As the popularity of Cloud computing has grown, it has been discussed more and more in blog posts, papers, conferences and magazines. Therefore, many businesses have added the word cloud to their advertisements and they claim they provide cloud services but without making any changes to their old infrastructure which has resulted in frustration of end users and true cloud providers.
For a service to be categorised under the cloud model, based on NIST definition, it must have five essential characteristics: Broad network access, on-demand self-service, resource pooling, rapid elasticity, and measured service. These characteristics are described briefly below.
- Services must be available over the network accessible by different type of clients’ devices such as laptops, mobile phones and tablets.
- Based on users’ usage, the resources assigned to them must be scaled elastically without any interaction of the user.
- In general, users are not aware nor can manage the geographical location of resources, but they may be able to specify the high level of location based on their needs. For example, Amazon S3 services are available in the US, Europe, Asia pacific and a few more regions.
- Users of the system must be able to configure and deploy the service without assistance of service provider. For example, to start an instance of Amazon EC2, users can simply follow a set of pages and configure the amount of memory and computing units they are willing to pay for.
- The amount of resources, such as storage or processing hours, used by users is metered in accordance with the service type which can be monitored, controlled, and reported to both the service provider and the users of the service.