Cloud Service Models

The three service models defined by NIST are essentially a hierarchy:

� Cloud Software as a Service (SaaS). The capability provided to the consumer in this highest level is to use the provider�s applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a Web browser (e.g., Web-based e-mail). The consumer does not manage or control the underlying cloud infrastructure, including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.


� Cloud Platform as a Service (PaaS). The capability provided to the consumer in this intermediate level is to deploy onto the cloud infrastructure consumer-created or acquired applications developed using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure, including network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations.


� Cloud Infrastructure as a Service (IaaS). The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls).

Source of Information :  Implementing and Developing Cloud Computing Applications 2011