Types of cloud computing

Mell and Glance suggest a typology of three types of service models related to cloud computing.

·Software as a Service (SaaS) in which the customer uses the cloud provider's applications that are running on a cloud infrastructure. In this model, the virtual serve in the cloud is consolidated into a cloud virtual server that takes over the role of separate physical servers (e.g. HR, Sales, Sales Management, Facilities Management, Purchasing) typically residing in an organization.

·Platform as a Service (PaaS). In which the consumer has control over the deployed applications and possibly application housing configurations

·Infrastructure as a Service (IaaS) where the consumer can access and run an arbitrary list of software as required. In this service model the applicant will typically manage its application and data, with the cloud provider controlling runtime, middleware, operating systems, servers, storage and networking. An example is Amazon EC3.

There are many advantages:

·Ability to leverage web technologies coupled with standardization that makes it easy to access information by diverse users across multiple devices and at any time upon demand.

·Economies of scale - hardware utilisation. Typically, organizations have in the past had to configure their computing environment to handle peak processing demands, thus leading to significant under-utilization in off-peak periods.

·Economies of scale - data storage

·Elasticity to change IT infrastructure as required as the business grows and needs change

·Central management - updates and maintenance so latest version and functionality is always available.

·One-to-many applications thus more efficiently using of computing power