Information Technology Reference
In-Depth Information
conveyance of context information and the delivery of adapted and personalised service
content. This multi-agent approach differs from the classic multi-tier architectures in which
the relationships between the components at a particular tier are much stronger.
Conceptually we define different layers in the system architecture in order to present the
functionality of the middleware that is being developed in a more systematic fashion.
Implementation-wise, the middleware architecture is considered as a set of interacting
intelligent agents. Communication between the user mobile devices and the serving
InfoStations could be realized in two ways:
An agent operating within the InfoStation discovers all new devices entering the range
and subsequently initiates communication with them; or
Personal Assistant agents on the user mobile devices are the active part in
communication, and initiate the connection with the InfoStation.
In the current implementation of the prototype architecture, the former approach is used for
Bluetooth communication, whereas the latter applies for WiFi communication.
Figure 4 highlights the main components necessary to ensure continuity to the service
provision, i.e. support for the continuous provision of services and user sessions in the case
of scenario change or resource deficiency. The agents which handle the connection and
session establishment perform different actions, such as:
Searching for and finding mobile devices within the range of an InfoStation;
Creating a list of services required by mobile devices;
Initiation of a wireless connection with mobile devices;
Data transfer to- and from mobile devices.
Also illustrated within Figure 5 are the components which serve to facilitate a level of
context sensitivity and personalisation to the presented services. A short description of the
various agents (for Bluetooth communication) within the architecture is presented below.
The first step in the delivery of the services involves the Scanner agent, which continuously
searches for mobile devices/Personal Assistant agents within the service area of the
InfoStation. In addition, this agent retrieves a list of services required by users (registered on
their mobile devices upon installation of the client part of the application), as well as the
profile information, detailing the context (i.e. device capability and user preference
information. The Scanner agent receives this information in the form of an XML file, which
itself is extracted from the content of an ACL message. The contents of this XML file are then
passed on via the Connection Advisor agent, to the Profile Processor agent, which parses the
received profile and extracts meaningful information. This information can in turn be
utilized to perform the requisite alterations to services and service content.
The information is also very important in relation to the tasks undertaken by the Scenario
Manager agent. The role of this agent is to monitor and respond to changes in the operating
environment, within which the services are operating (i.e. change of mobile device). In the
event of a significant change of service environment, this agent gathers the new capability
and preference information (CPI) via the Scanner agent. Then, in conjunction with the Query
Manager agent and the Content Adaptation agent, facilitates the dynamic adaptation of the
service content to meet the new service context.
