A Guide to the Cloud Computing/SaaS/PaaS Environment

BEA Systems has put together a really nice visual rendering of the nascent world of on-demand technology services.  The on-demand environment currently includes the distinct service lines of cloud computing, software-as-a-service (SaaS) and platform-as-a-service (PaaS).

Peter Laird also provides these concise definitions of the key service lines.

Cloud Computing

Cloud computing refers to the virtualization of the data center, such that server machines are not thought of individually but as just a commodity in a greater collection of server machines. Cloud computing solutions in general strive to eliminate the need for an application deployer to be aware of the actual physical machines that are used to host the application. Some have called this idea “hardware as a service”.

Software as a Service (SaaS)

An application that is delivered through the SaaS model typically is done so:

• Over the internet,
• Remotely by a third party, with little/no opportunity to bring that application in-house
• With a usage-based pricing model

Platform as a Service (PaaS)

When a vendor offers a Platform as a Service, they are offering an integrated platform to build, test, and deploy custom applications. The PaaS is offered to you in a SaaS model (remote, usage-based). 

Core Cloud Services

After defining the 3 markets, there remains a set of solutions that contribute to all as fundamental building blocks. In other words, these solutions address cross cutting concerns.

You can read more on the industry player's map at Peter's blog here.