Cloud computing has attracted a lot of interest as more and more firms are moving to use cloud based computing services. In a recent column, Given that cloud computing is still evolving and maturing, I agree with Alistair’s points on the difficulties in defining cloud computing. The variety of definitions that are being discussed point to that as well. In this post, I would like to concentrate on the various characteristics and defining traits of cloud computing. Cloud pointers Before getting into the characteristics, there are some simple pointers to clarify. Cloud computing is one of a number of ways to have IT services delivered to your business. While it may involve some new technologies, it is not a new technology of itself. There are three standard delivery models in cloud computing, all of which are delivered over the internet. With each model, a business customer can have varying levels of technology and related administration services provided by the services provider; Software as a Service (SaaS) where a business gets access to a business system delivered as a service such as a payroll system, a sales system or an accounting system. The SaaS services provider is responsible for ensuring that the service is delivered according to the businesses requirements. The operation of the technology to run the software application is the responsibility of the services provider. Platform as a Service (PaaS) , where a business get access to a complete software platform, such as Microsoft Azure, SaleForce’s Force.com, and Google Applications, on which it can run it’s own business applications. In this scenario, the services provider is responsible for ensuring that the platform operates effectively and the business makes it’s own arrangements for each of the software applications running on the platform separately. Infrastucture as a Service (IaaS), where a business gets access to a particular stack of IT infrastructure services, including servers, databases, and a particular operating system. Service providers in this area include Amazon, Rackpace and local Irish vendors such as Opsource and C Infinity. The business can then operate and manage the technology stack as they wish; including the storage of data, the development and operations of software applications. When moving to cloud computing services,as with any IT project, there are some basic items to consider, some of which I discussed in a post on my blog. Characteristics of cloud services Pay as you go Traditionally, when businesses were purchasing infrastructure and software systems, there could be a relatively large upfront capital cost and potentially a relatively long turn-around time. An analogy would be if a business wanted to get access to electricity to power their offices and the only option was to purchase and install their own generator. They would have to decide not only on their current power requirements, but also on their likely future requirements.Instead, electricity is a utility and a business would approach an electricity services provider to source their requirements. It’s a similar situation with cloud computing, where the computing needs can be delivered like a utility. Costs are driven by usage and can be treated as current expenditure, rather than as capital. For example, with a software as a service offering, a business would pay for the number of users of the service with the cost per user moving according to the number of users at any point in time. Another example would be in the area of storage as part of an Infrastructure or Platform service, with a business paying for the amount of storage in use and as the storage requirements vary, the costs changes accordingly. Ease to scale up or down All businesses have times during their year when demand for services and products will peak and with every high, there is a low. One of the challenges previously with provisioning IT systems and infrastructure was while planning for peak demand, being left with redundant or under-utilised equipment during the periods of lower demand.With cloud computing services, it is easy to quickly request and have a specific service made available to cater for peak demand. Similarly when demand reduces, the specific service can be turned off. So cloud computing enables a business to quickly respond to any upturn or downturn in business.Typically, with cloud service providers, the business customer can request these changes through a web based management consule that enables them to not only request changes in services, but also to view what is already in use and how it is performing.With some service providers, it is possible to have a set of rules or thresholds related to the performance of the service that will trigger changes automatically to the service such as increases/decreases in storage, web server(s), or database capacity. Services are on-demand As you will have gathered from reading about the first two characteristics, all cloud services are available on-demand using the online console provided by the service provider. Users no longer have to undertake relatively long, somtimes paper based justification and/or request processes to request changes to the level of services. It all happens in a virtual world Virtualisation is a technology that is a key component in providing cloud based services, covering hardware, operating systems, storage, databases and software applications. In addition, as you will have read in the previous characterictics, the delivery of cloud based services happens in a virtual world, whereby requests for services, monitoring of services and payment for services happens online (i.e. virtually) which enables speed and agility. Services for my specific requirements – this is what I want With cloud based services, a business has the ability to customise a particular service to their specific requirements such as a specific workflow in a software application or a specific technology stack with an Infrastructure service. Businesses now have access to ‘bespoke’ services without being impacted by high upgrade and support costs when previously looking to have customised requirements delivered by way of on-premise or hosted solutions. I hope that the characterictics of cloud computing services are a little clearer and of assistance to you when reviewing how these services can benefit your business.