Database Reference
In-Depth Information
Introducing PaaS, IaaS, and SaaS
In the evolution of cloud computing, there are the concepts of
Platform as a Service
(
PaaS
),
Software as a Service
(
SaaS
), and
Infrastructure as a Service
(
IaaS
).
PaaS is the cloud computing service that provides a computing platform and a solution
stack as a service. In PaaS, the cloud solution provider provides the operating systems,
databases, web servers, development tools, and other services that are required to host the
consumer's application. IaaS is at a level below the PaaS, as it provides the virtual (as well
as physical) machines, servers, storage options, load balancers, networks, and more basic
components. SaaS is at a higher level than PaaS, as it is the software distribution model in
which the applications themselves are hosted by a vendor or service provider and made
available to customers over a network, typically the Internet. Here is an image that shows
how Windows Azure supports IaaS and PaaS:
Depending on the cloud vendor, some of these terminologies may be termed slightly differ-
ent. While all cloud vendors support these components, they differ on the level of abstrac-
tion for these components. For example, Windows Azure will allow you to configure a vir-
tual machine in the cloud, while Salesforce clouds will not allow you to know which infra-
structure you are running on. The cloud vendor that is selected, as well as licensing, will
dictate your throttling level of transactions and the limitation of your resources. There will
be many limitations on resources and transactions as you are sharing resources that other
companies may be using as well and paying more to utilize those resources. In the cloud
world, consumption of resources and transactions is based on licensing. There are many re-
sources available by all cloud vendors to develop in their cloud, and there is a lot of help
available as their goal is to get you to utilize their cloud as much as possible as that is their
revenue stream.
