavista, 2003). In contrast, studies of service construction propose superior frameworks and schemes designed for dynamic cooperation among system components of many kinds––entities in a ubiquitous environment––to provide user-oriented services (Itao, 2002; Minoh, 2001; Iwamoto, 2003; Minami, 2003; Nakazawa, 2001; Gribble, 2001).

Discussions of actual applications of ubiquitous services have mainly addressed remote control of home electronics appliances from portable devices and information delivery systems based on a user’s location information. Users’ future demands on these ubiquitous services are expected to move into much richer applications such as multimedia communication services. Consequently, we are promoting research and development of fundamental technologies aimed at post-ubiquitous computing environments, including multimedia service provision through cooperative use of audio-visual home electronics appliances. We are targeting services such as video streaming and videoconferencing constructed through coordination of available computers, portable devices and home appliances, as portrayed in Figure 1.

Figure 1.

Application of ubiquitous service provided by multimedia home electric appliances

To provide necessary and sufficient QoS that satisfies user requirements is an intrinsic problem to realize such ubiquitous services. To address this, we must consider not only the user context, but also the resource context of hardware, network, and software. This is true because resource availability tends to be poor and unstable in a ubiquitous environment. Furthermore, multiple users would be given ubiquitous services simultaneously; for that reason, problems of effective resource sharing and assignment should be addressed.

As described in this paper, we are aiming at investigating ubiquitous service construction scheme to provide QoS-aware and stable services against changes of resource status and the user’s situation. We proposed a unique idea of effective handling of multiple contexts including the user context and resource contexts. To accomplish the objective, we apply an agent-based middleware approach.

The remarkable feature of this approach is the agentification of each entity in the overall ubiquitous environment. We embed context management ability and cooperation ability for conflict resolution on multiple contexts to each agent. Furthermore, we provide a maintenance mechanism for the long-term context to accumulate and reuse the history and experiences of past cooperation among agents. The agents’ individual and cooperative behaviors enable QoS-aware service provision. The primary contribution of our work is that it enables provision of rich services, such as multimedia communication services, anytime and at any place with comfortable quality.