SungJin Choi

Characterizing and Classifying Desktop Grid

Desktop Grid has recently received the strong attraction for executing high throughput applications as CPU, storage and network capacities improve and become cheaper. Desktop Grid is different from Grid in many respects, but there is no general survey or taxonomy for desktop Grid. Therefore, we propose a new comprehensive taxonomy and survey of desktop Grid in order to characterize and categorize desktop Grid.

MJSA: Markov job scheduler based on availability in desktop grid computing environment

In a desktop grid computing environment, voluntary desktops (i.e., resource providers) are free to leave and join independently in the middle of execution. To develop a reliable desktop grid computing system, a scheduling scheme must consider the dynamic nature (i.e., volatility) of volunteers. Existing desktop grid computing systems, however, do not consider volatility in their scheduling procedures. As a result, job execution is often suspended, resulting in delayed completion time and degraded performance and reliability. To solve these limitations, we propose the Markov Job Scheduler based on Availability (MJSA) supporting three advanced scheduling schemes: OPTIMIST, PESSIMIST, and REALIST. These scheduling schemes are based on stochastic modeling of desktop availability. In the OPTIMIST scheme, in which time constraints are relaxed, the MJSA provides reliable resource selection at low cost. In the PESSIMIST scheme, where time constraints are rigid, the MJSA enables stable makespan in strictly time. Finally, in the REALIST scheme, where time constraints are only partially relaxed, the MJSA provides enhanced cost efficiency. In conclusion, the MJSA improves performance and reliability by adapting the appropriate scheduling scheme when selecting volunteers according to the needs of applications.

Adaptive group scheduling mechanism using mobile agents in peer-to-peer grid computing environment

Peer-to-peer grid computing is an attractive computing paradigm for high throughput applications. However, both volatility due to the autonomy of volunteers (i.e., resource providers) and the heterogeneous properties of volunteers are challenging problems in the scheduling procedure. Therefore, it is necessary to develop a scheduling mechanism that adapts to a dynamic peer-to-peer grid computing environment. In this paper, we propose a Mobile Agent based Adaptive Group Scheduling Mechanism (MAAGSM). The MAAGSM classifies and constructs volunteer groups to perform a scheduling mechanism according to the properties of volunteers such as volunteer autonomy failures, volunteer availability, and volunteering service time. In addition, the MAAGSM exploits a mobile agent technology to adaptively conduct various scheduling, fault tolerance, and replication algorithms suitable for each volunteer group. Furthermore, we demonstrate that the MAAGSM improves performance by evaluating the scheduling mechanism in Korea@Home.

Group-based dynamic computational replication mechanism in peer-to-peer grid computing

A peer-to-peer grid computing is complicated by heterogeneous capabilities, failures, volatility, and lack of trust because it is based on desktop computers at the edge of the Internet. In order to improve the reliability of computation and gain better performance, a replication mechanism must adapt to these distinct features. In other words, it is required to classify volunteers into groups that have similar properties and then dynamically apply different replication algorithms to each group. However, existing mechanisms do not provide such a replication mechanism on a per group basis. As a result, they cause a high overhead and poor performance. To solve the problems, we propose a new group-based computational replication mechanism to adapt to an unstable, untrusted, dynamic peer-to-peer grid computing environment. Our mechanism can reduce the number of redundancy and therefore complete many tasks by adaptively replicating computations on the basis of the properties of volunteer group such as availability, credibility, and volunteering service time.

Reliable Asynchronous Message Delivery for Mobile Agents

Agents mobility makes it difficult for them to deliver messages reliably, but a new system could change that. To asynchronously deliver messages to a mobile agent, the reliable asynchronous message delivery (RAMD) protocol places a blackboard in each region server for sharing information. RAMD also relates message delivery with a mobile agents migration, thus addressing the tracking and message-delivery problems

Scheduling Scheme based on Dedication Rate in Volunteer Computing Environment

A volunteer node can join and leave a volunteer computing system freely. However, existing volunteer computing systems suffer from interruptions of job execution, delays of execution time, and increases of total execution time, since they do not consider dynamic scheduling properties (i.e. volatilities), such as leave, join, and suspension. Therefore, dynamic execution properties of volunteer node should be considered in scheduling schemes, in order to design a stable and reliable volunteer computing system. This paper proposes a new scheduling scheme based on the dedication rate (DR), which reflects the dynamic properties of a volunteer. The scheduling scheme improves the completeness and reliability of execution, while also decreasing delay and total execution time. In addition, an implementation of the proposed scheduling scheme on top of Korea@Home is described, as well as performance evaluation

Advanced Job Scheduler Based on Markov Availability Model and Resource Selection in Desktop Grid Computing Environment

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.

Multi-Node Global Directory Construction in Peer-to-Peer Systems

In P2P systems, the speed of searching for desired lists of sharable files is one of the most important measurement issues in evaluation of overall system performance. Although the searching schemes of existing non-structured P2P systems have been improved to enhance speed considerably, they still never reach to the level of those of the centralized and structured systems. In this paper, we propose a multi-node global directory in P2P systems, where all the lists of sharable resources of the joining peers are aggregated and divided into the chosen nodes while keeping collating sequence as a whole to make one big linked list. Thus in indexed sequential searching, the system provides us with convenience of using the command like dir of MS-DOS, and in general keyword searching, which is naturally impossible for the structured P2P systems, the searching speed is even faster than those of centralized P2P systems since a small list segment is scanned at each node synchronously in parallel

A Peer to Peer Grid Computing System Based on Mobile Agents

In a peer to peer grid computing system, volunteers (i.e., resource provides) with heterogeneous properties can freely join and leave in the middle of their computation. Thus, the system should be adaptive to a dynamic changing environment. In particular, scheduling, result certification, and replication mechanisms must be dynamic and adaptive in such a system. In this paper, we propose a new peer to peer grid computing system based on mobile agents. The proposed system constructs volunteer groups according to volunteers dynamic properties such as service time, availability, and credibility. For each volunteer groups, different scheduling, result certification, replication mechanisms are used. These mechanisms are implemented as mobile agents and are conducted in a decentralized way.

Result Verification Mechanism Based on Availability and Reputation of Resources in P2P Desktop Grid Systems

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.