What is a Cloud Service?

June 19, 2011

Depending upon various implementers’ perspectives, there seems to be much confusion in terms of what constitutes a cloud service. Some use the term application or software interchangeably with service. Others, such as enterprise architects and service oriented architecture (SOA) practitioners, describe a service as a set of related software functionalities, together with the policies that should control its usage [1].

Let us first examine what a service is. In its broadest sense, a service is accompanied by an agreement between the service provider and the service consumer. That agreement may be unspoken or even unwritten. For example, if you go to a café, there is an unwritten agreement that coffee will be served within a certain period and that coffee will meet with your expectations. It is no use ordering a latte and then getting an espresso instead; nor is it any use ordering your coffee and then being told to come back tomorrow to drink it after paying for it. Another aspect of a service is that it is all encompassing in the sense that pretty much everything is a service – even a product. A product, after all, is simply a composition of a number of services: someone had to excavate the raw materials, turn them into a finished product, market the product, transport and sell it to the end user. All those services, then, constitute the product.

In IT, service managers define a service as a collection of IT systems, components, and resources that work together to provide value to IT customers. This definition conforms to ITIL. An important element of this is that, in order to measure and agree upon the value received, two parameters are usually used to assess a service: cost and the service (or operational) level agreement. The service level agreement (SLA) is essentially a contract between the consumer and the supplier in terms of how quickly the service will be delivered (when), its quality (what) and scope (where and how much).

Next, let us examine the cloud. In a broad sense, it provides a level of abstraction to the user in that the user is shielded from the various stages and processes involved in providing the result. So if the user needed a computational platform, he would not need to worry about the operating system, the underlying hardware, the hardware’s power consumption, any storage needed for storing intermediate data, etc. And if the user needed a photograph being processed, then he would not need to worry about the type of software needed, the data being exchanged between various applications to process the image, etc. All he would care about is the cost per photograph and the SLA.

It is important to bear in mind that a cloud service need not necessarily be underpinned by software functionalities. It could equally well be driven by the platform or the infrastructure needs of the user. All cloud services share the common foundation of a business process being provided, whether manually, automatically by software, or indeed any other means. A cloud service could have some manual interaction as part of a workflow that integrates with software and so one can have a combination of functions that provide a service. Moreover, some business value needs to accrue as part of the service being consumed and this business need has to be reflected in a definition of a cloud service.

Therefore, a cloud service is the implementation of a business process, provided through a set of related functional components and resources together with policies that control its usage, and provides business value to its consumers.

The use of an output in terms of business value is required; it ensures that the service will have a utility cost and a benefit associated with it. Further, that cost (in terms of service consumed) and the benefit (as enshrined by a contract or an SLA), will be associated with the service. Finally, it is the business process that gets implemented by the service and can be composed of any type of resource, whether software, infrastructure or even human.


[1] http://en.wikipedia.org/wiki/Service_(systems_architecture); accessed 13-Apr-11.

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