XaaS Decoded: Cloud Computing The Microsoft Way

Disclaimer: After finishing the post I realized it ended up being much longer that initially intended. Still, I don’t claim it’s an exhaustive analysis of cloud computing as it is today. It’s just a brief introduction into the matter, nothing more, nothing less. Here it goes…

There’s a question that pops up almost every time I have a discussion about cloud computing. That question is usually something like “So, what is XaaS exactly?” (XaaS is one of IaaS, PaaS, or SaaS). My latest post about the Tech’Ed keynote referred to some of these acronyms and triggered a new instance of this question from one of Genisoft’s business partners. So I guess it’s a good time to try to define a few things.

First of all, let’s start with the mother of all buzz-words (well, the most recent one to be more accurate): cloud computing. It has the same faith as many of its predecessors (BI, SOA, Web 2.0 – to name just a few) – it becomes so overloaded in terms of semantics that it reaches a point where it means so many things that it actually means nothing. Because it sounds cool and in the same time familiar, people tend to start using it to define things it was not really meant to define. To avoid the common pitfall of defining the meaning of buzzwords, I will try instead to focus on a few more precise concepts we can operate with.

Based on my experience so far, I find that when they are talking about cloud computing people usually refer (either directly or indirectly) to one of the following:

• IaaS (Infrastructure as a Service)
• PaaS (Platform as a Service)
• SaaS (Software as a Service)

This would be the first dimension of cloud computing. Let’s take a closer look…

IaaS is the basically virtualization offered as a service. Instead of spending on hardware, software licenses, storage, or network equipment, one can buy all these as a service. Simply put, your local iron gets replaced by a virtual one. You still have to do all the management and administration.

PaaS aims to abstract things more than IaaS. Instead of providing bare “logical” metal as a service, it delivers an application platform which one can use to implement apps. You don’t work anymore (at least not directly) with the typical concepts like server, OS, and so on. Some kind of abstraction is usually available which hides all these. Plus, several services are provided in order to shield you from “classical” infrastructure management. I’m thinking here about virtual machine provisioning, load balancing, guest OS patching, and the like. In a sense, PaaS offers you an OS for the datacenter where:

• Instead of the classical resources (CPU, GPU, memory, I/O) you are abstracting servers
• Instead of the classical OS abstraction layers you have some kind of agent infrastructure that is capable of abstracting the concept of a virtual server into a higher level element (like role for example)
• Instead of the classical OS API you have a set of complex services that you can use as building blocks for your apps

Finally, SaaS is at the highest level available where you get the direct services of an application online, without any kind of implementation effort. Opposed to IaaS, there’s no need to manage infrastructure. Opposed to PaaS, there’s no need to develop and/or manage applications. It’s simply there so you can use it.

The second dimension of cloud computing refers to the place where XaaS’s are deployed. Public and private are the most common places we’re talking about today. However, there are many folks out there (myself included) that don’t think exclusively in black and white. Perhaps intermediate approaches like community clouds (several entities share the infrastructure to get better privacy than with the public approach) or hybrid ones (the same entity has a mix of public/community/private approaches) are going to be at least as common as “pure” ones.

What’s interesting is what you get when you put these two dimensions in perspective:

	IaaS	PaaS	SaaS
Public	Has been around for quite some time, initially via hosting and more recently via virtualization	Available more recently from major vendors who have the strength to industrialize computing power and storage at a large scale	Has been around for quite some time. Gained a lot of momentum when major vendors decided to update complex on-premises apps and make them available online
Community	Interesting for areas like the public sector where different organizations (like government agencies) share the same needs and interest	An interesting option when you want more privacy than public PaaS but you’re not willing to risk alone	Lower license costs will probably drive this approach
Hybrid	Has been around for quite some time, as a natural combination between public and private	Most probably, that’s the way things will get started in the near future. It’s hard to imagine large organizations jumping directly into Public PaaS	Most probably we’ll encounter this one in organizations which will transit from on-premises implementations to public ones.
Private	Became quite popular once virtualization software and proper hardware support became available	Still at the “we’re talking about it” stage mostly. But not too far, as some of the vendors are now prepared to provide it. Interestingly, other major vendors who are a bit behind at the public game try to position their cosmeticized on-premises offers as Private PaaS.	In a sense, we’ve been doing that since the dawn of IT . In a more serious note, it’s probably going to be available in the form of software appliances.

With this Tech’Ed, Microsoft’s strategy is getting its final (public) touches. Seems that the guys in Redmond have pretty big plans as they intend to be a major player in all three areas (IaaS, PaaS, and SaaS). Their matrix looks like this:

As I mentioned in my previous post, Microsoft’s strategy and delivery look quite sharp and promising in all three areas. Consequently, this puts them in a position where they can claim the position of being one of the main players in cloud computing for the next decade. As always, time (and paying customers) will tell whether this huge undertaking will pay off or not.