Article Preview
TopIntroduction
An increasing number of critical applications require the existence of novel distributed, heterogeneous and dynamic ICT platforms composed of a variety of fixed and mobile processing nodes and networks. Notable examples of such applications are (but not limited to) risk and emergency management, disaster prevention, homeland security and i-mobility. These platforms are characterized by full virtualization of ubiquitous computing resources, data and knowledge bases and services, embedded systems, PDA devices, wearable computers and sensors, interconnected through fixed, mobile and ad-hoc networks. Wireless-based platforms, enabling the robust, flexible and efficient cooperation of mobile components, including both software components and human operators, are of special interest. Users themselves are part of the distributed platform. These platforms, that aim to merge the features of Pervasive Computing and of Grid Computing onto a new emerging paradigm for heterogeneous distributed platforms, can be called Pervasive Mobile Grids (Hingne, Joshi, Finin, Kargupta, & Houstis, 2003; Priol & Vanneschi, 2008).
Figure 1 shows an abstract view of a Pervasive Grid platform, focusing on the heterogeneity of computing resources and on interconnection network technologies. The Pervasive Grid paradigm implies the development, deployment, execution and management of applications that, in general, are dynamic in nature. Dynamicity concerns the number and the specific identification of cooperating components, the deployment and composition of the most suitable versions of software components, processing and networking resources and services, i.e., both the quantity and the quality of the application components to achieve the needed Quality of Service (QoS). The specification and requirements of QoS itself are varying dynamically during the application, according to the user intentions and to the information produced by sensors and services, as well as according to the monitored state and performance of networks and nodes.
Figure 1. A schematic view of a Pervasive Grid infrastructure
The general reference point for this kind of platforms is the Grid paradigm (Bermam, Fox, & Hey, 2003; Foster & Kesselman, 2003) which, by definition, aims to enable the access, selection and aggregation of a variety of distributed and heterogeneous resources and services. However, though notable advancements have been achieved in recent years, current Grid technology is not yet able to supply the needed software tools with the features of high adaptivity, ubiquity, proactivity, self-organization, scalability and performance, interoperability, as well as fault tolerance and security, of the emerging applications running on a very large number of fixed and mobile nodes connected by various kinds of networks.