Showing papers on "Service level published in 2009"

Cost of Virtual Machine Live Migration in Clouds: A Performance Evaluation

Abstract: Virtualization has become commonplace in modern data centers, often referred as "computing clouds". The capability of virtual machine live migration brings benefits such as improved performance, manageability and fault tolerance, while allowing workload movement with a short service downtime. However, service levels of applications are likely to be negatively affected during a live migration. For this reason, a better understanding of its effects on system performance is desirable. In this paper, we evaluate the effects of live migration of virtual machines on the performance of applications running inside Xen VMs. Results show that, in most cases, migration overhead is acceptable but cannot be disregarded, especially in systems where availability and responsiveness are governed by strict Service Level Agreements. Despite that, there is a high potential for live migration applicability in data centers serving modern Internet applications. Our results are based on a workload covering the domain of multi-tier Web 2.0 applications.

Service Level Agreement in Cloud Computing

Abstract: Cloud computing that provides cheap and pay-as-you-go computing resources is rapidly gaining momentum as an alternative to traditional IT Infrastructure. As more and more consumers delegate their tasks to cloud providers, Service Level Agreements(SLA) between consumers and providers emerge as a key aspect. Due to the dynamic nature of the cloud, continuous monitoring on Quality of Service (QoS) attributes is necessary to enforce SLAs. Also numerous other factors such as trust (on the cloud provider) come into consideration, particularly for enterprise customers that may outsource its critical data. This complex nature of the cloud landscape warrants a sophisticated means of managing SLAs. This paper proposes a mechanism for managing SLAs in a cloud computing environment using the Web Service Level Agreement(WSLA) framework, developed for SLA monitoring and SLA enforcement in a Service Oriented Architecture (SOA). We use the third party support feature of WSLA to delegate monitoring and enforcement tasks to other entities in order to solve the trust issues. We also present a real world use case to validate our proposal.

The relationship between strategic orientation, service innovation, and performance

Abstract: Purpose – The purpose of this paper is to determine how a firm's strategic orientation affects service innovation capability and the resulting impact on market performance.Design/methodology/approach – A survey was administered to supply chain executives. Structural equation modeling was used to analyze the relationships among the following constructs: customer orientation, competitor orientation, cost orientation, service innovation, and market performance.Findings – Although the relationship between cost orientation and service innovation is not supported, the relationships between customer orientation and competitor orientation and service innovation are supported. Additionally, the relationship between service innovation and market performance is supported.Research limitations/implications – This study is one of a limited number of studies which has empirically addressed service innovation. Additional research is needed to address the impact of a firm's strategic orientation on product innovation capa...

A survey and taxonomy of infrastructure as a service and web hosting cloud providers

Abstract: With an increasing number of providers claiming to offer Cloud infrastructures, there is a lack in the community for a common terminology, accompanied by a clear definition and classification of Cloud features. We conduct in this paper a survey on a selection of Cloud providers, and propose a taxonomy of eight important Cloud computing elements covering service type, resource deployment, hardware, runtime tuning, business model, middleware, and performance. We conclude that the provisioning of Service Level Agreements as utilities, of open and interoperable middleware solutions, as well as of sustained performance metrics for high-performance computing applications are three elements with the highest need of further community research.

Operation control for deploying and managing software service in a virtual environment

Abstract: A system and method can deploy and manage software services in virtualized and non-virtualized environments. The system provides an enterprise application virtualization solution that allows for centralized governance and control over software and Java applications. Operations teams can define policies, based on application-level service level agreements (SLA) that govern the allocation of hardware and software resources to ensure that quality of service (QoS) goals are met across virtual and non-virtualized platforms. The system use a rules engine that can compare administrator defined constraints with runtime metrics; generate events when a constraint is violated by a metric of the runtime metrics and generate events when a constraint is violated by a metric of the runtime metrics.

Healthcare supply chain management in Malaysia: a case study

Abstract: Purpose – The purpose of this paper is to evaluate inventory management in the private healthcare sector in Malaysia, with a particular focus on the distribution of medicines from a wholesaler to clinics. Currently, there are issues with service levels to clinics that need addressing. Design/methodology/approach – The paper adopts a case study approach, with data collected through process mapping, interviews and data analysis. Data flow diagrams are used to visualise the organization's supply chain current and future process. Interviews are used to identify the main supply chain issues, with triangulation of these opinions through data analysis. Findings – The findings identify two main issues within the case study company – urgent orders and stock availability at the wholesaler. From this, a future state design of the supply chain is proposed, based around vendor-managed inventory. Barriers to achieving this are also identified, including consideration of current supply chain management capabilities in Malaysia. Research limitations/implications – Only a single case study supply chain is studied, although two echelons are investigated. While this may limit the generalisation of the findings, there is value in demonstrating the benefits modern supply chain management techniques can bring to developing world healthcare supply chains. Practical implications – The paper shows that modern supply chain management techniques can bring benefits to healthcare supply chains in developing countries. Originality/value – The value of the paper arises from providing a detailed analysis of a healthcare supply chain in the developing world. There have been only a small number of other studies published in the literature.

The relationship between internal and external service quality

Abstract: Purpose – The purpose of this paper is to provide experimental evidence supporting the view that internal service quality has a direct effect on external service quality.Design/methodology/approach – The study focuses on the restaurant industry in Greece. Waiters are considered as internal customers and kitchen personnel as internal suppliers. Inferential analysis included factor analysis on individual waiter and customer data as well as canonical correlation analysis on a restaurant level.Findings – Factor analysis of external service quality revealed six factors including product, organizational image, safety and choice, empathy, reliability as well as responsiveness. Internal service quality factors, additional to those found in external service quality research, included professionalism and internet. Canonical correlation revealed that the internal service quality dimensions of safety, reliability and internet exert a direct positive influence on the external service quality dimensions of organization...

Capacitated remanufacturing with service level constraints

Abstract: This research examines production planning and control for a remanufacturer that can sell returned items on a graded as-is basis or remanufacture the returned items. Using a GI/G/1 queuing network, we model the firms decision to remanufacture an optimal product mix over the long run that maximizes profits while maintaining a desired service level. We further use simulation to explore dispatching heuristics that can be used at the shop-floor level to achieve the desired optimal product mix, while meeting the service level constraint. Our research is grounded in actual practice and the results provide key insights into the decision-making process required to maximize profits and minimize average flow times for remanufactured products.

ABC classification: service levels and inventory costs

Abstract: ABC inventory classifications are widely used in practice, with demand value and demand volume as the most common ranking criteria. The standard approach in ABC applications is to set the same service level for all stock keeping units (SKUs) in a class. In this paper, we show (for three large real life datasets) that the application of both demand value and demand volume as ABC ranking criteria, with fixed service levels per class, leads to solutions that are far from cost optimal. An alternative criterion proposed by Zhang et al. performs much better, but is still considerably outperformed by a new criterion proposed in this paper. The new criterion is also more general in that it can take criticality of SKUs into account. Managerial insights are obtained into what class should have the highest/lowest service level, a topic that has been disputed in the literature.

1000 islands: an integrated approach to resource management for virtualized data centers

Abstract: Recent advances in hardware and software virtualization offer unprecedented management capabilities for the mapping of virtual resources to physical resources. It is highly desirable to further create a "service hosting abstraction" that allows application owners to focus on service level objectives (SLOs) for their applications. This calls for a resource management solution that achieves the SLOs for many applications in response to changing data center conditions and hides the complexity from both application owners and data center operators. In this paper, we describe an automated capacity and workload management system that integrates multiple resource controllers at three different scopes and time scales. Simulation and experimental results confirm that such an integrated solution ensures efficient and effective use of data center resources while reducing service level violations for high priority applications.

Performance Evaluation of Cloud Computing Offerings

Abstract: Advanced computing on cloud computing infrastructures can only become viable alternative for the enterprise if these infrastructures can provide proper levels of nonfunctional properties (NPFs). A company that focuses on service-oriented architectures (SOA) needs to know what configuration would provide the proper levels for individual services if they are deployed in the cloud. In this paper we present an approach for performance evaluation of cloud computing configurations. While cloud computing providers assure certain service levels, this it typically done for the platform and not for a particular service instance. Our approach focuses on NFPs of individual services and thereby provides a more relevant and granular information. An experimental evaluation in Amazon Elastic Compute Cloud (EC2) verified our approach.

Comprehensive QoS monitoring of Web services and event-based SLA violation detection

Abstract: In service-oriented systems, Quality of Service represents an important issue which is often considered when selecting and composing services. For receiving up-to-date information, non-functional properties such as response time or availability can be continuously monitored using server- or clientside approaches. However, both approaches have strengths and weaknesses. In this paper, we present a framework that combines the advantages of client- and server-side QoS monitoring. It builds on event processing to inform interested subscribers of current QoS values and possible violations of Service Level Agreements. These events can trigger adaptive behavior such as hosting new service instances if the QoS is not as desired. We describe our QoS monitoring approach in detail, show how it was integrated into the VRESCo service runtime environment, and evaluate the accuracy of the presented monitoring techniques.

Case-based reinforcement learning for dynamic inventory control in a multi-agent supply-chain system

Abstract: Reinforcement learning (RL) appeals to many researchers in recent years because of its generality. It is an approach to machine intelligence that learns to achieve the given goal by trial-and-error iterations with its environment. This paper proposes a case-based reinforcement learning algorithm (CRL) for dynamic inventory control in a multi-agent supply-chain system. Traditional time-triggered and event-triggered ordering policies remain popular because they are easy to implement. But in the dynamic environment, the results of them may become inaccurate causing excessive inventory (cost) or shortage. Under the condition of nonstationary customer demand, the S value of (T, S) and (Q, S) inventory review method is learnt using the proposed algorithm for satisfying target service level, respectively. Multi-agent simulation of a simplified two-echelon supply chain, where proposed algorithm is implemented, is run for a few times. The results show the effectiveness of CRL in both review methods. We also consider a framework for general learning method based on proposed one, which may be helpful in all aspects of supply-chain management (SCM). Hence, it is suggested that well-designed ''connections'' are necessary to be built between CRL, multi-agent system (MAS) and SCM.

Inventory Models for Substitutable Products: Optimal Policies and Heuristics

Abstract: In this paper, we examine the nature of optimal inventory policies in a system where a retailer manages substitutable products. We first consider a system with two products 1 and 2 whose total demand is D and individual demands are negatively correlated. A fixed proportion of the unsatisfied customers for an item will purchase the other item, if it is available in inventory. For the single period case, we show that the optimal inventory levels of the two items can be computed easily and follow what we refer to as "partially decoupled" policies, i.e. base stock policies that are not state dependent, in certain critical regions of interest both when D is known and random. Furthermore, we show that such a partially decoupled base-stock policy is optimal even in a multi-period version of the problem for known D for a wide range of parameter values and in an N-product single-period model under some restrictive conditions. Using a numerical study, we show that heuristics based on the de-coupled inventory policy perform well in conditions more general than the ones assumed to obtain the analytical results. The analytical and numerical results suggest that the approach presented here is most valuable in retail settings for product categories where the level of substitution between items in a category is not high, demand variation at the aggregate level is not high and service levels or newsvendor ratios are high.

Business Impact of Relay Deployment for Coverage Extension in 3GPP LTE-Advanced

Abstract: Relays are expected to be a cost efficient way to fulfill requirements on high data rate coverage in next generation cellular networks, like LTE-Advanced. This paper presents a cost model and the respective analysis used for investigating the impact of relaying on cost savings for operators. The approach consists of defining the service level that next generation cellular networks should provide and deriving deployments of eNBs and RNs (or equivalently iso- performance scenarios) that fulfill these requirements. Iso- performance scenarios are therefore obtained by means of simulations and compared in the cost model.

Quality of resilience as a network reliability characterization tool

Abstract: With the increased role of resilience in modern networks, the existing quality of service is required to be expanded with service availability and maintainability. Recently, studies have shown the strong limitation of the common availability metrics for measuring the user's quality of experience. In this article a joint specification of QoS definitions with a sophisticated service resilience characterization is proposed, and a concept called quality of resilience is defined. In this unified performance metric, the frequency and length of service interruption are evaluated. It can be used as a tool for characterization of network reliability, as well as comparison and selection of recovery methods. Additionally, by including it in service level agreements, new and more complex requirements of commercial applications can be guaranteed.

Staffing multi-skill call centers via search methods and a performance approximation

Abstract: A multi-skill staffing problem in a call center where the agent skill sets are exogenous and the call routing policy has well-specified features of overflow between different agent types is addressed. Constraints are imposed on the service level for each call class, defined here as the steady-state fraction of calls served within a given time threshold, excluded. An approximation of these service levels is developed that allows an arbitrary overflow mechanism and customer abandonment. A two-stage heuristic that finds good solutions to mathematical programs with such constraints is developed. The first stage uses search methods supported by the approximation. Because service level approximation errors may be substantial, the solution is adjusted in a second stage in which performance is estimated by simulation. Realistic problems of varying size and routing policy are solved. The proposed approach is shown to be competitive with (and often better than) previously available methods. [Supplementary materials...

A Policy-Based Middleware for Web Services SLA Negotiation

Abstract: Negotiation of Service Level Agreements (SLAs) is very important for maintaining Quality of Service (QoS) of composite Web services-based business processes. The process of negotiation involves specification of negotiation parameters, exchanging offers to conduct the actual negotiation process, and then finally generating the formal SLA if the negotiating parties come to a consensus. We propose a Negotiation Broker (NB) middleware framework to facilitate automated negotiations of SLAs for Web services in a Service Oriented Architecture (SOA). High level business goals, contexts, preferences, constraints, and values of the negotiation issues are expressed as a policy specification by each of the negotiating parties. The NB maps the policy specifications to low level negotiation strategy models and parameters in order to conduct the negotiation locally as a trusted broker. We present a model and an example of the high level negotiation policy specification. We also present our NB framework including a prototype implementation to illustrate the mapping of the policy to a time-dependent negotiation strategy model.

Component commonality: models with product-specific service constraints*

Abstract: Common components are used extensively for reasons including product postponement and expediting new product development. We consider a two-stage assemble-to-order system with two products having uniformly distributed demand, one common component, and product-specific components. We develop optimization models in which the cost-minimizing inventory of the components must be determined and allocated to products in order to meet product-specific service level constraints. We compare two different commonality models based on whether or not the products are prioritized. A distinctive feature of our study is the use of product-specific service levels. We compare our results with models using aggregate service levels.

Consumer reaction to crowding for extended service encounters

Abstract: – Much of the research on crowding in a service context has focused on customer reaction to crowding in a retail setting. This paper seeks to examine the effect of consumer goals on consumers' reactions to crowding for extended service encounters., – The authors used a 2 (Crowding: crowded or not crowded) × 2 (Goal: utilitarian or hedonic) × 2 (Service level: bad or good) factorial, between‐subjects design to test hypotheses. Service level and tolerance for crowding were entered as control variables. A service encounter in a casual restaurant was used as the service setting in the study. Subjects were randomly assigned to a written scenario describing an experience in a restaurant. They were then shown a photograph depicting the interior of the restaurant., – Consumption goal moderates the effect of perceived crowding on satisfaction. Significantly lower satisfaction ratings are associated with a crowded service environment when the primary consumption goal for the service experience is utilitarian, rather than hedonic, in nature. Furthermore, regardless of the consumption goal, crowding negatively impacts positive in‐store behaviors (i.e. desire to spend more money and time at the restaurant)., – The study was limited to one extended service setting. Future research across other extended service settings is needed establish the generalizability of the findings., – The study has implications for the design of the service facility and the application of demand‐shifting revenue management strategies., – The paper extends the literature on shopping motivations to extended service settings by examining the effect of consumer goals on consumers' reactions to crowding, specifically consumer satisfaction with, and consumer behaviors within, the extended service encounter.