This paper discusses the concept of Cloud Computing to achieve a complete definition of what a Cloud is, using the main characteristics typically associated with this paradigm in the literature. More than 20 definitions have been studied allowing for the extraction of a consensus definition as well as a minimum definition containing the essential characteristics. This paper pays much attention to the Grid paradigm, as it is often confused with Cloud technologies. We also describe the relationships and distinctions between the Grid and Cloud approaches.

Cloud computing is currently the new buzzword in the Information and Communication Technology (ICT) industry. Early adopters in the market have already established quite stable and reliable offers of cloud-based services. From an economic perspective, each of these services is based on a certain business model. These models are in general used to describe the value-creating logic of organisations within a certain market, e.g., how a company or network of companies aims to make money and create consumer value with cloud offers. Thus, they should be the basis for every company's business. In this work, dynamic business models are introduced. Static, conventional models do not reflect the real world and lack substantial elements of changing market environments, whereas dynamic models express a time-variant view of the market. A key factor for success for the whole cloud-service market will be to avoid confusion about different offers, differentiators and functionality, which may occur during the (ICT-)traditional hype cycle, and could definitely blur essence and usefulness of market offers. The introduced dynamic perspective will allow pointing out the most important limitations and challenges at each hype phase that clouds have to face before becoming real, broad mainstream for enterprises.Reference to this paper should be made as follows: Lindner, M.A., Vaquero, L.M., Rodero-Merino, L. and Caceres, J. (2010) 'Cloud economics: dynamic business models for business on demand', Int.

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This paper discusses a business-oriented phenomenon called the Bullwhip Effect that affects the efficiency of traditional supply chains, identifying how it applies to the world of Cloud Computing. Comparisons are made between a traditional supply chain and the Cloud supply chain in order to observe how these relate with each other. In doing so, the occurrence of Virtual Machine (VM) Sprawl in Cloud data-centers is seen as a derivative of the Bullwhip Effect, such that the indicators and mitigation strategies from traditional supply chains could be applied in the context of Cloud supply chains. Indicators were derived for each of the problem areas, which can be seen as a sign of the VM Sprawl in a specific Cloud supply chain. Approachesto automation and monitoring are also considered, and a prototypical implementation is described.

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