Service Level Agreements Management Research Articles

Towards real-time anomalies monitoring for QoE indicators

Anomaly detection and characterization is a main topic for network managers. Although quality-of-service (QoS) indicators can help to infer problem occurrence, they do not provide immediate insight on the user’s perceived quality. Evolved service-level agreements (SLA) will likely be established in terms of quality of experience (QoE) indicators. QoS metrics composing the QoE indicators need to be monitored on a real-time basis by the SLA management tools in order to detect anomalies driving to contract violations. Monitoring SLA contracts may involve the surveillance of individual application sessions for several users. In this work, we address the problem of anomaly detection with impact on a relatively large number of users, either on one or on several types of applications simultaneously. We propose a method to characterize the state of the network, representing QoE indicators as time series and reducing the dimension of the data set. The singular spectrum analysis (SSA) method, using a combination of geometric and statistical methods, is proposed as an analysis tool in order to detect anomalies on QoE indicator evolution.

Lifetime service level agreement management with autonomous agents for services provision

In the web services environment, service level agreements (SLA) refers to mutually agreed understandings and expectations between service consumers and providers on the service provision. Although management of SLA is critical to wide adoption of web services technologies in the real world, support for it is very limited nowadays, especially in web service composition scenarios. There lacks adequate frameworks and technologies supporting various SLA operations such as SLA formation, enforcement, and recovery. This paper presents a novel agent-based framework which utilises the agents’ ability of negotiation, interaction, and cooperation to facilitate autonomous SLA management in the context of service composition provision. Based on this framework, mechanisms for autonomous SLA operations are proposed and discussed. Results from simulations show that by integrating agents and web services the framework can address issues of SLA management drawn from sophisticated service composition scenarios.

Privacy management service contacts as business opportunity

The article discusses the service level agreement (SLA) and the privacy aspect. Economic and business considerations around privacy, and privacy of information in general have different levels of analysis and enforcement, as mentioned in the article. Economic and business considerations, require economic and business value to be defined and transacted upon. It should also be stressed that legal aspects are essential, as they may determine the nature of some privacy features as well as limits. Legal aspects obviously also apply to the fulfillment of the transactions between the economic individual and economic agents, directly or indirectly. The paper defines the framework and implementation of SLA management for privacy, as well as privacy metrics. A case study implementation in Cisco was mentioned. This article recognizes that privacy SLA's business value does not extend to all domains. But there are application domains where their introduction would be a major incentive scheme to increase controlled information and business interactions.

Dynamic SLAs management in service oriented environments

The increasing adoption of service oriented architectures across different administrative domains, forces service providers to use effective mechanisms and strategies of resource management in order for them to be able to guarantee the quality levels their customers demands during service provisioning. Service level agreements (SLA) are the most common mechanism used to establish agreements on the quality of a service (QoS) between a service provider and a service consumer. The WS-Agreement specification, developed by the Open Grid Forum, is a Web Service protocol to establish agreements on the QoS level to be guaranteed in the provision of a service. The committed agreement cannot be modified during service provision and is effective until all activities pertaining to it are finished or until one of the signing party decides to terminate it. In B2B scenarios where several service providers are involved in the composition of a service, and each of them plays both the parts of provider and customer, several one-to-one SLAs need to be signed. In such a rigid context the global QoS of the final service can be strongly affected by any violation on each single SLA. In order to prevent such violations, SLAs need to adapt to any possible needs that might come up during service provision. In this work we focus on the WS-Agreement specification and propose to enhance the flexibility of its approach. We integrate new functionality to the protocol that enable the parties of a WS-Agreement to re-negotiate and modify its terms during the service provision, and show how a typical scenario of service composition can benefit from our proposal.

Probabilistic QoS and Soft Contracts for Transaction-Based Web Services Orchestrations

Service level agreements (SLAs), or contracts, have an important role in web services. They define the obligations and rights between the provider of a web service and its client, about the function and the Quality of the service (QoS). For composite services like orchestrations, contracts are deduced by a process called QoS contract composition, based on contracts established between the orchestration and the called web services. Contracts are typically stated as hard guarantees (e.g., response time always less than 5 msec). Using hard bounds is not realistic, however, and more statistical approaches are needed. In this paper we propose using soft probabilistic contracts instead, which consist of a probability distribution for the considered QoS parameter—in this paper, we focus on timing. We show how to compose such contracts, to yield a global probabilistic contract for the orchestration. Our approach is implemented by the TOrQuE tool. Experiments on TOrQuE show that overly pessimistic contracts can be avoided and significant room for safe overbooking exists. An essential component of SLA management is then the continuous monitoring of the performance of called web services, to check for violations of the SLA. We propose a statistical technique for run-time monitoring of soft contracts.

Knowledge representation concepts for automated SLA management

Outsourcing of complex IT infrastructure to IT service providers has increased substantially during the past years. IT service providers must be able to fulfil their service-quality commitments based upon predefined Service Level Agreements (SLAs) with the service customer. They need to manage, execute and maintain thousands of SLAs for different customers and different types of services, which needs new levels of flexibility and automation not available with the current technology. The complexity of contractual logic in SLAs requires new forms of knowledge representation to automatically draw inferences and execute contractual agreemen ts. A logic-based approach provides several advantages including automated rule chaining allowing for compact knowledge representation as well as flexibility to adapt to rapidly changing business requirements. We suggest logical formalisms for the representation and enforcement of SLA rules and describe a proof-of-concept implementation. The article describes selected formalisms of the ContractLog KR and their adequacy for automated SLA management and presents results of experiments and examples from common industry use cases to demonstrate the expressiveness of the language and the scalability of the approach.

QoS in Node-Disjoint Routing for Ad Hoc Networks

Ad hoc network (MANET) is a collection of mobile nodes that can communicate with each other without using any fixed infrastructure. To support multimedia applications such as video and voice MANETs require an efficient routing protocol and quality of service (QoS) mechanism. Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol in MANETs: it reduces routing overhead dramatically and achieves multiple node-disjoint routing paths. QoS support in MANETs is an important issue as best-effort routing is not efficient for supporting multimedia applications. This paper presents a novel adaptation of NDMR, QoS enabled NDMR, which introduces agent-based SLA management. This enhancement allows for the intelligent selection of node-disjoint routes based on network conditions, thus fulfilling the QoS requirements of Service Level Agreements (SLAs).

PCT Commissioning: how community nurse involvement can be encouraged

Commissioning is the process by which PCTs identify the health needs of their population and make prioritized decisions to secure care to meet those needs within available resources. It includes longer term strategic planning, medium term planning (three year Local delivery Plans) and the shorter term agreement and performance management of service level agreements. The process should involve the public, engage clinicians, and be conducted on a whole system basis, informed by health equity audits, and carried through with the full participation of other stakeholders including NHS Trusts, local authority(s) and the voluntary sector (NHS Modernization Agency, 2004).

Online end‐to‐end quality of service monitoring for service level agreement management

AbstractA major challenge in network and service level agreement (SLA) management is to provide Quality of Service (QoS) demanded by heterogeneous network applications. Online QoS monitoring plays an important role in the process by providing objective measurements that can be used for improving network design, troubleshooting and management. Online QoS monitoring becomes increasingly difficult and complex due to the rapid expansion of the Internet and the dramatic increase in the speed of network. Sampling techniques have been explored as a means to reduce the difficulty and complexity of measurement. In this paper, we investigate several major sampling techniques, i.e. systematic sampling, simple random sampling and stratified sampling. Performance analysis is conducted on these techniques. It is shown that stratified sampling with optimum allocation has the best performance. However, stratified sampling with optimum allocation requires additional statistics usually not available for real‐time applications. An adaptive stratified sampling algorithm is proposed to solve the problem. Both theoretical analysis and simulation show that the proposed adaptive stratified sampling algorithm outperforms other sampling techniques and achieves a performance comparable to stratified sampling with optimum allocation. A QoS monitoring software using the aforementioned sampling techniques is designed and tested in various real networks. Copyright © 2007 John Wiley & Sons, Ltd.

Autonomous service level agreement negotiation for service composition provision

Efficient management of service level agreements which specify mutually-agreed understandings and expectations of service provision has been a subject of research for a few years. A critical issue in this area is for service consumers and service providers to effectively achieve agreements on non-functional aspects of service provision, such as quality of service. However, this issue has not been well addressed, especially in the context of service composition provision which implies the establishment of a set of interrelated agreements on quality of service between the service consumer and multiple service providers offering various services in the composition. There is a lack of supporting frameworks and techniques to automatically and dynamically achieve agreements on quality of service constraints for individual services in a service composition, aiming at fulfilling composition’s end-to-end quality of service requirements. This paper reports the authors’ recent research in addressing this issue, using the agent technology. In this research, the service level agreements for a service composition are established through autonomous agent negotiation. To enable this, an innovative framework is proposed in which the service consumer is represented by a set of agents who negotiate quality of service constraints with the service providers for various services in the composition. This negotiation is well coordinated in order to achieve end-to-end quality of service requirements. Based on this framework, a new negotiation protocol is presented to support coordinated negotiation. A utility-function-based decision-making model is proposed based on which agents can proactively decide on the course of further actions. Moreover, this paper also contributes the novel design of the negotiation Web service on the service providers’ side for the purpose of interoperability. Finally, the prototype implementation for the purpose of proof-of-concept is discussed.

The Design, Usage, and Performance of GRUBER: A Grid Usage Service Level Agreement based BrokERing Infrastructure

We present GRUBER, a Grid Resource Usage service level agreement (uSLA) based BrokERing infrastructure, aimed at addressing the challenging issues that can arise within virtual organizations (VOs) that integrate participants and resources spanning multiple physical administrative domains. In such environments, participants delegate to one or more VOs the right to use certain resources subject to local policy and service level agreements; each VO then uses those resources subject to VO policy. GRUBER supports the explicit representation, enforcement, and management of service level agreements (SLAs) concerning resource usage (uSLAs) that can serve as an objective organizing principle for controlled resource sharing in distributed systems. uSLAs express how resources must be used over various time intervals and represent a novelty for the Grid domain. This paper provides a detailed overview of the GRUBER infrastructure, the evolution of its design to improve scalability, specifically the distribution of the resource brokering service, and the extended support for dynamic environments. We also present various results achieved over time that demonstrate both the utility and performance of GRUBER under various application workloads and scenarios.

Internet end-to-end delay dynamics

End-to-end delay is one of the most important characteristics of Internet end-to-end packet dynamics, which can be applied to quality of services (QoS) management, service level agreement (SLA) management, congestion control algorithm development, etc. Nonstationarity and nonlinearity are found by the analysis of various delay series measured from different links. The fact that different types of links have different degree of Self-Similarity is also obtained. By constructing appropriate network architecture and neural functions, functional networks can be used to model the Internet end-to-end nonlinear delay time series. Furthermore, by using adaptive parameter studying algorithm, the nonstationarity can also be well modeled. The numerical results show that the provided functional network architecture and adaptive algorithm can precisely characterize the Internet end-to-end delay dynamics.

Dynamic inter-SLA resource sharing in path-oriented differentiated services networks

This paper proposes novel resource sharing schemes for differentiated services (DiffServ) networks, to achieve both high resource utilization and quality of service (QoS) guarantee. Service level agreements (SLAs) are negotiated at network boundaries and supported by path-oriented resource mapping within the network. The recently proposed SLA management scheme based on virtual partitioning (Bouillet et al., 2002) allows overloaded SLAs to exploit the spare capacity of underloaded SLAs for efficient resource utilization, however, at the the cost of possible SLA violation of the underloaders. In the bandwidth borrowing scheme proposed here, the dedicated bandwidth for underloaded SLAs is determined and adaptively adjusted at network boundaries according to the actual traffic load and QoS policies; the available spare capacity is then properly distributed to related links for lending to others. On the other hand, the traffic flows admitted with borrowed bandwidth are tagged and may be preempted later when the original bandwidth owner needs to claim back the resources. Through a detailed implementation design and extensive computer simulation results we show that, by bandwidth borrowing, both SLA compliance and high resource utilization can be achieved in various load conditions, with some side benefits such as call-level service differentiation, small admission overhead, and convenience for policy-based management. In addition, we propose a distributed bandwidth pushing scheme that can dynamically adjust the spare bandwidth distribution over the network. Combining bandwidth pushing with bandwidth borrowing, the resource utilization can be further improved.

Utilizing unreliable public resources for higher profit and better SLA compliance in computing utilities

Computing utilities are emerging as an important part of the infrastructure for outsourcing computer services. Fundamental to outsourcing is the notion of quality of service, which is defined by service level agreements (SLAs) between the computing utilities and clients. One of the major objectives of computing utilities is to maximize their net profit while maintaining customer loyalty. To achieve this objective, the computing utilities should meet or exceed their SLA constraints most of the time. Defining the SLAs conservatively might be one way of easily achieving these goals. However, by tuning the SLA parameters conservatively the computing utility might under utilize its resources with a resultant loss of revenue. Therefore, we can see two main issues with SLA management: designing SLAs competitively so that expected revenue for the computing utility is maximized and maintaining the operating conditions such that SLAs are satisfied with very high probability. In this paper, we show that inducting unreliable public resources into a computing utility enables more competitive SLAs while maintaining higher levels of run time compliances as well as maximizing profit. Our scheduling algorithms assume that idle cycles from public resources are available in plenty, therefore, the performance gains do not incur any additional financial cost. However, there is communication overhead when public resources from a wide area network is included. This overhead is kept to the minimum by enabling the scheduler work without any monitoring on the public resources.

Session-Level and Network-Level SLA Structures and VoIP Service Policy over DiffServ-Based MPLS Networks

SUMMARY This paper proposes a framework for session-level SLA (Service Level Agreement) and network-level SLA management to provide QoS-oriented application services over DiffServ/MPLS networks. DiffServ and MPLS technologies enhance the capability of QoS guarantee on IP network, and application service provider can provide QoS-oriented application services to their customers based on the transport networks. The example of using our approaches in the VoIP service involving the network service provider, the VoIP service provider, and the VoIP customers are examined. The session-level SLA between VoIP service provider and VoIP customer and the network-level SLA (N-SLA) between network provider and VoIP service provider are constructed in this paper. Besides, the VoIP service provider faces the QoS-mapping issue and the balance between revenue and cost, i.e., how to contract the N-SLA. Therefore, we introduce an off-line SLA evaluation scheme, a heuristic optimization algorithm and an on-line SLA process method to provide VoIP service policy, and then the optimal QoS-mapping can be resolved. The concept of this framework of session-level SLA and network-level SLA management can be extended easily into other real-time multimedia and non-real time data services.

Towards an Architecture for the Mobile Grid (Architektur für ein Mobiles Grid)

Summary Mobility is becoming a central aspect of everyday life and must not be ignored by the ongoing efforts in defining the Next Generation Grid architectures. Currently existing network agnostic Grid middleware solutions are duplicating functionality available from lower layers and cannot benefit from a richer set of additional information available such as the user or device context. In this article we will motivate why an integration of the infrastructure services built for supporting mobile users can be beneficial for the realization of a Next Generation Grid. Starting from a definition of the term Mobile Grid it is shown how new kind of adaptive applications can be realized and how the major obstacles for the wide take up of Grid solutions can be addressed. In particular how grid solutions can benefit from user authentication models, cross-organizational accounting, auditing and billing are covered. Beside the opportunities of this integration several new challenges in particular related to workflows and the management of Service Level Agreements will be outlined. This so called Cross-Layer Cooperation is seen as one of the major differences to other Next Generation Grids based on the Open Grid Service Architecture (OGSA) [10] approach. In the next section considerations related to deployment of Mobile Grids and why the approach outlined in the OGSA architecture to model grids as the composition of individual services is not adequate for this are presented.

PROQOS?Dynamic SLA Management in DiffServ Space Links

Several base elements for the provision of quality of service guarantees have been developed in the recent past. Of these, the Differentiated Services (DiffServ) architecture stands out as the most promising. In spite of this, various issues remain, especially when multidomain DiffServ services are concerned. In this case, some forms of distributed management of Service Level Agreements that allow the specification, exchange, enforcement and monitoring of quality of service data must be in place. Although, again, some isolated solutions exist for each of these problems, considerable effort is necessary to make them work together. The project presented in this paper tried to assess the feasibility of providing differentiated quality of service in satellite IP networks, by developing a dynamic Service Level Agreement management solution for an IP over Digital Video Broadcast Satellite system. The functionality of the implemented system comprises system configuration, dynamic SLA negotiation, QoS monitoring and metering, SLA conformance checking, and QoS reporting to customers.

Managing service level agreements in Premium IP networks: a business-oriented approach

This paper presents a market-enabling framework where users, content providers and network operators can interact in the seamless, transparent sale and delivery of a wide range of services. The framework allows for dynamic creation, configuration and delivery of services with quality assurance, via automated management of Service Level Agreements (SLAs). We propose an approach relying on a systemic treatment of business, service and network layer issues, which translates into a layered architecture where components belonging to different levels interact on the basis of a mediation paradigm. We use mediation as a generic term for a combination of negotiation, brokerage and state notification, jointly concurring to the realization of the entire life-cycle of a service.

Self‐aware management of IP networks with QoS guarantees

AbstractSelf‐aware management allows the network to react and to adapt to changes of situation. In this paper an architecture is described for self‐aware management of IP networks offering QoS guarantees. This architecture uses policy‐based management and multi‐agent systems. The originality of the present approach lies in the intention to give a real autonomy to the components intervening in the chain of services in terms of internal decisions and configuration. Our solution allows the self‐configuration, self‐provisioning and self‐monitoring of service as well as the proactive service level agreement management. Copyright © 2004 John Wiley & Sons, Ltd.

Preface

Utility computing is a recent development in IT (information technology) outsourcing, whereby service capacity is provided as needed and the customer pays only for actual use. To provide what amounts to computing on demand, providers face business and technological challenges, including pricing of new services, adopting new business models, automated management of resource provisioning, and management of service level agreements (SLAs).