Making the economic case for cloud computing is not simple because you need to compare accurately the total cost of
owning your current systems (if any) with replacements in the cloud, and be able to predict confidently the expected return
on investment (if any); but the technological benefits are clearer. Public clouds afford on-demand access to a pool of rapidly scalable computing resources from anywhere.
Rapid scalability on demand
Two of the five essential characteristics of cloud computing are on-demand self-service and rapid elasticity, which speed up everything to do with IT provisioning. You can quickly provide new employees (temporary or permanent) with user accounts for your Software as a Service applications, and they can use any old personal computer to access it. You can develop new web-based business software applications using Platform as a Service without worrying about servers, firewalls, security or operating systems. And you can use Infrastructure as a Service to gain temporary access to seemingly unlimited computing power and data storage when you need it for as long as you need it.
Because they are web-based, your access to cloud computing services does not depend on the computer you are using – all you need is a web browser; and most SaaS solutions now support popular hand-held computing devices, too, through native browsers or downloadable applications. See Figure 2.1 for an example of the Salesforce.com iPhone application in action.
Assuming your cloud computing provider continues as a going concern then the services they provide will be effectively future proof. With Software as a Service (SaaS) and Platform as a Service (PaaS) you always get the latest software – updates are automatic. There are no costs for upgrading to the next version of your favourite application or development platform and it is in your supplier’s interest to ensure that their systems improve and remain competitive. Moreover, because the technologies are web-based they use standard information transfer protocols, facilitating connections to other web-based software. These benefits do not apply to Infrastructure as a Service (IaaS) where any business software applications are managed by you; but your system control panels and the underlying infrastructure will be kept up-to-date for you.