Paul D. Manuel

Trust management system for grid and cloud resources

Trust plays an important role in all commercial grid and cloud environments. It is the estimation of competence of a resource provider in completing a task based on reliability, security, capability and availability in the context of distributed environment. It enables users to select the best resources in the heterogeneous grid and cloud infrastructure. This paper introduces a novel trust model to evaluate the grid and cloud resources by means of resource broker. The resource broker chooses appropriate grid/cloud resource in heterogeneous environment based on the requirements of user. Our proposed trust management system is implemented with Kerberos authentication and PERMIS (PrivilEge and Role Management Infrastructure Standard) authorization to enhance the trust of the broker itself. The proposed trust enhanced resource broker evaluates the trust value of the resources based on the identity as well as behavioral trust. The proposed model considers metrics suitable for both grid and cloud resources. The results of the experiments show that the proposed model selects the dependable and reliable resources in grid and cloud environment.

Exact wirelength of hypercubes on a grid

Grid embeddings are used not only to study the simulation capabilities of a parallel architecture but also to design its VLSI layout. In addition to dilation and congestion, wirelength is an important measure of an embedding. There are very few papers in the literature which provide the exact wirelength of grid embedding. As far as the most versatile architecture hypercube is concerned, only approximate estimates of the wirelength of grid embedding are available. In this paper, we give an exact formula of minimum wirelength of hypercube layout into grids and thereby we solve completely the wirelength problem of hypercubes into grids. We introduce a new technique to estimate the wirelength of a grid embedding. This new technique is based on a Congestion Lemma and a Partition Lemma which we study in this paper.

A perishable inventory system with service facilities and retrial customers

In this article, we present a continuous review perishable (s, S) inventory system with a service facility consisting of finite waiting room and a single server. The customers arrive according to a Markovian arrival process (MAP). The individual customers unit demand is satisfied after a random time of service which is assumed to have phase-type distribution. The life time of each item and the lead time of reorders are assumed to have independent exponential distributions. Any arriving customer, who finds the waiting room is full, enters into the orbit of infinite space. These orbiting customers compete for service by sending out signals the duration between two successive attempts are exponentially distributed. The joint probability distribution of the number of customers in the waiting room, number of customers in the orbit and the inventory level is obtained in the steady-state case. Various stationary system performance measures are computed and total expected cost rate is calculated.

An efficient representation of Benes networks and its applications

The most popular bounded-degree derivative network of the hypercube is the butterfly network. The Benes network consists of back-to-back butterflies. There exist a number of topological representations that are used to describe butterfly-like architectures. We identify a new topological representation of butterfly and Benes networks. The minimum metric dimension problem is to find a minimum set of vertices of a graph G(V,E) such that for every pair of vertices u and v of G, there exists a vertex w with the condition that the length of a shortest path from u to w is different from the length of a shortest path from v to w. It is NP-hard in the general sense. We show that it remains NP-hard for bipartite graphs. The algorithmic complexity status of this NP-hard problem is not known for butterfly and Benes networks, which are subclasses of bipartite graphs. By using the proposed new representations, we solve the minimum metric dimension problem for butterfly and Benes networks. The minimum metric dimension problem is important in areas such as robot navigation in space applications.

Embedding of cycles and wheels into arbitrary trees

We estimate and characterize the edge congestion-sum measure for embeddings of various graphs such as cycles, wheels, and generalized wheels into arbitrary trees. All embedding algorithms apply an interesting general technique based on the consecutive label property. Our algorithms produce optimal values of sum of dilations and sum of edge-congestions in linear time.

Adaptive checkpointing strategy to tolerate faults in economy based grid

In this paper, we develop a fault tolerant job scheduling strategy in order to tolerate faults gracefully in an economy based grid environment. We propose a novel adaptive task checkpointing based fault tolerant job scheduling strategy for an economy based grid. The proposed strategy maintains a fault index of grid resources. It dynamically updates the fault index based on successful or unsuccessful completion of an assigned task. Whenever a grid resource broker has tasks to schedule on grid resources, it makes use of the fault index from the fault tolerant schedule manager in addition to using a time optimization heuristic. While scheduling a grid job on a grid resource, the resource broker uses fault index to apply different intensity of task checkpointing (inserting checkpoints in a task at different intervals).To simulate and evaluate the performance of the proposed strategy, this paper enhances the GridSim Toolkit-4.0 to exhibit fault tolerance related behavior. We also compare “checkpointing fault tolerant job scheduling strategy” with the well-known time optimization heuristic in an economy based grid environment. From the measured results, we conclude that even in the presence of faults, the proposed strategy effectively schedules grid jobs tolerating faults gracefully and executes more jobs successfully within the specified deadline and allotted budget. It also improves the overall execution time and minimizes the execution cost of grid jobs.

Embedding hypercubes into cylinders, snakes and caterpillars for minimizing wirelength

We consider the problem of embedding hypercubes into cylinders to minimize the wirelength. Further, we show that the edge isoperimetric problem solves the wirelength problem of regular graphs and, in particular, hypercubes into triangular snakes and caterpillars.

Embeddings of circulant networks

In this paper we solve the edge isoperimetric problem for circulant networks and consider the problem of embedding circulant networks into various graphs such as arbitrary trees, cycles, certain multicyclic graphs and ladders to yield the minimum wirelength.

Landmarks in torus networks

Abstract A minimum metric basis is a minimum set M of vertices of a graph G(V, E) such that for every pair of vertices u and v of V\M, there exists a vertex w∈M with the condition that the length of a shortest path from u to w is different from the length of a shortest path from v to w. In this paper we study the minimum metric dimension problem for torus networks. We prove that for torus TR(m, n), m≤n, the minimum metric dimension is 3 when at least one of m or n is odd. We provide an upper bound for the minimum metric dimension when both m and n are even.

A data-centric design for n-tier architecture

The increasing heterogeneity, complexity, and distributed nature of deployment architectures only serve to compound the problems faced by software solutions. With the advent of the Internet and web technologies, system designers have had to reevaluate the applicability of n-tier architectures, and assess which technologies are appropriate at each tier. In this paper we evaluate the design issues of n-tier architecture. We debate whether it is good to move code or data to communicate messages between applications. Based on the latest technology of J2EE and .NET framework, we recommend a data centric design of n-tier architecture. Based on our experience we also suggest a modified interactive software process model.