Cloud computing has reached an absolute frenzy in the IT media. It seems like the cloud is well on its way to displace the virtualization craze that started last summer and which has carried us through the past 12 months. As a result, I thought it would be an appropriate time to discuss how we think DaaS fits into the cloud phenomena.

Generally speaking, DaaS is about transforming desktops into a cloud service. However, there are already a number of different approaches to DaaS and they vary considerably. To start, I thought it would be helpful to classify the different versions of DaaS as they exist today. At the highest level, there are two general categories of DaaS – those based on local (or distributed) execution and those that leverage centralized (or remote) execution. This mimics the client computing taxonomy I helped create at Microsoft and which is outlined in the Flexible Desktop Computing white paper I co-authored.

So far, there’s really only one form of DaaS that’s emerged within the local execution category and that’s the approach being touted by MokaFive. However, it’s difficult to classify this form of DaaS as cloud computing because the processing happens locally. I prefer to call this model “cloud-stored desktops” because that’s what it is – virtual desktops stored in the cloud (by MokaFive) and downloaded on-demand to users’ PCs where they run locally. So the conclusion here is that DaaS with local execution is actually a form of cloud storage as opposed to a form of cloud computing.

That leaves us with the centralized execution approaches to DaaS. Here are the ones that come to mind:

1. Browser-based – Solutions where a desktop environment is delivered as a cloud service inside a web browser environment. These are usually some form of webOS or webtop, with the better known examples including Stoneware webOS and G.ho.st.

2. Shared services – Terminal/Presentation Server solutions that deliver a Windows Server desktop along with a selection of applications. Companies like Nasstar offer this type of cloud-based DaaS.

The last (of course) is Desktone DaaS. Our form of DaaS is based on the server-hosted desktop virtualization model of client computing (commonly known as VDI). In this approach, desktops are hosted within virtual machines that run on data center servers. Users interact with these environments through PC remoting technology and all the processing happens in the data center.

The key benefits that Desktone DaaS offers with respect to the other forms of cloud-hosted desktops are:

· Preserves the rich Windows client experience in the cloud – Desktone DaaS is the only form of cloud computing that provides an uncompromised Windows client experience. This is due to the fact that it leverages a hypervisor layer which enables the hosting of authentic Windows client OSes (i.e. Windows XP, Vista, etc.) Conversely, shared services environments offer a Windows experience that compromises application compatibility and user personalization. Browser-based solutions (webOSes/webtops) also compromise the user experience because they don’t natively support Windows applications. For enterprises with a large investment in Windows applications, this limitation is an absolute deal breaker.

· Supports a combination of on- and off-premise hosting models – It’s possible for the virtual infrastructure (VI) powering Desktone DaaS to be hosted either in a service provider or enterprise data center or both. We refer to these two operational models as hosted/cloud and managed CPE (customer premise equipment). Think of a private service provider cloud as spanning both environments. If the service provider has connectivity into the enterprise and owns and operates the virtual infrastructure, the solution can be delivered “as a Service” regardless of where the VI is hosted. The benefit here is the flexibility of servicing enterprises with different sets of requirements. For organizations with users that are more sensitive to latency (from a remoting performance perspective) or more concerned about compliance, the CPE model makes a lot of sense. However, enterprises who have very little data center capacity or whose user populations are more distributed may find the hosted/cloud model more appealing. In contrast, the other forms of DaaS only support the off-premise hosting model, which can be an issue for many types of organizations.

· Separates service provider and enterprise responsibilities – Desktone DaaS is the only model that allows clean separation between the responsibilities of the service provider and the enterprise. This, again, is a function of the hypervisor layer, which creates a clear boundary between the infrastructure powering the VM and what’s inside those VMs. The service provider is responsible for everything up to the virtual machine (i.e. servers, storage, virtualization software, etc.) and the enterprise is responsible for everything inside the VM (i.e. OS image/licensing, application packaging/licensing, user profiles, etc.) In addition, the private network connectivity between the service provider and the enterprise allows the service provider to host virtual desktops (either in their data center or the enterprise data center) while all application servers and data storage are still retained in the enterprise data center. This solves the age-old issue of data security that arises with the other forms of DaaS (and SaaS, for that matter). In those other models, application and user data normally have to be stored in the service provider’s data center which creates a major concern for many enterprises.

· Sustains the existing enterprise IT operating model – Enterprise IT has built its entire client computing operation around Windows. This impacts everything from application development, licensing and deployment to end-user support and training as well as many other aspects. The need to abandon all or part of that legacy is a major obstacle for other forms of DaaS, whether browser-based or shared services. Conversely, Desktone DaaS allows IT to continue with its current operating model while at the same time introducing many of the benefits provided by the cloud (i.e. anytime/anywhere access, subscription economics, etc.)

In summary, we believe that the Desktone DaaS form of cloud-hosted desktops is the model that best links the legacy of enterprise IT with the future. It’s an evolutionary (as opposed to a revolutionary) step that allows organizations to start experiencing the benefits of cloud computing without abandoning the large investment they’ve made in their existing IT infrastructure.