Establishing and Monitoring SLAs in complex Service Based Systems

In modern service economies, service provisioning needs to be regulated by complex SLA hierarchies among providers of heterogeneous services, defined at the business, software, and infrastructure layers. Starting from the SLA Management framework defined in the SLA@SOI EU FP7 Integrated Project, we focus on the relationship between establishment and monitoring of such SLAs, showing how the two processes become tightly interleaved in order to provide meaningful mechanisms for SLA management. We first describe the process for SLA establishment adopted within the framework; then, we propose an architecture for monitoring established SLAs, which satisfies the two main requirements introduced by SLA establishment: the availability of historical data for evaluating SLA offers and the assessment of the capability to monitor the terms in a SLA offer

SALMon: A SOA system for monitoring service level agreements

In this paper we present SALMon, a tool assessing the satisfaction of service level agreement (SLA) clauses by service-oriented systems. SALMon itself is organized as a service-oriented system that offers two kind of services: 1) the Monitor service that measures the values in execution time of dynamic quality attributes (like response time or availability), and 2) the Analyzer service that detects and reports violations of SLA clauses from the values obtained with the Monitor. The SALMon tool is highly versatile, allowing: 1) both active testing and passive monitoring as strategies, 2) different types of technologies for the monitored/tested systems (e.g., Web services, RESTful services), 3) agile definition of measure instruments for new quality attributes. The service-oriented nature of SALMon makes it scalable and easy to integrate with other services that need its functionalities.Postprint (published version

5G & SLAs: Automated proposition and management of agreements towards QoS enforcement

Efficient Service Level Agreements (SLA) management and anticipation of Service Level Objectives (SLO) breaches become mandatory to guarantee the required service quality in software- defined and 5G networks. To create an operational Network Service, it is highly envisaged to associate it with their network-related parameters that reflect the corresponding quality levels. These are included in policies but while SLAs target usually business users, there is a challenge for mechanisms that bridge this abstraction gap. In this paper, a generic black box approach is used to map high-level requirements expressed by users in SLAs to low-level network parameters included in policies, enabling Quality of Service (QoS) enforcement by triggering the required policies and manage the infrastructure accordingly. In addition, a mechanism for determining the importance of different QoS parameters is presented, mainly used for “relevant” QoS metrics recommendation in the SLA template

Web Service Reputation Evaluation Based on QoS Measurement

In the early service transactions, quality of service (QoS) information was published by service provider which was not always true and credible. For better verification the trust of the QoS information was provided by the Web service. In this paper, the factual QoS running data are collected by our WS-QoS measurement tool; based on these objectivity data, an algorithm compares the difference of the offered and measured quality data of the service and gives the similarity, and then a reputation evaluation method computes the reputation level of the Web service based on the similarity. The initial implementation and experiment with three Web services' example show that this approach is feasible and these values can act as the references for subsequent consumers to select the service

An SLA Support System for Cloud Computing

Abstract. Nowadays, even with the existence of many Cloud Providers (CP) in the market, it is still impossible to see CPs who guarantee, or at least offer, an SLA specification to Cloud Users (CU) interests: not just offering percentage of availability, but also guaranteeing 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 proposes the initial design and preliminary approach for an SLA Support System for CC (SLACC) in order to estimate in a formalized methodology -based on available CC 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

Identifying Test Requirements by Analyzing SLA Guarantee Terms

Service Level Agreements (SLAs) are used to specify the negotiated conditions between the provider and the consumer of services. In this paper we present a stepwise method to identify and categorize a set of test requirements that represent the potential situations that can be exercised regarding the specification of each isolated guarantee term of an SLA. This identification is addressed by means of devising a set of coverage levels that allow grading the thoroughness of the tests. The utilization of these test requirements would focus on twofold objectives: (1) the generation of a test suite that allows exercising the situations described in the test requirements and (2) the support for the derivation of a monitoring plan that checks the compliance of these requirements at runtime. The approach is illustrated over an eHealth case study

Furthering the Growth of Cloud Computing by Providing Privacy as a Service

The evolution of Cloud Computing as a viable business solution for providing hardware and software has created many security concerns. Among these security concerns, privacy is often overlooked. If Cloud Computing is to continue its growth, this privacy concern will need to be addressed. In this work we discuss the current growth of Cloud Computing and the impact the public sector and privacy can have in furthering this growth. To begin to provide privacy protection for Cloud Computing, we introduce privacy constraints that outline privacy preferences. We propose the expansion of Cloud Service Level Agreements (SLAs) to include these privacy constraints as Quality of Service (QoS) levels. This privacy QoS must be agreed upon along with the rest of the QoS terms within the SLA by the Cloud consumer and provider. Finally, we introduce Privacy as a Service (PraaS) to monitor the agreement and provide enforcement if necessary

Analysis of SLA compliance in the cloud: An automated, model-based approach

Service Level Agreements (SLA) are commonly used to specify the quality attributes between cloud service providers and the customers. A violation of SLAs can result in high penalties. To allow the analysis of SLA compliance before the services are deployed, we describe in this paper an approach for SLA-aware deployment of services on the cloud, and illustrate its workflow by means of a case study. The approach is based on formal models combined with static analysis tools and generated runtime monitors. As such, it fits well within a methodology combining software development with information technology operations (DevOps)

Formal Verification of Service Level Agreements Through Distributed Monitoring

In this paper, we introduce a formal model of the availability, budget compliance and sustainability of istributed services, where service sustainability is a new concept which arises as the composition of service availability and budget compliance. The model formalizes a distributed platform for monitoring the above service characteristics in terms of a parallel composition of task automata, where dynamically generated tasks model asynchronous events with deadlines. The main result of this paper is a formal model to optimize and reason about service characteristics through monitoring. In particular, we use schedulability analysis of the underlying timed automata to optimize and guarantee service sustainability

Service level agreements for the digital library

Digital libraries offer a massive set of digital services to geographically distributed library patrons. The digital services are commonly sourced from third-party service providers for charge. As externally sourced digital services are becoming prevalence, issues regarding their quality assessment are gaining critical importance. Unfortunately, sourcing digital services from external providers has brought with it stringent quality of service (QoS) demand from the library service users. Currently, there is no way for ensuring QoS between the digital service providers and the library management. In this paper, we propose service level agreements (SLAs) to capture the QoS requirements of the digital service users and the commitments, as well as adherence of the digital service providers