The Cloud: What’s It All About?
CLOUD LANDSCAPE
First, let’s look at the cloud landscape. Fig. 1 outlines one worldview of the cloud.
The National Institute of Standards and Technology (NIST) has defined three chief cloud topologies. Their definitions are well accepted by the industry.
IaaS: Infrastructure-as-a-Service—Resources of processing, storage, networks and other fundamental computing means where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications (app or apps).
PaaS: Platform-as-a-Service—This model is used by developers to create applications or services. Software tools are provided to enable the programming and deployment of the end product. The software stack differentiates this from an IaaS model.
SaaS: Software-as-a-Service—A service that runs applications on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface, such as a Web browser or other “app player” such as Adobe Flash.
These models offer services charged by usage; they are utilities for hire. ...
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