The cloud what is it and how to use it? That has been the question of late. When we start talking about the cloud there are three prevalent models that have emerged — IaaS, PaaS, and SaaS.
Of these SaaS, Software as a Service, is probably the oldest of these categories. This model has the application and data hosted and maintained completely outside of the local data center (ie in the cloud). This model has existed even prior to the web, but became popular with the notion of ASP (Application Service Providers ) during the infancy of the commercialization of the Internet in the early-mid ninety. An example of this is Salesforce.com. They provide a hosted CRM (Customer Relationship Managment) system.
IaaS, Infrastructure as a Service, is the cloud model to take hold. An IaaS could be thought of as a virtual machine room with networking, compute, and data storage all in the cloud. It still require the traditional model of architects and administrators to manage the applications, data, systems, and networks. Amazon Web Services (AWS) is one example of an IaaS provider.
The new model to the cloud is PaaS, Platform as a Service. With this model, you deploy applications into the cloud rather than servers. The server with operating system and execution environments already installed and maintained, as well as the network and databases. It reduces the need for system and network administrators necessary to run a traditional network and server environment, and moves the focus on to developing and maintaining the data and applications. Windows Azure is an example of a PaaS provider.
There are some other ‘saS types like Desktop as a Service, Backend as a Service, and Information Technology Management as a Service that could be exampled, but these are more specific cases of the three models above.