Applications of Wireless Sensor Networks

Today the researchers want to collect as much data as possible from different locations for monitoring reasons. In this context large-scale wireless sensor networks are becoming an active topic of research (Kahn1999). Because of the different locations and environments in which these sensor networks can be used, specific requirements for the hardware apply. The hardware of the sensor nodes must be robust, provide sufficient storage and communication capabilities, and get along with limited power resources. Sensor nodes such as the Berkeley-Mote Family (Polastre2006, Schmitt2006) are capable of meeting these requirements. These sensor nodes are small and light devices with radio communication and the capability for collecting sensor data. In this chapter the authors review the key elements for sensor networks and give an overview on possible applications in the field of monitoring.

Agent-Based Infrastructure for Dynamic Composition of Grid Services

The service-oriented computing paradigm is based on the assumption that existing services can be put together in order to obtain new composite services. This chapter focuses on how peer-to-peer architectures based on multi-agent systems can be used to build highly dynamic and reconfigurable infrastructure that support dynamic composition of grid services. The chapter starts by providing an overview of key technologies for SOC. It then introduces dynamic service composition and challenges of composing grid services. The authors further motivate for Multi-agent system approach in SOC and why it becomes important in service composition. They then present our research effort, AIDSEC, an agent-based infrastructure for dynamic service composition, describing its architecture, implementation and comparison with some related work in the literature. In addition, the chapter raises some emerging trends in SOC and the particular challenges they pose to service composition. They conclude by suggesting that a solution based on multi-agent system is required for composing services that possess capabilities of autonomy, reliability, flexibility, and robustness.

Trust Calculation and Management in P2P and Grid Systems

The significance of efficient security mechanisms in P2P and Grid systems is unquestionable, since security is considered to be a quality of service factor for such systems. Traditional security mechanisms in P2P and Grid systems include encryption, sand-boxing and other access control and authentication mechanisms. Unfortunately these techniques incur additional overhead. By using trust and reputation-based mechanisms, the additional overhead is minimized. The deployment of efficient trust mechanisms results to a safer communication between P2P or Grid nodes, increasing the quality of service and making P2P and Grid technology more appealing. The aim of this book chapter is to lay the theoretical background of concepts such as trust, reputation, trust graphs and trust functions. Furthermore it presents classification schemes for trust functions, discussing the characteristics and differences of each classification. Finally, it analyses popular trust and reputation-based management mechanisms that have been implemented in both P2P and Grid systems.

Distributed and Adaptive Service Discovery Using Preference

In Service-Oriented Computing, service providers publish their services by deploying service components which implement those services into a network. Since such services are distributed around the network, Service-Oriented Computing requires the functionality to discover the services that meet certain criteria specified by an end user. In order to overcome the scalability issue that the current centralized discovery mechanism inherently has, distributed discovery mechanisms that the P2P research community has developed may be promising alternatives. This chapter outlines existing distributed mechanisms and proposes a novel discovery mechanism that utilizes end users’ preferences. The proposed mechanism allows end users to return their feedback that describes the degree of the preference for discovered services. The returned preference information is stored at nodes and utilized to decide where to forward subsequent queries. The extensive simulation demonstrates that the proposed mechanism meets key requirements such as selectivity, efficiency and adaptability.

Service-Oriented Architectures for Pervasive Computing

The vision of pervasive computing is to create and manage computational spaces where large numbers of heterogeneous devices collaborate transparently to serve the user tasks all the time, anywhere. The original utility of a computer is now changing from a stand-alone tool that runs software applications to an environment-aware, context-aware tool that can enhance the user experience by executing services and carrying out his/her tasks in an efficient manner. However, the heterogeneity of devices and the user’s mobility are among the many issues that make developing pervasive computing applications a very challenging task. A solution to the programmability of pervasive spaces is adopting the service-oriented architecture (SOA) paradigm. In the SOA model, device capabilities are exposed as software services thus providing the programmer with a convenient abstraction level that can help to deal with the dynamicity of pervasive spaces. In this chapter the authors review the state of the art in SOA-based pervasive computing, identify existing open problems, and contribute ideas for future research.

Taxonomy of Grid Systems

Advances in Grid computing are stimulating the emergence of novel types of Grids. Accessible Grids, manageable Grids, interactive Grids and personal Grids represent a significant evolution of Grid computing. More and more researchers are realising the potentials of emerging Grids in bridging the current gap between Grid technologies and end users. Nevertheless, no reviews or classifications on emerging Grids are available. Therefore, this chapter aims to give a review on Grid systems. It sets out to develop a comprehensive classification of both traditional and emerging Grid systems with an aim to motivate further research and to assist in establishing a solid foundation in such a rapidly developing and expanding field.

A Survey of Peer-to-Peer Architectures for Service Oriented Computing

Peer-to-peer file sharing has become popular for many kinds of resource location and distribution applications including file sharing, distributed computation, multi-media messaging and content distribution. Peer-to-peer approaches also have significant potential for supporting large scale, decentralised service oriented computing. This chapter discusses each class of contemporary P2P architecture in turn and discusses the suitability of each architecture class for supporting service oriented computing. Future trends in peer-to-peer architectures are then discussed and multi-layer peer-to-peer architectures are highlighted as a promising platform for supporting service oriented computing. This chapter then concludes with a discussion of outstanding issues that must be addressed before peer-to-peer architectures can offer adequate support for service oriented computing.

Electronic Business Contracts Between Services

Electronic contracts mirror the paper versions exchanged between businesses today, and offer the possibility of dynamic, automatic creation and enforcement of restrictions and compulsions on service behaviour that are designed to ensure business objectives are met. Where there are many contracts within a particular application, it can be difficult to determine whether the system can reliably fulfil them all, yet computer-parsable electronic contracts may allow such verification to be automated. In this chapter, the authors describe a conceptual framework and architecture specification in which normative business contracts can be electronically represented, verified, established, renewed, and so on. In particular, they aim to allow systems containing multiple contracts to be checked for conflicts and violations of business objectives. They illustrate the framework and architecture with an aerospace aftermarket example.

Adaptive Query Processing in Data Grids

The data grid integrates wide-area autonomous data sources and provides users with a unified data query and processing infrastructure. Adaptive data query and processing is required by data grids to provide better quality of services (QoS) to users and applications in spite of dynamically changing resources and environments. Existing AQP techniques can only meet partially data grid requirements. Some existing work is either addressing domain-specific or single-node query processing problems. Data grids provide new mechanisms for monitoring and discovering data and resources in a cross-domain wide area. Data query in grids can benefit from this information and provide better adaptability to the dynamic nature of the grid environment. In this work, an adaptive controller is proposed that dynamically adjusts resource shares to multiple data query requests in order to meet a specified level of service differentiation. The controller parameters are automatically tuned at runtime based on a predefined cost function and an online learning method. Simulation results show that our controller can meet given QoS differentiation targets and adapt to dynamic system resources among multiple data query processing requests while total demand from users and applications exceeds system capability.

Enforcing Fairness in Asynchronous Collaborative Environments

Many large-scale distributed applications rely on collaboration, where unrelated users or organizations share their resources for everyone’s benefit. However, in such environments any node may attempt to maximize its own benefit by exploiting other’s resources without contributing back. Collaborative systems must therefore deploy strategies to fight free-riders, and enforce collaborative behavior. This chapter explores a family of mechanisms to enforce fairness in asynchronous collaborative environments, where simple tit-for-tat policies cannot be used. Our solutions rely on enforced neighborhood relations, where each node is restricted in the choice of other nodes to collaborate with. This creates long-term collaboration relationships, where each node must behave well with its neighbors if it wants to be able to use their resources.