Jinyuan You

An RBAC Based Policy Enforcement Coordination Model in Internet Environment

An RBAC (Role Based Access Control) based and policy enforcement coordination (RBPEC) model suitable in Internet environment is described. Coordination deals with the interaction between different agents and also between agents and surrounding environments. A set of agents interacting with each other for a common global system task constitutes a coordination group. Coordination is combined with access control in RBPEC model. Role based access control is introduced for security concerns. Coordination policy is enforced in a distributed manner. The model has two advantages of being secure and scalable.

Main sequences genetic scheduling for multiprocessor systems using task duplication

Abstract This paper addresses the problem of scheduling parallel program tasks onto multiprocessors to minimize its execution time. The scheduling problem is known to be NP-complete, whether task duplication is used or not. To overcome the weakness of the existing genetic scheduling algorithms, a novel chromosome encoding scheme is adopted in the proposed scheduling algorithms. Moreover, the knowledge of the main sequences (MSs) in a task graph is integrated into the proposed algorithm to improve its performance. We compare the TOK algorithm proposed by Tsuchiya et al. with our proposed algorithms in terms of schedule length and running time to find the schedule. Experimental results show the effectiveness of main sequences genetic scheduling algorithm.

DTuples: A Distributed Hash Table based Tuple Space Service for Distributed Coordination

In this paper, we introduce a Linda (Carriero et al., 1989) like peer-to-peer tuple space middleware build on top of distributed hash table Tuples. With the help of DTuples, the development of the distributed cooperation and coordination task would be simplified. The decoupled style of tuple space (Carriero and Gelemter, 2001) model is useful in peer-to-peer environment. In the application level, the DTuples was used instead of the publish/subscribe model and message-passing model. In low level, the DTuples service can be used as cooperation middleware and context-aware middleware. The tuples in the DTuples are stored in distributed hash table based peer-to-peer tuple storage. In our current work, the in(), rd(), out() and copy-collect() primitives are supported. The eval() primitive will be added to D-Tuples in the future. In this paper, we present the key design concepts of DTuples

Random walk search in unstructured P2P

Unstructured P2P has power-law link distribution, and the random walk in power-law networks is analyzed. The analysis results show that the probability that a random walker walks through the high degree nodes is high in the power-law network, and the information on the high degree nodes can be easily found through random walk. Random walk spread and random walk search method (RWSS) is proposed based on the analysis result. Simulation results show that RWSS achieves high success rates at low cost and is robust to high degree node failure.

An Intelligent System Based On Adaptive CTBN For Uncertainty Reasoning In Sensor Networks

Abstract ;onsisting of various sensing and computing devices deployed in a changing environrnent, a sensor network’s raw sensed data have many uncertainties. A natural way to deal with them is generating belief messages. Sensing objects continuously change with time, so are their beliefs. Therefore, dynamic models are required to monitor distributed states in the system. This paper presents a CTBN based intelligent system for modeling dynamics and processing uncertainties in sensor networks. Algorithms for message passing and parameter updating for adapting the model to the changing environrnent are provided. The effectiveness of the system is shown in experiments.

Group mobility model in mobile peer-to-peer media streaming system

Topological dynamics of mobile peer-to-peer are exacerbated by the changes of mobile users location and interest. We observe that the velocity representation of mobile nodes provides a characterization of the mobility groups. We attempt to predict the future availability of wireless links based on group mobility model. Intuitively, mobile peers within the same group tend to have a high probability of keeping stable interconnection topology. We use the velocity-group model, which helps us predict the future availability of wireless links and leads to fast amplifying the systems total streaming capacity using its self-growing. The extensive simulation results show the efficiency of the proposed model in mobile peer-to-peer media streaming system.

Genetic Scheduling on Minimal Processing Elements in the Grid

This paper addresses the problem of scheduling parallel program tasks onto computational grid to minimize the execution time of the parallel program and the number of required processing elements. This task scheduling problem is known to be NP-complete. Existing scheduling algorithms either assume a fixed number of processing elements, or generate schedules that need more processing elements than necessary, which is especially obvious when using task duplication technique. To overcome the weaknesses, we propose a genetic scheduling algorithm using task duplication. The proposed algorithm can yield schedules with shorter execution time and fewer required processing elements, and without useless task duplications. The conditions under which the algorithm performs best were highlighted.

Network-aware multicasting for video-on-demand services

In this paper, we propose a network-aware multicast scheme to supply instantaneous VOD (video-on-demand) services. Being different from traditional VOD systems, this system is implemented based on peer-to-peer grid. By taking advantage of the large storage and the powerful processing capability in client-side devices, the user host serves as both a client and a non-dedicated video server. The system capability is enhanced due to the contribution of user hosts. Peer groups are formed as a collection of peers that share similar interest, and workload may be fairly apportioned among autonomous groups. In this VOD system, the adaptive video delivery mainly employs a new dynamic buffering algorithm and an improved video multicast strategy to achieve an optimal utilization of system resources, and the network-aware adaptation makes the system more robust. In cooperating with each other, the relevant servers can supply instantaneous video services for local users.

Stable group model in mobile peer-to-peer media streaming system

We study two key problems arising from mobile peer-to-peer media streaming: the stability of interconnection between supplying peers and requesting peers in the mobile peer-to-peer streaming system; and fast capacity amplification of the entire mobile peer-to-peer streaming system. Many algorithms for the fast capacity amplification of the peer-to-peer streaming system have been proposed. However, these algorithms are inefficient in the mobile ad-hoc networks. Topological dynamics of mobile peer-to-peer are exacerbated by the changes of mobile users location and interest. We observe that the mobile users exhibit correlated mobility patterns in practical ad-hoc networks. We use the stable group algorithm to characterize user mobility in mobile ad-hoc networks. Based on the stable group, we then propose a distributed stable-group differentiated admission control algorithm (SGDAC/sub p2p/), which leads to fast amplifying of the systems total streaming capacity using self-growing. Finally, extensive simulation results are presented to compare between the SGDAC/sub p2p/ and traditional methods to prove the superiority of the algorithm.

The Delivery and Accounting Middleware in the ShanghaiGrid

The ShanghaiGrid is a Grid Computing Environment (GCE) being under construction based on the Grid Service standards and technologies in Open Grid Services Architecture (OGSA). The primary motivation of the grid is to build a general, shared Information Grid Platform and to terminate the history of the case-by-case designing pattern in the development of grids. In this paper, we give a brief introduction to the concept, infrastructure, and key technologies of the ShanghaiGrid. Particularly, we focus on the introduction of the Grid Services Delivery Toolkit and the Grid Accounting Toolkit, which play an important role in the ShanghaiGrid as Grid middleware.