Service-level agreement

About: Service-level agreement is a research topic. Over the lifetime, 4358 publications have been published within this topic receiving 75333 citations. The topic is also known as: SLA.

A framework for automated negotiation of service level agreements in services grids

Abstract: An important aspect of managing service-oriented grid environments is negotiation of service level agreements. In this paper we propose a framework in which we adopt the three-layer architecture of agent-based negotiation to the problem of service level agreement negotiation in services grids. We report on the first experience with an implementation of the framework in the context of the WS-Agreement specification provided by the Global Grid Forum and present lessons learnt when using this framework in a simple practical scenario.

SLA-driven capacity planning for Cloud applications

Abstract: Cloud computing paradigm has become the solution to provide good service quality and exploit economies of scale. However, the management of such elastic resources, with different Quality-of-Service (QoS) combined with on-demand self-service, is a complex issue. This paper proposes an approach driven by Service Level Agreement (SLA) for optimizing the capacity planning for Cloud applications. The main challenge for a service provider is to determine the best trade-off between profit and customer satisfaction. In order to address this issue, we follow a queueing network proposal and present an analytical performance model to predict Cloud service performance. Based on a utility function and a capacity planning method, our solution calculates the optimal configuration of a Cloud application. We rely on autonomic computing to adjust continuously the configuration. Simulation experiments indicate that our model i) faithfully captures the performance of Cloud applications for a number of workloads and configurations and ii) successfully keeps the best trade-off.

A Dynamic Reliability-Aware Service Placement for Network Function Virtualization (NFV)

Abstract: Network softwarization is one of the major paradigm shifts in the next generation of networks. It enables programmable and flexible management and deployment of the network. Network function virtualization (NFV) is referred to the deployment of software functions running on commodity servers instead of traditional hardware-based middle-boxes. It is an example of network softwarization. In NFV, a service is defined as a chain of software functions named service chain function (SFC). The process of allocating the resources of servers to the services, called service placement, is the most challenging mission in NFV. Dynamic nature of the service arrivals and departures as well as meeting the service level agreement make the service placement problem even more challenging. In this paper, we propose a model for dynamic reliability-aware service placement based on the simultaneous allocation of the main and backup servers. Then, we formulate the dynamic reliability-aware service placement as an infinite horizon Markov decision process (MDP), which aims to minimize the placement cost and maximize the number of admitted services. In the proposed MDP, the number of active services in the network is considered to be the state of the system, and the state of the idle resources is estimated based on it. Also, the number of possible admitted services is considered as the action of the presented MDP. To evaluate each possible action in the proposed MDP, we use a sub-optimal method based on the Viterbi algorithm named Viterbi-based Reliable Static Service Placement (VRSSP) algorithm. We determine the optimal policy based on value iteration method using an algorithm named VRSSP-based Value Iteration (VVI) algorithm. Eventually, through the extensive simulations, the superiority of the proposed model for dynamic reliability-aware service placement compared to the static solutions is inferred.

Database as a service (DBaaS)

Abstract: Modern Web or “Eternal-Beta” applications necessitate a flexible and easy-to-use data management platform that allows the evolutionary development of databases and applications. The classical approach of relational database systems following strictly the ACID properties has to be extended by an extensible and easy-to-use persistency layer with specialized DB features. Using the underlying concept of Software as a Service (SaaS) also enables an economic advantage based on the “economy of the scale“, where application and system environments only need to be provided once but can be used by thousands of users. Within this tutorial, we are looking at the current state-of-the-art from different perspectives. We outline foundations and techniques to build database services based on the SaaS-paradigm. We discuss requirements from a programming perspective, show different dimensions in the context of consistency and reliability, and also describe different non-functional properties under the umbrella of Service-Level agreements (SLA).