Introduction

Cloud computing is the distributed computing model that provides computing facilities and resources to users in an on-demand, pay-as-you-go model. The aim of the cloud computing model is to increase the opportunities for cloud users by accessing leased infrastructure and software applications anywhere and anytime. Therefore, cloud computing offers a new type of information and services that broadens the brand new vision of information technology (IT) services. The recent publicity surrounding cloud computing and at the same time the rise of smart mobile device help us to envision mobile cloud computing (MCC). MCC is a distributed computing model combining cloud and mobile computing. The objective of MCC is to enhance the computing and processing power of mobile devices by offloading tasks to cloud data centres. In the cloud, resources are hosted as software, database services, virtual servers (virtual machines), hardware, complete work flows, or complex configurations of distributed computing systems and applications for provisioning. These resources are provisioned as services and offered to the customer by the cloud service provider (CSP). Therefore, the CSP leverages cloud services in two forms: service and cloud provider. A cloud provider is the entity that offers and upholds a cloud and may offer internally developed services on the cloud. A service provider is an entity that crafts and preserves services for running and publishing in the cloud.

Service is a type of relation between the service provider and the service user. Therefore, service provisioning is the process of enabling the service customers to access the predefined resources and enjoy the required provisioned services. The resources are in the forms of hardware, software, computation, and storage. Essentially, the primary interaction between the customer and service provider depends on service provisioning. Thus, service provisioning plays a vital role for both the CSP and the cloud users. The CSP must provide the required and promised services, promised in the service level agreement (SLA), such as quality of services (QoS), availability, and pricing, and the services must satisfy the user requirements, such as on-demand availability, scalability, elasticity, security, and exact billing.

One of the objectives of service provisioning is fair comparison among the available services. Thus, the user can compare the different cloud service offerings according to their needs and prioritize them based on several predefined dimensions. However, the services provisioned to the user should meet certain service compliances and policies. Hence, the CSP assures the client of data protection, confidentiality, and security by complying with international compliance authorities, such as the National Institute of Standards and Technology (NIST), European Network and Information Security Agency (ENISA), health insurance portability and accountability act (HIPAA), and cloud security alliance (CSA). In addition, service provisioning should maintain the QoS, SLA, and user service requirements. All of these factors enable the user to compare the provisioned services, predict them, and rank them according to the user's needs to select the best available services. Therefore, from the customer's point of view, service provisioning is a very important aspect of cloud services.

This systematic review of cloud service provisioning enhances the knowledge for the general reader and new researchers. Hence, this review has a significant impact in this domain. Therefore, we reviewed the state-of-the-art of the art service provisioning objectives, essential services, topologies, user requirements, necessary metrics, and pricing; we synthesize and summarize different provision techniques, approaches, and models through a comprehensive literature review. A thematic taxonomy of cloud service provisioning is presented after the systematic review. Finally, future research directions and open research issues are identified.

The rest of this paper is organized as follows: Section 2 expresses the service provisioning background with definition, topology, and taxonomy. Section 3 discusses the objectives of service provisioning. Section 4 offers an overview of key areas of service provisioning. Section 5 introduces the service provisioning requirements and Section 6 deals with metrics. Section 7 focuses on several models, methods, and provisioning techniques. Section 8 explains the future research issues and challenges. Finally, Section 9 provides the conclusion. For better understanding for the general readers, we present a list of acronyms of commonly used words throughout this paper in the Abbreviations Section.