An Overview of the Most Important Reference Architectures for Cloud Computing

Abstract

In this paper we have presented the main characteristics of the most important reference architectures designed for the cloud computing environment. Specifically, we have introduced the proposed architectures of the worldwide cloud computing companies like Cisco, IBM and VMware and we also had a look the National Institute of Standards and Technology (NIST) reference architecture which is the starting point for all proposed architectures in the field. As one would expect, the provider dependent reference architectures are written is such a way to suit the services and products of the company, while NIST's architecture is a more general model with more comprehensive architectural details that we highlighted in this article. In the end of the article we draw out some conclusions regarding the existing reference architectures for cloud computing.Keywords: Reference Architecture, Cloud Computing, Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure as a Service (IaaS).1IntroductionCloud computing is the new term used for utility computing, with emphasis offering IT resources over the Internet, in exchange of storing and operating resources locally. In the existing literature there are a plethora of different reference architectures, models and frameworks for cloud computing. Usually, a reference framework for cloud computing tries to offer the baseline that stands designing some interoperable cloud services and also their integration in the existing infrastructures of the Internet and private corporations. a regular basis, a reference framework should offer a draft or an architectural template that could be used by others that wish to adopt similar solutions. A reference model consists in explaining the concepts and relationships which sustain reference architecture, while the term reference framework refers to both (architecture + model of reference) [1]. A cloud computing architecture of a cloud like solution represents the structure of such a system. The term also refers to conceiving proper documentation of the architectural system of a cloud computing solution, facilitating the communication between the investors, taking initial decisions and it also allows the reuse of the design components and templates for other similar projects [2].A reference model of cloud architecture represents the abstracting of the cloud computing concepts and relationships, which can be used to train organizations and to create standards and guidelines in the purpose of aiding these application concepts. Groups of organizations like DMTF (Distributed Management Task Force) - are the initiators of a wiki page www.cloud-standards.org [3]. Cloud Security Alliance or Open Security Architecture develops reference models for cloud which can be used by different companies in the purpose of adopting new cloud technologies. Also, companies being active in the field (Cisco, IBM, VMware and others), also other federal agencies (GSA and others) are working some reference models of their own which have specific characteristics. Next we will present four of the most important reference architectures in the field:· Reference architecture CISCO - Cisco Cloud Reference Architecture Framework [4]· Reference architecture IBM - IBM CCRA [5]· Reference architecture National Institute of Standards and Technology (NIST) [6]· Reference architecture VMware - Architecting vCloud [7]2 CISCO reference architectureThe CISCO reference architecture is based the cloud definition provided by NIST, in which is stated, shortly, that a cloud represents IT services offered using a network. More precisely, the cloud is a model in which the IT resources and services are abstracted from the infrastructure and are provided on demand and at scale in an environment for multiple tenants. On demand stands for resources which can be supplied and billed for only when they are used. …