The Cloud has become a new vehicle for delivering resources such as computing and storage to customers on demand. Rather than being a new technology in itself, the cloud is a new business model wrapped around new technologies such as server virtualization that take advantage of economies of scale and mufti-tenancy to reduce the cost of using information technology resources.

This paper discusses the business drivers in the Cloud delivery mechanism and business model, what the requirements are in this space, and how standard interfaces, coordinated between different organizations can meet the emerging needs for interoperability and portability of data between clouds.

Cloud Computing Overview

Recent interest in Cloud Computing has been driven by new offerings of computing resources that are attractive due to per-use pricing and elastic scalability, providing a significant advantage over the typical acquisition and deployment of equipment that was previously required. The effect has been a shift to outsourcing of not only equipment setup, but also the ongoing IT administration of the resources as well.

From Server Consolidation to Cloud Computing

The needed changes to applications, in order to take advantage of this model, are the same as those required for server consolidation – which had already been taking place for several years prior to the advent of the Cloud. The increased resource utilization and reduction in power and cooling requirements achieved by server consolidation are now being expanded into the cloud.

The role of server virtualization software
The new technology underlying this is the system virtual machine that allows multiple instances of an operating system and associated applications to run on single physical machine. Delivering this over the network, on demand, is termed Infrastructure as a Service (IaaS). The IaaS offerings on the market today allow quick provisioning and deployment of applications and their underlying operating systems onto an infrastructure that expands and contracts as needed to handle the load. Thus the resources that are used can be better matched to the demand on the applications.

How is all this managed?

IaaS offerings typically provide an interface that allows the deployment and management of virtual images onto their infrastructure. The life cycle of these image instances, the amount of resources allocated to these instances and the storage that they use can all be managed through these interfaces. In many cases, this interface is based on REST (short for Representational State Transfer) HTTP operations. Without the overhead of many similar protocols the REST approach allows users to easily access their services. Every resource is uniquely addressed using a Uniform Resource Identifier (URI). Based on a set of operations – create, retrieve, update and delete – resources can be managed. Currently three types of resources are considered: storage, network and compute resources. Those resources can be linked together to form a virtual machine with assigned attributes. For example, it is possible to provision a machine that has 2GB of RAM, one hard disk and one network interface.

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