I picked up a comment last week that "SaaS is not the same thing as Cloud Computing" and thought I'd briefly take a look at this relationship.

Generally, I've noticed that there are at least three schools of thought on the words "Cloud Computing":

• Infrastructure oriented view: "just another name for utility computing"
• Software oriented view: "just another name for application service provision"
• Service oriented View "Everything as a service (XaaS) from now on"

I guess up until now it has really depended upon what angle an individual is coming from - traditionally infrastructure folks will always focus on the infrastructure while those with a software background operate on the application level, and never the twain shall meet. However, these two views are now combined under the service-oriented view: effectively "infrastructure as a service" and "software as a service" are two deliverables of Cloud Computing, as well as "everything else in between as a service".

Therefore my opinion would be that the terms "cloud computing", "utility computing", SaaS, Software + Services and all the other current buzzwords are different views of the same underlying phenomenon: the continual drive towards ubiquitous service orientation. Choose the one that suits to hang your business proposition upon.

Underlying this discussion is the difficulty of unbundling service value and "monetizing" the investments required for Cloud Computing. Software as a service (SaaS) requires Infrastructure as a Service (IaaS) to function. Conversely, IaaS requires SaaS to deliver end-value. (No-one's going to buy infrastructure without software to run on it!). No service-oriented business model would work without both components, and everything else in between.

Generally, when discussing cloud-based monetization models I think this wider concept is helpful: If "A" aaS requires "B" aaS and vice versa, then these services must be bundled together in order to make for a business. What you end up with is a symbiotic ecosystem of interdependent services bundled together to deliver end value.

Just one example from further up the food chain: "Search as a Service" is currently always bundled with "Targeted Advertising as a Service".