FH-MAC

In this article, the authors propose a new hybrid MAC protocol named H-MAC for wireless mesh networks. This protocol combines CSMA and TDMA schemes according to the contention level. In addition, it exploits channel diversity and provides a medium access control method that ensures the QoS requirements. Using ns-2 simulator, we have implemented and compared H-MAC with other MAC protocol used in Wireless Network. The results showed that H-MAC performs better compared to Z-MAC, IEEE 802.11 and LCM-MAC.

Push-based Prefetching in Remote Memory Sharing System

Remote memory sharing systems aim at the goal of improving overall performance using distributed computing nodes with surplus memory capacity. To exploit the memory resources connected by the high-speed network, the user nodes, which are short of memory, can obtain extra space provision. The performance of remote memory sharing is constrained with the expensive network communication cost. In order to hide the latency of remote memory access and improve the performance, we proposed the push-based prefetching to enable the memory providers to push the potential useful pages to the user nodes. For each provider, it employs sequential pattern mining techniques, which adapts to the characteristics of memory page access sequences, on locating useful memory pages for prefetching. We have verified the effectiveness of the proposed method through trace-driven simulations.

Self-Configuration and Administration of Wireless Grids

A Wireless Grid is an augmentation of a wired grid that facilitates the exchange of information and the interaction between heterogeneous wireless devices. While similar to the wired grid in terms of its distributed nature, the requirement for standards and protocols, and the need for adequate Quality of Service; a Wireless Grid has to deal with the added complexities of the limited power of the mobile devices, the limited bandwidth, and the increased dynamic nature of the interactions involved. This complexity becomes important in designing the services for mobile computing. A grid topology and naming service is proposed which can allow self-configuration and self-administration of various possible wireless grid layouts.

A Policy-Based Security Framework for Privacy-Enhancing Data Access and Usage Control in Grids

In this chapter, we first summarize an analysis of the differences between Grids and the previously dominant model of inter-organizational collaboration. Based on requirements derived thereof, we specify a security framework that demonstrates how well-established policy-based privacy management architectures can be extended to provide the required Grid-specific functionality. We also discuss the necessary steps for integration into existing service provider and service access point infrastructures. Special emphasis is put on privacy policies that can be configured by users themselves, and distinguishing between the initial data access phase and the later data usage control phase. We also discuss the challenges of practically applying the required changes to real-world infrastructures, including delegated administration, monitoring, and auditing.

A Security Prioritized Computational Grid Scheduling Model

Grid supports heterogeneities of resources in terms of security and computational power. Applications with stringent security requirement introduce challenging concerns when executed on the grid resources. Though grid scheduler considers the computational heterogeneity while making scheduling decisions, little is done to address their security heterogeneity. This work proposes a security aware computational grid scheduling model, which schedules the tasks taking into account both kinds of heterogeneities. The approach is known as Security Prioritized MinMin (SPMinMin). Comparing it with one of the widely used grid scheduling algorithm MinMin (secured) shows that SPMinMin performs better and sometimes behaves similar to MinMin under all possible situations in terms of makespan and system utilization.

Porting HPC Applications to Grids and Clouds

A Grid enables remote, secure access to a set of distributed, networked computing and data resources. Clouds are a natural complement to Grids towards the provisioning of IT as a service. To “Grid-enable” applications, users have to cope with: complexity of Grid infrastructure; heterogeneous compute and data nodes; wide spectrum of Grid middleware tools and services; the e-science application architectures, algorithms and programs. For clouds, on the other hand, users don’t have many possibilities to adjust their application to an underlying cloud architecture, because of its transparency to the user. Therefore, the aim of this chapter is to guide users through the important stages of implementing HPC applications on Grid and cloud infrastructures, together with a discussion of important challenges and their potential solutions. As a case study for Grids, we present the Distributed European Infrastructure for Supercomputing Applications (DEISA) and describe the DEISA Extreme Computing Initiative (DECI) for porting and running scientific grand challenge applications on the DEISA Grid. For clouds, we present several case studies of HPC applications running on Amazon’s Elastic Compute Cloud EC2 and its recent Cluster Compute Instances for HPC. This chapter concludes with the author’s top ten rules of building sustainable Grid and cloud e-infrastructures.

A Replica Based Co-Scheduler (RBS) for Fault Tolerant Computational Grid

Grid is a parallel and distributed computing network system comprising of heterogeneous computing resources spread over multiple administrative domains that offers high throughput computing. Since the Grid operates at a large scale, there is always a possibility of failure ranging from hardware to software. The penalty paid of these failures may be on a very large scale. System needs to be tolerant to various possible failures which, in spite of many precautions, are bound to happen. Replication is a strategy often used to introduce fault tolerance in the system to ensure successful execution of the job, even when some of the computational resources fail. Though replication incurs a heavy cost, a selective degree of replication can offer a good compromise between the performance and the cost. This chapter proposes a co-scheduler that can be integrated with main scheduler for the execution of the jobs submitted to computational Grid. The main scheduler may have any performance optimization criteria; the integration of co-scheduler will be an added advantage towards fault tolerance. The chapter evaluates the performance of the co-scheduler with the main scheduler designed to minimize the turnaround time of a modular job by introducing module replication to counter the effects of node failures in a Grid. Simulation study reveals that the model works well under various conditions resulting in a graceful degradation of the scheduler’s performance with improving the overall reliability offered to the job.

Distributed Dynamic Load Balancing in P2P Grid Systems

P2P Grids could solve large-scale scientific problems by using geographically distributed heterogeneous resources. However, a number of major technical obstacles must be overcome before this potential can be realized. One critical problem to improve the effective utilization of P2P Grids is the efficient load balancing. This chapter addresses the above-mentioned problem by using a distributed load balancing policy. In this chapter, we propose a P2P communication mechanism, which is built to deliver varied information across heterogeneous Grid systems. Basing on this P2P communication mechanism, we develop a load balancing policy for improving the utilization of distributed computing resources. We also develop a P2P resource monitoring system to capture the dynamic resource information for the decision making of load balancing. Moreover, experimental results show that the proposed load balancing policy indeed improves the utilization and achieves effective load balancing.

Trusted Data Management for Grid-Based Medical Applications

Existing Grid technology has been foremost designed with performance and scalability in mind. When using Grid infrastructure for medical applications, privacy and security considerations become paramount. Privacy aspects require a re-thinking of the design and implementation of common Grid middleware components. This chapter describes a novel security framework for handling privacy sensitive information on the Grid, and describes the privacy and security considerations which impacted its design.

Identifying Secure Mobile Grid Use Cases

Mobile Grid includes the characteristics of the Grid systems together with the peculiarities of Mobile Computing, with the additional feature of supporting mobile users and resources in a seamless, transparent, secure, and efficient way. Security of these systems, due to their distributed and open nature, is considered a topic of great interest. We are elaborating a process of development to build secure mobile Grid systems considering security on all life cycles. In this chapter, we present the practical results applying our development process to a real case, specifically we apply the part of security requirements analysis to obtain and identify security requirements of a specific application following a set of tasks defined for helping us in the definition, identification, and specification of the security requirements on our case study. The process will help us to build a secure Grid application in a systematic and iterative way.