SaaS / PaaS / IaaS / HaaS

Question

I've read:

• IaaS, PaaS and SaaS Terms Clearly Explained and Defined and
• Cloud Computing – Demystifying SaaS, PaaS and IaaS

And I've got 2 questions:

1. Is Google App Engine considered PaaS or IaaS?

2. Is HaaS a subset of IaaS or is HaaS really just another name for IaaS?

Answer 1

This answer is from an article that I read "Toward a Unified Ontology of Cloud Computing"

1. As Google App Engine gives you a platform for better utilization of Google's resources, it can be considered PaaS. A good key for me is "Is this environment giving me some kind of API for better integration with a system? Then it's PaaS."

2. I read more than one definition about this, but nowadays what sounds better to me, and what the article writer says, is that HaaS, like CaaS (communication as a service) is a subset of IaaS: they create the infrastructure needed to perform IaaS, but it can't be considered essentially service like IaaS.

Here is a figure that describes what I'm saying:

Answer 2

Not sure about 1.

As for 2:

It is, ideologically, a subset. That is to say that in an IaaS I don't think it's necessary that the infrastructure elements treat the hardware as a service per se - it could be a proprietary OS/etc. dedicated for proprietary hardware.

The differentiator is that the OS could belong in an IaaS but not in an HaaS.

Answer 3

Google App Engine allows you to create our own application in Java, so it's a Platform As A Service. However, you only can use a restricted subset of Java, so it's actually closer to SaaS than to IaaS (which gives you a virtual machine and let you install whatever language stack or application you want).