The Classifications of Cloud Computing

Although hype and conjecture has surrounded the concept of cloud computing for a long time now it is more than just a buzz term. With the increased uptake in portable devices such as smartphones, tablets and even laptops in the private consumer sector, as well as the resultant shift to home based work, business on the move and the use of personal devices in the workplace, the need for centralised, virtualised computing resources has surged in the last couple of years. In fact many of us use some form of cloud computing every day without really acknowledging it, whether it be webmail or online gaming.

What is Cloud Computing

In a very general sense, cloud computing describes any scenario where the user (the cloud client) is accessing computing resource from a virtualised environment (the cloud) via an internet connection. It can be though of in contrast to use of computing resource on the user’s local machine, local network or defined physical machines on other networks. Cloud services generally work by providers pooling together extensive physical resources (e.g., multiple servers across multiple data centers) to create a service which users can tap into as and when they need it (i.e., on demand) without the need to install anything locally, hardware or software.

Where a service is chargeable they can be offered on a pay as you go basis where the user only pays for what they actually consume, much like a utility like electricity where consumers can tap into the national grid (analogous to the internet) and pay simply for what they use.

There are a variety of different services that can be propositioned under the cloud computing umbrella term and that meet the above definitions, but they are broadly classified into three camps, depending on the provisioning of hardware and software resource.

Infrastructure as a Service (IaaS)

Usually shortened to IaaS, this classification of cloud computing incorporates services which offer virtualised physical computing resource, that is, resource such as server space, bandwidth, networking.

Salient examples of IaaS offerings include cloud hosting where websites are hosted on virtual server partitions which draw physical resource from a pool of multiple servers across multiple data centers. This idea can offer specific advantages such as

  • cost effective scalability – hardware resource can be accessed on demand so that the client only pays for what they use and they are not restricted by capacity
  • reliability – there is no single point of server failure as data is also duplicated (backed up) across multiple servers. If one server fails, the web site will not go offline

The areas of IaaS and cloud hosting can also include the concept of Virtual Data Centers (VDC) where a virtualised network of servers or computers is made available to the user instead of simply server space.

Platform as a Service (PaaS)

PaaS describes a proposition which includes the software that is required to create an operating environment which can be used by the client to create their own applications. In …