Service Level Agreement Specification Research Articles

SLA-Driven Software Orchestration in Industry 4.0

In the Industry 4.0 vision, the orchestration of software components plays a crucial role in enabling the continuous reconfiguration, programming, and evolution of the factory floor elements. The objective of an Industry 4.0 software orchestration system is to manage the software elements controlling one or more industrial processes with the purpose of enforcing specific Service Level Agreements (SLAs) for each connected use case (e.g., cooperative robots and connected workers). The orchestration systems currently available are not equipped to guarantee programmable industrial SLA, making it difficult to meet carrier grade reliability and reduced time to repair required by Operational Technology (OT). This article investigates research directions and use cases to manage programmable SLAs with four criticality levels in order to enable the use of orchestration in industrial scenarios. The main contribution is an approach, differentiated by workload criticality level, that uses proactive and reactive orchestration actions to meet industrial functional and non-functional requirements, and to mitigate SLA violations. The approach is exemplified through Industry 4.0 use-case scenarios.

Pareto-Optimised Fog Storage Services with Novel Service-Level Agreement Specification

(1) Background: Cloud storage is often required for successful operation of novel smart applications, relying on data produced by the Internet of Things (IoT) devices. Big Data processing tasks and management operations for such applications require high Quality of Service (QoS) guarantees, requiring an Edge/Fog computing approach. Additionally, users often require specific guarantees in the form of Service Level Agreements (SLAs) for storage services. To address these problems, we propose QoS-enabled Fog Storage Services, implemented as containerised storage services, orchestrated across the Things-to-Cloud computing continuum. (2) Method: The placement of containerised data storage services in the Things-to-Cloud continuum is dynamically decided using a novel Pareto-based decision-making process based on high availability, high throughput, and other QoS demands of the user. The proposed concept is first confirmed via simulation and then tested in a real-world environment. (3) Results: The decision-making mechanism and a novel SLA specification have been successfully implemented and integrated in the DECENTER Fog and Brokerage Platform to complement the orchestration services for storage containers, thus presenting their applicable value. Simulation results as well as practical experimentation in a Europe-wide testbed have shown that the proposed decision-making method can deliver a set of optimal storage nodes, thus meeting the SLA requirements. (4) Conclusion: It is possible to provide new smart applications with the expected SLA guarantees and high QoS for our proposed Fog Storage Services.

Multi‐party smart contract for an AI services ecosystem: An application to smart construction

AbstractVarious smart applications, such as in the domain of smart construction, require the use of artificial intelligence (AI) based services. In order to support such environments, various AI/knowledge service provider and consumer ecosystems have started to emerge. Within such ecosystems, the goals are to improve the quality, reliability, dependability in terms of governance and trust in the data which is exchanged among the various actors, which must be supported by specific business models. This work introduces a novel multi‐party smart contract (SC) that is designed to address the above mentioned goals. Specific service level agreements that illustrate the interactions among the AI service providers and consumers are also presented. The developed multi‐party SC supports different pricing schemes, which are analyzed in detail against the goals of the study.

Adapted smart home services based on smart contracts and service level agreements

SummaryIn smart home systems (SHS), devices intercommunicate to create an intelligent environment that can monitor the inhabitant's health state and provide adapted services. However, existing health monitoring systems (HMS) do not provide adapted services to the patient autonomy degree. Furthermore, in these critical systems, the Quality of Service (QoS) aspect is very important; therefore, service level agreements (SLA) are the best solution to define and guarantee the expected QoS levels, nevertheless, existing SLA specification languages lack expressiveness in terms of user preference specification, dynamic service management and pricing. In this work, we propose an elderly health state‐aware SHS to offer adapted services according to the elderly health state, it is based on three main parts: (a) the functional autonomy measurement system (SMAF) for calculating the inhabitant's profile or autonomy degree, (b) domain‐specific language (DSL) for SLA that aims to increase patient‐awareness through the use of preferences, facilitate the SLA management using microservices, and manage the QoS dynamically using multilevel SLA (ML‐SLA) concept, and (c) smart contracts for the provision of adapted services and the verification of SLA terms.

RE_BBC: Requirements Engineering in a Blockchain-Based Cloud System: Its Role in Service-Level Agreement Specification

The cloud has several security and trust issues with the third-party provider. The blockchain-based cloud (BBC) system is an emerging technology that promises safe storage of big data on a cloud. The development of such a system needs requirements engineering (RE) in determining the requirements based on service-level agreements (SLAs). RE can provide a functional process to model and specify a SLA-based smart contract. The RE process for BBC ensures that the resulting SLA specifications are consistent, accurate, complete, verified, and validated. The RE process responds to the many challenges of the BBC and determines a novel direction to provide efficient and quality development of blockchainbased applications.

Service level agreement specification for end‐to‐end IoT application ecosystems

SummaryWith an ever‐increasing variety and complexity of Internet of Things (IoT) applications delivered by increasing numbers of service providers, there is a growing demand for an automated mechanism that can monitor and regulate the interaction between the parties involved in IoT service provision and delivery. This mechanism needs to take the form of a contract, which, in this context, is referred to as a service level agreement (SLA). As a first step toward SLA monitoring and management, an SLA specification is essential. We believe that current SLA specification formats are unable to accommodate the unique characteristics of the IoT domain, such as its multilayered nature. Therefore, we propose a grammar for a syntactical structure of an SLA specification for IoT. The grammar is built based on a proposed conceptual model that considers the main concepts that can be used to express the requirements for hardware and software components of an IoT application on an end‐to‐end basis. We followed the goal question metric approach to evaluate the generality and expressiveness of the proposed grammar by reviewing its concepts and their predefined lists of vocabularies against two use cases with a considerable number of participants whose research interests are mainly related to IoT. The results of the analysis show that the proposed grammar achieved 91.70% of its generality goal and 93.43% of its expressiveness goal.

CART, a Decision SLA Model for SaaS Providers to Keep QoS Regarding Availability and Performance

Cloud systems are becoming a powerful tool for business. The evidence of the advantages of offering infrastructure as a service (IaaS), platform as a service (PaaS), or software as a service (SaaS) is overwhelming. Therefore, for SaaS providers, it is essential to know the virtual resources required to optimize the service offered and to keep the quality of service (QoS) at the desired levels. This paper presents an analytic model cloud availability and response time (CART) for obtaining the best tradeoff between performance, cost, and availability in a cloud system aimed at providing software as a service. The model aims to guarantee the predetermined availability and response time (RT) agreed with customers in a service-level agreement (SLA) contract while minimizing the cost of the system. A client-transparent error recovery strategy has been considered along with a Poisson traffic model. A sensitivity analysis of the simulated and real workloads is presented to study how a specific SLA influences the cloud service performance regarding the guaranteed RT and availability. The results corroborate the goodness of the model proposed, adjusting the real system accurately. Furthermore, the obtained results provide useful guidelines for cloud or Web-server designers.

Future integrated communication network architectures enabling heterogeneous service provision

Abstract. This paper summarizes expectations and requirements towards future converged communication systems denoted by 5th Generation (5G). Multiple research and standardization activities globally contribute to the definition and specification of an Information and Communication Technology (ICT) to provide business customers and residential users with both, existing and future upcoming services which demand for higher data rates and granted performance figures in terms of QoS parameters, such as low latency and high reliability. Representative use case families are threefold and represented as enhanced Mobile Broadband (eMBB), massive Internet of Things (mIoT), and Critical Communication, i.e. Ultra-Low Latency (ULL)/Ultra-High Reliability (UHR). To deploy and operate a dedicated network for each service or use case separately would raise the expenses and service costs to an unduly high amount. Instead provision of a commonly shared physical infrastructure offering resources for transport, processing, and storage of data to several separated logical networks (slices) individually managed and configured by potentially multiple service providers is the main concept of this new approach. Beside a multitude of other initiatives the EU-funded 5G NORMA project (5G Novel Radio Multiservice adaptive network Architecture) has developed an architecture which enables not only network programmability (configurability in software), but also network slicing and Multi Tenancy (allowing independent 3rd parties to offer an end-to-end service tailored according to their needs) in a mobile network. Major aspects dealt with here are the selectable support of mobility (on-demand) and service-aware QoE/QoS (Quality of Experience/Service) control. Specifically we will report on the outcome of the analysis of design criteria for Mobility Management schemes and the result of an exemplary application of the modular mobility function to scenarios with variable service requirements (e.g. high-terminal speed vs. on-demand mobility or portability of devices). An efficient sharing of scarce frequency resources in new radio systems demands for tight coordination of orchestration and assignment (scheduling) of resources for the different network slices as per capacity and priority (QoS) demand. Dynamicity aspects in changing algorithms and schemes to manage, configure, and optimize the resources at the radio base stations according to slice specific Service Level Agreements (SLAs) are investigated. It has been shown that architectural issues in terms of hierarchy (centralized vs. distributed) and layering, i.e. separation of control (signaling) and (user) data plane will play an essential role to increase the elasticity of network infrastructures which is in focus of applying SDN (Software Defined Networking) and NFV (Network Function Virtualization) to next generation communication systems. An outlook towards follow-on standardization and open research questions within different SDOs (Standards Defining Organizations) and recently started cooperative projects concludes the contribution.

Energy-Spectral Efficiency Tradeoffs in 5G Multi-Operator Networks With Heterogeneous Constraints

Along with spectral efficiency (SE), energy efficiency (EE) is a key performance metric for the design of 5G and beyond 5G (B5G) wireless networks. At the same time, infrastructure sharing among multiple operators has also emerged as a new trend in wireless communication networks. This paper presents an optimization framework for EE and SE maximization in a network, where radio resources are shared among multiple operators. We define a heterogeneous service level agreement (SLA) framework for a shared network, in which the constraints of different operators are handled by two different multi-objective optimization approaches namely the utility profile and scalarization methods. Pareto-optimal solutions are obtained by merging these approaches with the theory of generalized fractional programming. The approach applies to both noise-limited and interference-limited systems, with single-carrier or multi-carrier transmission. Extensive numerical results illustrate the effect of the operator specific SLA requirements on the global spectral and EE. Three network scenarios are considered in the numerical results, each one corresponding to a different SLA, with different operator-specific EE and SE constraints.

IOStack: Software-Defined Object Storage

As the complexity and scale of cloud storage systems grow, software-defined storage (SDS) has become a prime candidate to simplify cloud storage management. Here, the authors present IOStack, the first SDS architecture for object stores (such as OpenStack Swift). At the control plane, the provisioning of SDS services to tenants is made according to a set of policies managed via a high-level domain-specific language (DSL). Policies can target storage automation or specific service-level agreement (SLA) objectives. At the data plane, policies define the enforcement of SDS services, namely filters, on a tenant's requests. Moreover, IOStack is a framework to build a variety of filters, ranging from general-purpose computations close to the data to specialized data management mechanisms. Experiments illustrate that IOStack enables easy and effective policy-based provisioning, which can significantly improve the operation of a multitenant object store.

Monitoring Plane Architecture and OAM Handler

The increase of new services such as content distribution and interdata center connectivity poses new requirements on the control and management of next generation networks. The application-based network operations (ABNO) is emerging as a paradigm integrating control and management functions for different types of services. Key functionalities lie in the ABNO operation, administration, maintenance (OAM) handler which is responsible for the verification and the actual maintenance of network services following specific service level agreements. The OAM handler collects and correlates alerts about potential problems and triggers actions to preserve services in case of failures or degradations. In this paper, a hierarchical monitoring architecture is presented. The architecture is proposed by building on the OAM handler functionalities. Monitoring information can be filtered and correlated at each hierarchical level guaranteeing high scalability of the management plane. Actions can be taken at each hierarchical layer based on the type of failure and of affected service. Measurements on a commercial systems are carried on to identify the generated alarms upon failure. Then, simulations show the high scalability achieved by the proposed architecture.

클라우드 서비스 브로커를 위한 소프트웨어의 서비스 수준 합의 명세 모델과 중개 방법

SLA (Service Level Agreement) is an essential factor that must be guaranteed to provide a reliable and consistent service to user in cloud computing environment. Especially, a contract between user and service provider with SLA is important in an environment using a cloud service brokerage. The cloud computing is classified into IaaS, PaaS, and SaaS according to IT resources of the various cloud service. The existing SLA is difficult to reflect the quality factors of service, because it only considers factors about the physical Network environment and have no methodological approach. In this paper, we suggested a method to specify the quality characteristics of software and proposed a mechanism and structure that can exchange SLA specification between the service provider and consumer. We defined a meta-model for the SLA specification in the SaaS level, and quality requirements of the SaaS were described by the proposed specification language. Through case studies, we verified proposed specification language that can present a variety of software quality factors. By using the UDDI-based mediation process and architecture to interchange this specification, it is stored in the repository of quality specifications and exchanged during service binding time.

A design space for dynamic service level agreements in OpenStack

This paper does a systematic review of the possible design space for cloud-hosted applications that may have changing resource requirements that need to be supported through dynamic service level agreements (SLAs). The fundamental SLA functions are reviewed: Admission Control, Monitoring, SLA Evaluation, and SLA Enforcement - a classic autonomic control cycle. This is followed by an investigation into possible application requirements and SLA enforcement mechanisms. We then identify five basic Load Types that a dynamic SLA system must manage: Best Effort, Throttled, Load Migration, Preemption and Spare Capacity. The key to meeting application SLA requirements under changing surge conditions is to also manage the spare surge capacity. The use of this surge capacity could be managed by one of several identified load migration policies. A more detailed SLA architecture is presented that discusses specific SLA components. This is done in the context of the OpenStack since it is open source with a known architecture. Based on this SLA architecture, a research and development plan is presented wherein fundamental issues are identified that need to be resolved through research and experimentation. Based on successful outcomes, further developments are considered in the plan to produce a complete, end-to-end dynamic SLA capability. Executing on this plan will take significant resources and organization. The NSF Center for Cloud and Autonomic Computing is one possible avenue for pursuing these efforts. Given the growing importance of cloud performance management in the wider marketplace, the cloud community would be well-served to coordinate cloud SLA development across organizations such as the IEEE, Open Grid Forum, and the TeleManagement Forum.

Automatic test case generation for WS-Agreements using combinatorial testing

In the scope of the applications developed under the service-based paradigm, Service Level Agreements (SLAs) are a standard mechanism used to flexibly specify the Quality of Service (QoS) that must be delivered. These agreements contain the conditions negotiated between the service provider and consumers as well as the potential penalties derived from the violation of such conditions. In this context, it is important to assure that the service based application (SBA) behaves as expected in order to avoid potential consequences like penalties or dissatisfaction between the stakeholders that have negotiated and signed the SLA. In this article we address the testing of SLAs specified using the WS-Agreement standard by means of applying testing techniques such as the Classification Tree Method and Combinatorial Testing to generate test cases. From the content of the individual terms of the SLA, we identify situations that need to be tested. We also obtain a set of constraints based on the SLA specification and the behavior of the SBA in order to guarantee the testability of the test cases. Furthermore, we define three different coverage strategies with the aim at grading the intensity of the tests. Finally, we have developed a tool named SLACT (SLA Combinatorial Testing) in order to automate the process and we have applied the whole approach to an eHealth case study.

Cloud Service Management System for Innovative Clusters. Application for North-West Region of Romania

In order to stimulate and optimize the organization and management of innovative clusters from value chain perspective and guide their planning activities towards a differentiation strategy in which cluster members cooperate, we propose a Cloud Service Management System (CSMS) that provides IT services for these innovative clusters companies that can be customized for both enterprises with the associated clusters. Within such a system, actors begin to depend one on another and to take advantage of the local knowledge base. Each cluster is designed to have a different profile which will integrate all the companies mapped with it, with the objective of keeping the profile and data for each company. For the existing companies the idea is to migrate their services into the related cluster for integration within CSMS. Thus, our proposed CSMS will consider and meet different quality of services (QoS) parameters of each individual enterprise and service which will be included in specific Service Level Agreements (SLAs), after the negotiation between the cloud service provider and the CSMS. Realizing that technological progress is at the heart of regional development and decision-makers could support the development of technology clusters towards transforming them into regional innovative clusters, the application of our proposal aims to overcome existing bottlenecks in terms of business strategies and regional development policies in the North-West region of Romania.

Comprehensive Explanation of SLA Violations at Runtime

Service Level Agreements (SLAs) establish the Quality of Service (QoS) agreed between service-based systems consumers and providers. Since the violation of such SLAs may involve penalties, quality assurance techniques have been developed to supervise the SLAs fulfillment at runtime. However, existing proposals present some drawbacks: 1) the SLAs they support are not expressive enough to model real-world scenarios, 2) they couple the monitoring configuration to a given SLA specification, 3) the explanations of the violations are difficult to understand and even potentially inaccurate, 4) some proposals either do not provide an architecture, or present low cohesion within their elements. In this paper, we propose a comprehensive solution, from a conceptual reference model to its design and implementation, that overcomes these drawbacks. The resulting platform, SALMonADA, receives the SLA agreed between the parties as input and reports timely and comprehensive explanations of SLA violations. SALMonADA performs an automated monitoring configuration and it analyses highly expressive SLAs by means of a constraint satisfaction problems based technique. We have evaluated the impact of SALMonADA over the resulting service consumption time performance. The results are satisfactory enough to consider SALMonADA for SLA supervision because of its low intrusiveness.

Call center offshoring performance management

Purpose – This study aims to detect and mitigate opportunistic behavior in call centers through proper performance management and to provide companies considering outsourcing and/or offshoring their call center services with the important performance factors. Design/methodology/approach – The study introduces performance management as an important mediating process affecting BPO performance, and presents insights to the performance management of call centers, particularly related to detecting opportunistic behavior. Building from contractual and agency theory, KPI data from two different companies using two different pricing schemes was analyzed. The data represented 107 weeks under each contract type covering specific Service Level Agreement measures. Findings – The study indicates the importance of having in place a performance management system to manage BPO, and presents the notion of proxies to detect difficult to measure service level performance targets. The study confirms the existence of opportunistic behavior from the vendor side, and offers a structured method to detect and control for opportunistic behavior. Research limitations/implications – The research is limited to the call center outsourcing in the telecom industry. Price per call (PPC) and price per time (PPT) were the only pricing models studied. Practical implications – The study supports telecom companies that are interested in outsourcing their call center services with the important factors they need to consider during the outsourcing process, particularly in light of the vendor opportunistic behavior. Originality/value – The study contributes to the limited literature on performance management in BPO, and offers a structured method to test for the existence of opportunistic behavior.

SLA-driven dynamic cloud resource management

As the size and complexity of Cloud systems increase, the manual management of these solutions becomes a challenging issue as more personnel, resources and expertise are needed. Service Level Agreement (SLA)-aware autonomic cloud solutions enable managing large scale infrastructure management meanwhile supporting multiple dynamic requirement from users. This paper contributes to these topics by the introduction of Cloudcompaas, a SLA-aware PaaS Cloud platform that manages the complete resource lifecycle. This platform features an extension of the SLA specification WS-Agreement, tailored to the specific needs of Cloud Computing. In particular, Cloudcompaas enables Cloud providers with a generic SLA model to deal with higher-level metrics, closer to end-user perception, and with flexible composition of the requirements of multiple actors in the computational scene. Moreover, Cloudcompaas provides a framework for general Cloud computing applications that could be dynamically adapted to correct the QoS violations by using the elasticity features of Cloud infrastructures. The effectiveness of this solution is demonstrated in this paper through a simulation that considers several realistic workload profiles, where Cloudcompaas achieves minimum cost and maximum efficiency, under highly heterogeneous utilization patterns.

Investigations of an SLA Support System for Cloud Computing (SLACC)

Abstract Cloud Providers (CP) and Cloud Users (CU) need to agree on a set of parameters expressed through Service Level Agreements (SLA) for a given Cloud service. However, even with the existence of many CPs in the market, it is still impossible today to see CPs who guarantee, or at least offer, an SLA specification tailored to CU's interests: not just offering percentage of availability, but also guaranteeing, for example, specific performance parameters for a certain Cloud application. Due to (1) the huge size of CPs' IT infrastructures and (2) the high complexity with multiple inter-dependencies of resources (physical or virtual), the estimation of specific SLA parameters to compose Service Level Objectives (SLOs) with trustful Key Performance Indicators (KPIs) tends to be inaccurate. This paper investigates an SLA Support System for CC (SLACC) which aims to estimate in a formalized methodology – based on available Cloud Computing infrastructure parameters – what CPs will be able to offer/accept as SLOs or KPIs and, as a consequence, which increasing levels of SLA specificity for their customers can be reached.

Self-Management Principles in Autonomic Service Architecture Supported by Load Balancing Algorithm

This paper is about the role of a heuristic algorithm for load balancing that can be incorporated in Multi-Protocol Label Switching/ Differentiated Services (MPLS/DS) networks based on self-management principles for automated traffic configuration. Delivery of Quality of Services (QoS) differentiation according to specific service level agreements, Service Level Agreement (SLA), has to be in relation to resource management and bandwidth allocation, to ensure better end-to-end QoS provisioning and to avoid traffic congestion. To ensure simultaneous traffic flows with different priorities we need some load-balancing procedure. It could start much earlier than usual, possibly during SLA negotiation. If SLA creation is supported by load control mechanism it can ensure better performances of the network in the moment of service invocation. LSP (Label Switching Path) creation could be influenced by former contracted SLAs and such approach could be more effective than pure routing technique based on the shortest path algorithm (LSP creation in the moment of service invocation). So we propose application of heuristic algorithm tested on numerical examples with maximum M routers on the path and with differentiation of N service classes. Further, we introduced some capacity state restrictions in the process of network optimization, considering different algorithm options. We compared their performances, especially the algorithm complexity that is very important for efficient load control in huge networks.