Three Service Models of Cloud

In cloud computing, everything is provided on a 'service' model.

For example, rather than the end user buying a physical server, mounting it on a rack, installing the hypervisor, creating the VMs, etc, the service provider offers all of this as a service.

There are a variety of services referred to as '___ as a Service' or '_aaS'.

The three service models of cloud computing are:

Software as a Service (SaaS)

The capability provided to the consumer is to use the provider's applications running on a cloud infrastructure. The applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g. web-based email), or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual applications capabilities, with the possible exception of limited user-specific application configuration settings.

Microsoft Office 365 is a popular example of SaaS.

Platform as a Service (PaaS)

The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services, 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 he deployed applications and possibly configuration settings for the application-hosting environment.

Examples include AWS Lambda and Google App Engine.

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, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).

Examples include Amazon EC2 and Google Compute Engine