Service Level Agreement (SLA) Chains Supported by Cloud in a Complex Port Ecosystem with Competing Stakeholder Goals: Editorial

The increasing use of Cloud computing makes the development of high-quality Cloud-based applications a vital research area. Cloud computing, which provides inexpensive computing resources on the pay-as-you-go basis, is promptly gaining momentum as a substitute for traditional information technology (IT)-based organizations. As more and more users migrate their applications to Cloud environments, service level agreements (SLAs) between clients and Cloud providers become a key element to consider. Due to the dynamic nature of the Cloud, endless supervision of quality of service (QoS) attributes is necessary to honor the SLAs. Thus, Cloud computing faces the challenge of QoS, especially in relation to how a service provider can ensure appropriate QoS for its Cloud services. QoS is an inherent element, part of service-oriented architecture (SOA), to direct nonfunctional quality attributes of a service, such as the response time, price, or the supported security rules. Consequently, there is a requirement to grow architectures in order to respond correctly to the QoS requirements. The architecture should be able to change dynamically the amount of resources made available to the applications it hosts. Optimal resource utilization should be attained by providing (and maintaining at run time) each hosted application with the number of resources which is adequate to guarantee that the application SLA will not be violated. This chapter reflects the essential perceptions behind the QoS provision in the Cloud, identifies current and innovative quality attributes based on customers’ desires associated with SLA and identifies metrics to measure the deviation of QoS from predictables, with possible resolution in the outline of architecture for spontaneous supervision of QoS without violation of SLA. The existing intent of Cloud SLAs is inspected with a focus on QoS and customer requirements. Further, foremost research problems and scientific challenges in Cloud SLAs have been considered with possible reasons. Autonomic management architecture for dynamic provisioning of resources based on users QoS requirements to maximize efficiency and automatic fulfillment of SLA has also been proposed.

Because of the large number of different types of service level agreements (SLAs), computing resource markets face the challenge of low market liquidity. The authors therefore suggest restricting the number of different resource types to a small set of standardized computing resources to counteract this problem. Standardized computing resources are defined through SLA templates. SLA templates specify the structure of an SLA, the service attributes, the names of the service attributes, and the service attribute values. However, since existing approaches working with SLA templates are static so far, these approaches cannot reflect changes in user needs. To address this shortcoming, the chapter presents a novel approach to adaptive SLA matching. This approach adapts SLA templates based on SLA mappings of users. It allows Cloud users to define mappings between a public SLA template, which is available in the Cloud market, and their private SLA templates, which are used for various in-house business processes. Besides showing how public SLA templates are adapted to the demand of Cloud users, the chapter also analyzes the costs and benefits of this approach. Costs are incurred every time a user has to define a new SLA mapping to a public SLA template that has been adapted. In particular, it investigates how the costs differ with respect to the public SLA template adaptation method. The simulation results show that the use of heuristics for adaptation methods allows balancing the costs and benefits of the SLA mapping approach.

Cloud service providers mostly offer service level agreements (SLAs) in descriptive format which is not directly consumable by a machine or a system. Manual management of SLAs with growing usage of cloud services can be a challenging, erroneous and tedious task especially for the cloud service users (CSUs) acquiring multiple cloud services. The necessity of automating the complete SLA life cycle (which includes SLA description in machine readable format, negotiation, monitoring and management) becomes imminent due to complex requirements for the precise measurement of quality of service (QoS) parameters. In this work, the complete SLA life cycle management is presented using an extended SLA specification to support multiple CSU locations. A time efficient SLA negotiation technique is integrated with the extended SLA specification for concurrently negotiating with multiple cloud service providers (CSPs). After a successful negotiation process, the next major task in the SLA life cycle is to monitor the cloud services for ensuring the quality of service according to the agreed SLA. A distributed monitoring approach for the cloud SLAs is elaborated, in this work, which is suitable for services being used at single or multiple locations. The discussed monitoring approach reduces the number of communications of SLA violations to a monitoring coordinator by eliminating the unnecessary communications. The presented work on the complete SLA life cycle automation is evaluated and validated with the help of experiments and simulations.

A Service Level Agreement (SLA) represents an agreement between a cloud provider and cloud customer in the context of a particular service provision. This raises the following question: How to describe the SLA terms between prospective signatories, such as service levels, Quality of Service properties, penalties in case of SLA violation, etc. SLA can be represented by specialized languages for easing SLA preparation, automating SLA negotiation, adapting services automatically according to SLA terms, and reasoning about their composition. Therefore, the aim of this work is to present a comprehensive review of how SLAs are created, managed and used in web services and cloud computing environment. This paper provides a review of SLA languages specification. Among them the WSLA, WS-Agreement, SLA*, CSLA and SLAC. Then, a comparison of these languages in terms of the requirements is presented, highlighting their strengths and weaknesses.

Dynamically managing service level agreements (SLAs) is a non-trivial issue for both active media technology users and providers. Cloud computing is considered as one of the significant components of the rapidly emerging active media in the current era. As the technology grows rapidly, cloud computing requirements and techniques also change over time, while the current cloud SLA management methods are rigorous in terms of SLA contents updates with the technology innovation and user requirement change. In other words, public SLAs are used as templates, and when issuing a new SLA, it is necessary to map its requirements to all public SLAs. In addition, updating any consumer's SLA requires a cumbersome process of remapping their changed requirements to all public SLAs. This paper proposes a cloud computing SLA management mechanism based on the real options analysis concept to manage cloud SLAs in a dynamic manner. At the beginning, or when issuing a new SLA, the proposed framework receives a new user's requirements and maps these to all public SLAs, while executes only the most appropriate SLA based on options analysis and records/marks the other related solutions (SLAs) for future analysis to address any further change due to internal/external factor. This also provides a mechanism to effectively counter uncertainty parameters triggering dynamic change in cloud SLA management. The framework was deployed using Web SLA and Java followed by an experimental study to evaluate the efficacy and scalability of the proposed framework. The results show that the proposed framework provides efficient and scalable cloud SLA management mechanism.

A Service Level Agreement (SLA) represents an agreement between a service user and a provider in the context of a particular service provision. SLAs contain Quality of Service properties that must be maintained by a provider, and as agreed between a provider and a user/client. These are generally defined as a set of Service Level Objectives (SLOs). These properties need to be measurable and must be monitored during the provision of the service that has been agreed in the SLA. The SLA must also contain a set of penalty clauses specifying what happens when service providers fail to deliver the pre-agreed quality. Hence, an SLA may be used by both a user and a provider – from a user perspective, an SLA defines what is required – often defined using non-functional attributes of service provision. From a providers perspective, an SLA may be used to support capacity planning – especially if a provider is making it’s capability available to multiple users. An SLA may be used by a client and provider to manage their behaviour over time – for instance, to optimise their long running revenue (cost) or QoS attributes (such as execution time), for instance. The lifecycle of an SLA is outlined, along with various uses of SLAs to support infrastructure management. A discussion about WS-Agreement – the emerging standard for specifying SLAs – is also provided.

Service Level Agreements (SLAs) represent service management contracts that are processed by monitoring and measurement mechanisms for the evaluation of the signatories adherence to the agreed service levels during service execution. The paper discusses SLA data management characteristics that need to be considered in the design of data models for SLA documents. The SLA anatomy is introduced with respect to the Web Service Level Agreement (WSLA) [1] language specification. Furthermore, the paper highlights current obstacles for the integration of automated SLA management in the cloud business setting. The contributed SLA data analysis maps SLA terms to data management attributes according to their operational relevance during the SLA activity. We present an SLA digraph model for the automated SLA formulation and data handling. The SLA digraph is introduced as a programming module that sits on the application layer and communicates with backend data stores for the SLA persistence.

In the Internet of Things (IoT), billions of physical devices, distributed over a large geographic area, provide a near real-time state of the world. These devices’ capabilities can be abstracted as IoT services and delivered to users in a demand-driven way. In such a dynamic large-scale environment, a service provider who supports a service level agreement (SLA) can have a comprehensive competitive edge in terms of service quality management, service customization, optimized resource allocation, and trustworthiness. However, there is no consistent way of drafting an SLA with respect to describing heterogeneous IoT services, which obstructs automatic service selection, SLA negotiation, and SLA monitoring. In this paper, we propose an ontology, WIoT-SLA, to achieve semantic interoperability. We combine IoT service properties with two prominent web service SLA specifications: WS-Agreement and WSLA, to take advantage of their complementary features. This ontology is used to formalize the SLAs and SLA negotiation offers, which further facilitates the service selection and automatic SLA negotiation. It can also be used by a monitoring engine to detect SLA violations by providing the semantics of service level objectives (SLOs) and quality metrics. To evaluate our work, a prototype is implemented to demonstrate its feasibility and efficiency.

As various consumers tend to use personalized Cloud services, Service Level Agreements (SLAs) emerge as a key aspect in Cloud and Utility computing. The objectives of this doctoral research are 1) to support a flexible establishment of SLAs that enhances the utility of SLAs for both providers and consumers, and 2) to manage Cloud resources to prevent SLA violations. Because consumers and providers may be independent bodies, some mechanisms are necessary to resolve different preferences when they establish a SLA. Thus, we designed a Cloud SLA negotiation mechanism for interactive and flexible SLA establishment. The novelty of this SLA negotiation mechanism is that it can support advanced multi-issue negotiation that includes time slot and price negotiations. In addition, to prevent SLA violations, we provided a SLA-driven resource allocation scheme that selects a proper data center among globally distributed centers operated by a provider. Empirical results showed that the proposed SLA negotiation mechanism supports faster agreements and achieves higher utilities. Also, the proposed SLA-driven resource allocation scheme performs better in terms of SLA violations and the provider's profits.

A Service Level Agreement (SLA) is an electronic contract between the consumer and the provider of a service. It governs their business relationship by clarifying expectations and obligations of participating entities, with regard to the service and its quality. SLAs are already the prime paradigm for the description of cloud computing services. Once an SLA is established, the provider has to ensure that service quality remains within certain acceptable levels; and comply with the customer's demands until the end of the service life time. However, managing the SLAs is still a technical challenge that requires signi cant e ort to achieve autonomy, economy and e ciency. Current state-of-the-art in SLA management faces challenges such as SLA representation for cloud services; business-related SLA optimizations; service outsourcing and resource management. These areas constitute, as one would expect, major contemporary research topics. Hence, a structured methodology engineered for the management of the di erent phases of SLAs during its lifespan is of paramount importance, which indeed facilitates the realization of the cloud SLA management. To this aim, I present diversi ed models and approaches in SLA lifecycle management that address the aforementioned challenges and enable automatic service modeling, negotiation, provisioning and monitoring. During the SLA creation phase, I outline how to improve and simplify the structures that model SLAs. Furthermore, another objective of my approach is to minimize implementation and outsourcing costs for reasons of competitiveness, while respecting business policies for pro t and risk. During the SLA monitoring phase, I develop the strategies for virtual cloud resources selection and allocation during live migrations. Then, I apply an appropriate theoretical model for ne-grained yet simpli ed and practical monitoring of massive sets of SLAs, that separates the agreement's fault-tolerance concerns into multiple autonomous layers. The work at hand contributes a blueprint for the GWDG and its scienti c communities. The research that lead to this thesis was conducted as part of the SLA@SOI EU/FP7 Integrated Project (contract No. 216556).

Multithreading is widely used to increase processor throughput. As the number of shared resources increase, managing them while guaranteeing predicted performance becomes a major problem. Attempts have been made in previous work to ease this via different fairness mechanisms. In this article, we present a new approach to control the resource allocation and sharing via a service level agreement (SLA)-based mechanism; that is, via an agreement in which multithreaded processors guarantee a minimal level of service to the running threads. We introduce a new metric, C SLA , for conformance to SLA in multithreaded processors and show that controlling resources using with SLA allows for higher gains than are achievable by previously suggested fairness techniques. It also permits improving one metric (e.g., power) while maintaining SLA in another (e.g., performance). We compare SLA enforcement to schemes based on other fairness metrics, which are mostly targeted at equalizing execution parameters. We show that using SLA rather than fairness based algorithms provides a range of acceptable execution points from which we can select the point that best fits our optimization target, such as maximizing the weighted speedup (sum of the speedups of the individual threads) or reducing power. We demonstrate the effectiveness of the new SLA approach using switch-on-event (coarse-grained) multithreading. Our weighted speedup improvement scheme successfully enforces SLA while improving the weighted speedup by an average of 10% for unbalanced threads. This result is significant when compared with performance losses that may be incurred by fairness enforcement methods. When optimizing for power reduction in unbalanced threads SLA enforcement reduces the power by an average of 15%. SLA may be complemented by other power reduction methods to achieve further power savings and maintain the same service level for the threads. We also demonstrate differentiated SLA, where weighted speedup is maximized while each thread may have a different throughput constraint.

Various control algorithms are used in autonomic control to maintain Quality of Service (QoS) and Service Level Agreements (SLAs). Controllers are all based to some extent on models of the relationship between resources, QoS measures, and the workload imposed by the environment. This work discusses the range of algorithms with an emphasis on richer and more powerful models to describe non-linear performance relationships, and strong interactions among the system resources. A hierarchical framework is described which accommodates different scopes and timescales of control actions, and different control algorithms. The control algorithms and architectures can be considered in three stages: tuning, load balancing and provisioning. Different situations warrant different solutions, so this work shows how different control algorithms and architectures at the three stages can be combined to fit into different autonomic environments to meet QoS and SLAs across a large variety of workloads.

With concerns about the quality of telecom services rising, greater importance is being placed on the Service Level Agreement (SLA). Although telecom service providers are expanding the provision of SLA to satisfy enterprise customers' demands for service quality, they still tend to design SLA details from their standpoint. If the provision of SLA aims to improve telecom services for enterprise customers, and thus, enhance their loyalty, this approach and attempt should be revamped. At this juncture, it is considered a good attempt in the process of SLA provision to survey enterprise customers regarding the provision of SLA with the aim of overcoming the problems and to identify their demand and direction for improvement. Thus, this research seeks to review the major components of SLA including service level objectives (SLO), measurement and penalty, as well as additional factors following the projected structuring of the next-generation network. This review is expected to maximize achievements in the utilization of SLA provision as the most useful tool aimed at guaranteeing service quality.

We describe a novel framework for specifying and monitoring Service Level Agreements (SLA) for Web Services. SLA monitoring and enforcement become increasingly important in a Web Service environment where enterprise applications and services rely on services that may be subscribed dynamically and on-demand. For economic and practical reasons, we want an automated provisioning process for both the service itself as well as the SLA managment system that measures and monitors the QoS parameters, checks the agreed-upon service levels, and reports violations to the authorized parties involved in the SLA management process. Our approach to these issues is presented in this paper. The Web Service Level Agreement (WSLA) framework is targeted at defining and monitoring SLAs for Web Services. Although WSLA has been designed for a Web Services environment, it is applicable as well to any inter-domain management scenario, such as business process and service management, or the management of networks, systems and applications in general. The WSLA framework consists of a flexible and extensible language based on XML Schema and a runtime architecture comprising several SLA monitoring services, which may be outsourced to third parties to ensure a maximum of objectivity. WSLA enables service customers and providers to unambiguously define a wide variety of SLAs, specify the SLA parameters and the way they are measured, and relate them to managed resource instrumentations. Upon receipt of an SLA specification, the WSLA monitoring services are automatically configured to enforce the SLA. An implementation of the WSLA framework, termed SLA Compliance Monitor, is publicly available as part of the IBM Web Services Toolkit.

The service level agreement (SLA) is a mutual contract between the service provider and consumer which determines the agreed service level objective (SLO). The common SLA is a plain documental agreement without any relation to other dependent SLAs during the different layers of cloud computing. Hence, the cloud computing environment needs the hierarchical and autonomic SLA. This paper proposes the SH-SLA model to generate a hierarchical self-healing SLA in cloud computing. The self-healing ability contains the SLA monitoring, violation detecting and violation reacting processes. In SH-SLA, the related SLAs communicate with each other hierarchically. The SLA would be able to check its QoS and notify the recent status to dependent SLAs. Furthermore, SH-SLA could prevent or propagate the notified violations by an urgent reaction. Consequently, the service providers have a great chance to prevent the violated SLA before sensing by end users. The SH-SLA model is simulated and the experiment results have presented the violation detection and reaction abilities of the proposed model in cloud computing. Besides, the end users meet the lesser violations in SH-SLA than the common SLA.