SungJin Choi’s research while affiliated with Samsung Sdi Co., Ltd. and other places

Mobile grid is a branch of grid computing that incorporates mobile devices into the grid infrastructure. It poses new challenges because mobile devices are typically resource-constrained and exhibit unique characteristics such as instability in network connections. New scheduling strategies are imperative in mobile grid to efficiently utilize the devices. This paper presents a scheduling algorithm that considers dynamic properties of mobile devices such as availability, reliability, maintainability, and usage pattern in mobile grid environments. In particular, usage patterns caused by voluntarily or involuntarily losing a connection, such as switching off the device or a network interruption could be important criteria for choosing the best resource to execute a job. The experimental results show that our scheduling algorithm provides superior performance in terms of execution time, as compared to the other methods that do not consider usage pattern. Throughout the experiments, we found it essential to consider usage pattern for improving performance in the mobile grid.

The emerging Grid is extending the scope of resources to mobile devices and sensors that are connected through loosely connected networks. Nowadays, the number of mobile device users is increasing dramatically and the mobile devices provide various capabilities such as location awareness that are not normally incorporated in fixed Grid resources. Nevertheless, mobile devices exhibit inferior characteristics such as poor performance, limited battery life, and unreliable communication, compared with fixed Grid resources. Especially, the intermittent disconnection from network owing to users’ movements adversely affects performance, and this characteristic makes it inefficient and troublesome to adopt the synchronous message delivery in mobile Grid. This paper presents a mobile Grid system architecture based on mobile agents that support the location management and the asynchronous message delivery in a multi-domain proxy environment. We propose a novel balanced scheduling algorithm that takes users’ mobility into account in scheduling. We analyzed users mobility patterns to quantitatively measure the resource availability, which is classified into three types: full availability, partial availability, and unavailability. We also propose an adaptive load-balancing technique by classifying mobile devices into nine groups depending on availability and by utilizing adaptability based on the multi-level feedback queue to handle the job type change. The experimental results show that our scheduling algorithm provides a superior performance in terms of execution times to the one without considering mobility and adaptive load-balancing.

Mobile Grid is a branch of Grid where the infrastructure includes mobile devices. The mobile Grid exhibits different challenges such as resource-constraints and users’ movements, compared to the traditional Grid. Mobile agent is an attractive technology to overcome these challenges. In this paper, we present a new mobile Grid system based on the mobile agent. This paper describes the architecture of the new system: multi-proxy based mobile grid environment with location management and message delivery mechanism. Our system is lightweight enough to be installed on mobile devices. It also provides the physical and logical mobility of mobile agents. We implemented the mobile Grid system based on Globus Toolkit and ODDUGI mobile agent system. Keywordsmobile Grid-mobile agent-mobility

Mobile Grid is a branch of Grid computing where the infrastructure includes mobile devices. Because mobile devices are resource-constrained, mobile Grid should provide new scheduling strategies considering its environment. This paper presents a group-based fault tolerance scheduling algorithm. The algorithm classifies mobile devices into several groups considering characteristic parameters of mobile Grid. Then, it uses an adaptive replication algorithm for enduring faults in an active manner. The experimental results show that our scheduling algorithm provides a superior performance in terms of execution times to the one without considering grouping and fault tolerance. Throughout the experiments, we found that the active fault tolerance (i.e., replication) is essential to improving performance in mobile Grid. Keywordsmobile Grid-scheduling algorithm-replication

Hybrid Peer-to-Peer (P2P) systems that construct overlay networks structured among superpeers have great potential in that they can give the benefits such as scalability, search speed and network traffic, taking advantages of superpeer-based and the structured P2P systems. In this article, we enhance keyword search in hybrid P2P systems by constructing a tree-based index overlay among directory nodes that maintain indices, according to the load and popularity of a keyword. The mathematical analysis shows that the keyword search based on semi-structured P2P overlay can improve the search performance, reducing the message traffic and maintenance costs. Keywordstree-based index overlay-keyword search-fault-tolerance-performance

A mobile agent system is regarded as an attractive technology when developing distributed applications. However, mobility makes it more difficult to trace agents. It is also more complex for agents to communicate with each other in a reliable manner. Therefore, a reliable communication protocol is necessary to control and monitor mobile agents and deliver messages between them. In this paper, a new reliable communication protocol (RCP) is proposed for a multiregion mobile agent computing environment. RCP is implemented on the ODDUGI mobile agent system. Analysis and evaluation show that RCP fulfills the following design goals: reliability, asynchrony, timeliness, location dependency, scalability, and communication cost.

The recent tendency of transfer from centralized desktop to P2P desktop grids requires redesigning the result verification mechanism that has been developed for the former. Since there is no central server to verify the correctness of task results in P2P desktop grids, it is difficult to intactly apply the existing mechanisms to P2P environments. In this paper, we propose a result verification mechanism based on a task tree that can efficiently provide the result correctness against malicious resources in P2P desktop grids. In the mechanism, a task tree is built based on the availability and reputation of resources, and different result verification methods are used according to level characteristics in the task tree. Numerical analysis results show that our mechanism performs better than the existing ones, in terms of the correctness of task results.

A mobile agent is regarded as an attractive technology when developing distributed applications in mobile and ubiquitous comput- ing environments. In this paper, we present ODDUGI, a java-based ubiquitous mobile agent system. The ODDUGI mobile agent system provides fault tolerance, security, location management and message delivery mechanisms in a multi-region mobile agent computing environ- ment. We describe the architecture, design concepts and main features of the ODDUGI. In addition, we present the One-Touch Campus Service application developed on the basis of ODDUGI in mobile and ubiquitous computing environments.

This chapter reviews dynamism in desktop Grid computing and explains the advanced stochastic scheduling scheme with the Markov Job Scheduler based on Availability (MJSA) in the environment. In recent years, Grid computing [1] has received considerable interest in the field of academics and enterprise. Numerous attempts have been made to organize cost efficient large-scale Grid computing. Desktop Grid computing [13,19,2] is a more flexible paradigm that is used to achieve high performance and high throughput with desktop resources that are less stable and has more inferior performance compared to traditional Grid. It is comprised of a diverse set of desktops interconnected with various network forms ranging from Local Area Network (LAN) to the Internet. Desktop Grid system has played a leading role in the development of large scale aggregated computing power harvested from the edge of the Internet at lower cost. The main goals of the system are to accomplish high throughput and performance by mobilizing the potential colossal computational resources of idle desktops. However, since a desktop peer is a fluctuating resource that connects to the system, performs computations and disconnects to the network at will, desktop volatility makes the system unstable and unreliable. To develop a reliable desktop Grid computing system, a scheduling scheme must consider the dynamic nature (i.e., volatility) of volunteers and a resource selection scheme should adapt to such a dynamic environment, as the selection is getting complicated due to the uncertain behavior of desktops. This chapter demonstrates desktop state change modelling and an advanced resource selection scheme, Selection of Credible Resource with Elastic Window (SCREW), to choose reliable resources in dynamic computational desktop Grid environments. Markov modelling of the dynamic state turning provides understanding of the pattern of desktop behavior while SCREW selects qualified desktops that satisfy time requirements to complete given workloads and adapts to the needs of the user and the application on the fly.

Although desktop Grid computing has been regarded as a cost-efficient computing paradigm, the system has suffered from scalability issues caused by its centralized structure. In addition, resource volatility generates system instability and performance deterioration. However, regarding the provision of a reliable and stable execution environment, resource management becomes more intricate when the system is constructed in a fully decentralized fashion without a central server. Scaling the system numerically and geographically is necessary for autonomous network organization, facile adaptation to execution failure and dynamic self-management of volatile resources. In order to develop a fully decentralized desktop Grid computing system securely, we propose an autonomous desktop Grid computing system, Self-Gridron based on a neural overlay network. Self- Gridron supports reliable, autonomous, and cost-effective scheduling which includes eligible resource classification and job management (i.e. allocation, replication, and reassignment). Furthermore, Self-Gridron provides sovereign learning with error correction) and evolves adaptively by itself to system changes or failure on the fly while improving performance.