Service Level Agreement in cloud computing: Taxonomy, prospects, and challenges

Cloud computing represents a distributed computing paradigm, offering hosted services via the internet on a pay-as-you-go basis. The Service Level Agreement (SLA) serves as a pivotal element of communication between Cloud Service Providers (CSPs) and Cloud Service Users (CSUs), detailing Service Level Objectives (SLOs) pertinent to service functionalities and Quality of Service (QoS). Within an SLA, service terms are formally documented in a contract between the CSP and CSU, ensuring that outsourcing customers establish an SLA with their vendors, thereby holding vendors accountable for financial consequences or payments should the set objectives not be achieved. In recent years, SLA methodologies in cloud computing have attracted considerable attention from the research community, with numerous strategies being developed to tackle challenges that may impede the efficient provisioning and management of QoS. This survey paper offers a comprehensive review of SLA techniques, presenting a detailed taxonomy based on their distinctive attributes. It discusses the evaluation parameters and platforms utilized in analyzing SLA approaches. Furthermore, the paper outlines design objectives and highlights open research issues that should be addressed when proposing new SLA techniques.