It’s always best to define a topic such as this, especially in light of the fact that “X as a Y” has been loosely connected to Cloud Computing in every way imaginable.  IT as a Service is no different.  Although several articles have been written about IT as a Service, the underlying core elements have not.  To really understand how we can approach something as monumental as the topic, we have to break it down into its core sub-elements, namely Software as a Service, Desktop as a Service and Platform as a Service.

Software as a Service (SaaS) - commonly defined by web based applications, this technology approach allows for the delivery of applications from a location separate from the local end device (PC, MAC, Mobile, etc).  This can be accomplished by utilizing a web browser to access the application or an application may be virtualized and transported to the end device.  In either case, the application is generally loaded in a central data center and delivered via LAN, WAN or open Internet connection.  In most cases web based applications are delivered over the Internet to the end device.  This gives rise to the notion that applications of the future will not be the sole responsibility of an Enterprise IT group.  Although the group may administer certain aspects of the applications and resulting end user data, the application itself is owned and core administration is done off-premise at the site of the application owner’s facility (usually known as a Independent Software Vendor or ISV).  Some applications are being re-developed for this environment.  Microsoft Office 2010 is a perfect example.  Whereas previous releases have required the expert administration of the local (on-premise) IT personnel, the design of Office 2010 is much different.

To seed the market and the new approach, Microsoft is offering up ‘light’ versions of Office 2010 free of charge, delivered over the open Internet.  The target audiences for this product are consumers and ‘light’ users who will only require a fraction of the capabilities of the Office products.  Other companies, such as and Citrix (GoToMeeting) have created this new paradigm.  Microsoft (and others) are merely following suit to what is an emerging mechanism for the delivery of applications.  Business owners and executives looking for a way to circumvent expensive IT infrastructure and personnel are looking at SaaS as a way to augment (or dissolve completely) their Information Technology groups.  There are technologies available today that enable locally run applications to be delivered in a SaaS model.

Desktop as a Service (DaaS) - One of the more confusing approaches under the IT as a Service mantra, DaaS recognizes that the ultimate goal is to connect a person to a machine.  In other words, an application is only a portion of what any user does on a personal computer, thin client or smart phone.  Where SaaS focuses on the individual application, DaaS focuses on the Individual.  DaaS allows not only applications to be delivered to an end device from a LAN, WAN or open Internet, but associates specific characterizations such as icon placement, desktop settings, interaction between desktop applications and interaction between an operating system and the applications.  There are many forms of DaaS including but not limited to Virtual Desktop Infrastructure (VDI).  In DaaS, anytime an end user wants access to his or her applications and data, the entire desktop is presented to them based on their individual (personalized) set up.  By using certain technical approaches, many of these characteristics can be delivered to the end user as well without the encumbrance of a direct connection with the operating system.  Client hypervisors are emerging to further arbitrate the hardware and associated operating systems from the applications and data themselves.  In parallel, server based computing has been a means to accomplish both the delivery of applications and the entire desktop.  The critical path to success for any DaaS approach is to understand the end users requirements and then deliver a technology approach that meets the demand.  DaaS implementations are becoming more commonplace but come with a cost.  By definition application delivery utilizes less bandwidth and server capacity than an entire desktop.  For service providers this is crucial as the offerings tend to be in the hundreds of thousands if not millions of subscribers from a single data center.

Platform as a Service (PaaS) - Once again PaaS has many definitions but seems to be concentrating around the notion that in order to develop structured environments (whether for Information Technology or for Software Engineering) there needs to be a mechanism to manage and control all of the pieces of the system.  As data centers (whether on-premise of off-premise) become more virtual in the way in which applications are loaded, delivered and managed a need is arising to create a platform by which to simplify the work and workloads.  This platform is really the orchestration of many different elements of a data center.  For instance, in the Applications Platform as a Service (APaaS) model, software development is accomplished as a virtual entity.  All of the available resources (memory, CPU, UI, O/S) are made available to the developer on virtual machines and software images stored for execution off-premise.  This allows for rapid development cycles and on-the-fly iterations of production code. 

In a production software delivery environment, the ‘platform’ is managed via a “universal management console” where virtual servers, O/S and applications can be stored, delivered and recovered with ease.  In either case, the PaaS approach is used to provide an endless means of flexibility and efficiency by arbitrating the physical hardware from the developer and the end user.  Many of the technologies required for this approach are already available but the System Level Management to easily manipulate the information and provide secure access are embryonic.  Service providers who will need agility and scale that a PaaS can offer will need a fully integrated solution to make this approach a reality.

When we roll all of this together we begin to see the possibilities and the challenges.  Each of these approaches brings benefits to what we have previously known as on-premise IT.  IT as a Service then is the combination of SaaS, DaaS and PaaS in order to deliver a simple, manageable, secure ecosystem which always has one common denominator…  The end user.  When considering buying or selling any or all of these approaches, the most beneficial way to start is with the end user.  Critical questions need to be asked in order to determine the right fit.  What are the end user needs?  When is it appropriate to use SaaS vs. DaaS?  How will a PaaS implementation be managed and what are the critical elements of the system?  Once this has been determined, a reasonable TCO/ROI model can be built with the end customer’s needs in mind.  Without answering these questions, we merely replace one technology with another and potentially the ability to exponentially expand a bad Information Technology approach.