A Cloud Definition, at Last

The variety of technologies in the Cloud makes the overall picture confusing and muddied. Besides, the terms SaaS, IaaS, PaaS … are all included in the Cloud, and can be used to split the cloud in cloud types. In this setting, we would find Infrastructure clouds (Amazon AWS or GoGRID like), Service Clouds (e.g. Google Apps), etc.

After long web searches, we were finally unable to find a formal academic definition of Cloud Computing really is. Actually, we were the ones to dig the Web and the Academic databases in order to find the bricks to build this definition.

Vaquero LM., Rodero-Merino L., Cáceres J., Lindner M. A Break in the Clouds: Towards a Cloud Definition. ACM Computer Communication Reviews. January 2009.

The article describes most of the Cloud definitions available so far to extract an overall definition. The article also pays attention to clarifying the differences between Grids and Clouds, which is a current source of confusion.

Clouds are a large pool of easily usable and accessible virtualized resources (such as hardware, development platforms and/or services). These resources can be dynamically reconfigured to adjust to a variable load (scale), allowing also for an optimum resource utilization. This pool of resources is typically exploited by a pay-per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs.

In other words, infrastructure Clouds (see a Cloud classification in the paper) are an advanced hosting platform, providing unlimited guaranteed scalability and freeing the Service Provider of costly tasks like Hardware management and maintenance (you only par for the resources you are actually using)

The partially EU-funded RESERVOIR project aims to extend the current Cloud capabilities by building an Open Source Federated Cloud Infrastructure.