Trieu C. Chieu

Dynamic Scaling of Web Applications in a Virtualized Cloud Computing Environment

Scalability is critical to the success of many enterprises currently involved in doing business on the web and in providing information that may vary drastically from one time to another. Maintaining sufficient resources just to meet peak requirements can be costly. Cloud computing provides a powerful computing model that allows users to access resources on-demand. In this paper, we will describe a novel architecture for the dynamic scaling of web applications based on thresholds in a virtualized Cloud Computing environment. We will illustrate our scaling approach with a front-end load-balancer for routing and balancing user requests to web applications deployed on web servers installed in virtual machine instances. A dynamic scaling algorithm for automated provisioning of virtual machine resources based on threshold number of active sessions will be introduced. The on-demand capability of the Cloud to rapidly provision and dynamically allocate resources to users will be discussed. Our work has demonstrated the compelling benefits of the Cloud which is capable of handling sudden load surges, delivering IT resources on-demands to users, and maintaining higher resource utilization, thus reducing infrastructure and management costs.

Depolarization field and ionic effects on the bistability of surface‐stabilized ferroelectric liquid‐crystal devices

Based on a collective switching model coupled to a simplified continuity equation for impurity ions, the internal electric field and light transmission of a surface‐stabilized (SS), layer‐tilted ferroelectric liquid‐crystal (FLC) cell with insulating alignment layers have been calculated as a function of time, under bipolar voltage pulses. The polarization and ionic charges, accumulated on the interfaces between the FLC medium and alignment layers, tend to partially screen the external on‐field and generate a depolarization field to reverse the spontaneous polarization when the external field is off. When the thickness of the alignment layer is greater than 1000 A, it is difficult to achieve bistability using FLC mixtures with a spontaneous polarization larger than approximately 20 nC/cm2. For bistability to occur in a SSFLC cell with high spontaneous polarization, thin insulating or conducting alignment layers are preferred. We also found that the existence of impurity ions in a SSFLC cell is always detr...

An intelligent event adaptation mechanism for business performance monitoring

Business performance monitoring is to observe, analyze, and possibly control the execution of business operations. Often in the information technology implementation environment, dynamic events are generated to indicate the states of the business processes. These isolated and heterogeneous low-level events create needs for adaptation and standardization, before the events can be handled by a central mediation engine, which fillers, sorts and correlates events into key performance indicators relating to business goals. In this paper, we propose an intelligent event adaptation mechanism for capturing, analyzing, enriching and transforming application-dependent IT-level events into a standard event format called the common base event. The resulting event adapter can capture and process low-level events and forward only business related events to the central mediation engine. We select the SAP system as a reference application, and illustrate the configuration issues between the application and its adapter. The architecture and functionality of the proposed event adaptation mechanism are explained with practical industry problems and scenarios

Secure Search of Private Documents in an Enterprise Content Management System

An enterprise content management system such as an electronic contract system manages a large number of secure documents for many organizations. The search of these private documents for different organizational users with role- based access control is a challenging task. In this paper, we present a novel content-based XML-annotated secure-index search mechanism that provides an effective search and retrieval of private documents with document-level security. The search mechanism includes a document analysis framework for text analysis and annotation, a search indexer to build and incorporate document access control information directly into a search index, an XML-based search engine, and a compound query generation technique to join user role and organization information into search query. Our experiments on a pilot electronic contract system demonstrate that, by incorporating document access information directly into the search index and combining user information in the search query, search and retrieval of private contract documents can be achieved very effectively and securely with high performance.

Solution-based deployment of complex application services on a Cloud

Managing and containing runaway IT costs for solution deployment is one of the top priorities for enterprises. Cloud Computing, with its on-demand provisioning capability on shared resources, has emerged as a new paradigm for reducing IT costs. In this paper, we describe a solution-based provisioning mechanism to automate the deployment of complex application services on a Cloud infrastructure. We introduce the concept of Composite Appliance and show how it can be used to deploy a complete solution and to simplify management tasks. We illustrate the advantages of our approach with a prototype solution consisting of two-tier application services that are deployed and configured automatically on virtual machine instances without manual intervention.

Ranking and mapping of applications to cloud computing services by SVD

Cloud computing promises to provide high performance, on-demand services in a flexible and affordable manner, it offers the benefits of fast and easy deployment, scalability and service oriented architecture. It promises substantial cost reduction together with increased flexibility than the traditional IT operation. Cloud service providers typically come with various levels of services and performance characteristics. In addition, there are different types of user applications with specific requirements such as availability, security and computational power. Currently, there are no standard ranking and classification services for the users to select the appropriate providers to fit their application requirements. Determining the best cloud computing service for a specific application is a challenge and often determines the success of the underlying business of the service consumers. In this paper, we propose a set of cloud computing specific performance and quality of service (QoS) attributes, an information collection mechanism and the analytic algorithm based on Singular Value Decomposition Technique (SVD) to determine the best service provider for a user application with a specific set of requirements. This technique provides an automatic best-fit procedure which does not require a formal knowledge model.

Scalability and Performance of Web Applications in a Compute Cloud

Scalability and performance are key factors to the success of many enterprises involved in doing business on the web. Maintaining sufficient web resources just to meet performance during peak demands can be costly. Compute Cloud provides a powerful environment to allow dynamic scaling of web applications without the needs for user intervention. In this paper, we present a case study on the scalability and performance of web applications in a Cloud. We describe a novel dynamic scaling architecture with a front-end load-balancer for routing user requests to web applications deployed on virtual machine instances with the goal of maximizing resource utilization in instances while minimizing total number of instances. A scaling algorithm for automated provisioning of virtual resources based on threshold number of active user sessions will be introduced. The on-demand capability of the Cloud to rapidly provision and dynamically allocate resources to users will be discussed. Our work has demonstrated the compelling benefits of a Cloud which is capable of sustaining performance upon sudden load surges, delivering satisfactory IT resources on-demands to users, and maintaining high resource utilization, thus reducing infrastructure and management costs.

Transport properties of ions in ferroelectric liquid crystal cells

The transient ionic current in a ferroelectric liquid crystal (FLC) cell was measured as a function of applied voltage at different temperatures. The measured current shows a delay peak which decays rapidly to a steady-state value. The steady-state current exhibits a thermal activated behavior with an activation energy of 0.94 eV, and depends exponentially on the square root of the field strength similar to the Schottky effect. To describe the transport behaviors of the ions, a model with ionization-recombination equations which include a field-dependent ionization coefficient, and a continuity equation for the accumulated surface charges has been introduced. According to the model, the current decay time and the peak position of the delay peak current can be used to determine the ion mobility. Two ionized species have been identified in the FLC medium: a weakly ionized species with a relatively constant mobility of 2.0×10-7 cm2/Vs, and a highly ionized species with a room temperature mobility of 4.1×10-7 cm2/Vs and a thermal activation energy of about 0.71 eV. Detailed calculation of the ionic current and comparison with experimental results are given.

Dynamic Resource Allocation via Distributed Decisions in Cloud Environment

The adaptation of virtualization technologies and the Cloud Compute model by Web service providers is accelerating. These technologies commonly known as Cloud Compute Model are built upon an efficient and reliable dynamic resource allocation system. Maintaining sufficient resources to meet peak workloads while minimizing cost determines to a large extend the profitability of a Cloud service provider. Traditional centralized approach of resource provisioning with global optimization and statistical strategies can be complex, difficult to scale, computational intensive and often non-traceable which adds to the cost and efficiency of Cloud operation, especially in industrial environments. As we have learned in real life, the most efficient economic system is the one that provides individuals with incentives for their own decisions. It is also true for computing systems. In this paper, we present an architecture for dynamic resource provisioning via distributed decisions. We will illustrate our approach with a Cloud based scenario, in which each physical resource makes its own utilization decision based on its own current system and workload characteristics, and a light-weight provisioning optimizer with a replaceable routing algorithm for resource provisioning and scaling. This approach enables resource provisioning system to be more scalable, reliable, traceable, and simple to manage. In an industrial setting, the importance of these characteristics often exceeds the goal of squeezing the absolute last CPU cycles of the underlying physical resources.

Autonomic Ranking and Selection of Web Services by Using Single Value Decomposition Technique

With the proliferation of Web services as a business solution to enterprise application integration, ranking and selecting the best Web services among the providers become an important factor in the success of the business solution. Quality of service (QoS) determines the quality and usability of a service including its price, performance, reliability, integrity, accessibility, availability, interoperability, and security. Given a set of QoS attributes from a variety of sources, it is a challenge to sort through all of them and be able to get the best services that meet QoS requirement. In this paper, we describe a novel method by which Web services can be ranked and selected automatically based on a number of observed QoS parameters and feedback responses learned from prior knowledge. This new approach treats the observed Web services QoS attributes and target Web services relationship, represented by a matrix, as a statistical problem. Using singular value decomposition (SVD) technique, and an user assisted weighting system, implicit higher order correlations among Web services and their associated QoS attributes are extracted and used to estimate the selection of recommended Web services.