OVERVIEWING OF CLOUD COMPUTING
Cloud computing refers to the use of hosted services, such as data storage, servers, databases, networking and software over the internet. The data is stored on physical servers, which are maintained by a cloud service provider. Computer system resources, especially data storage and computing power, are available on-demand, without direct management by the user in cloud computing.
Classification
Instead of storing files on a storage device or hard drive, a user can save them on cloud, making it possible to access the files from anywhere, as long as they have access to the web.Cloud computing can be classified on the basis of various criteria some of these are as discussed below:
[A] Classification on the bases of Services provides by the host: Based upon this criteria, the services hosted on cloud can be broadly divided into :
IaaS PaaS SaaS
(a) Infrastructure-as-a-service (IaaS) : Infrastructure as a service or IaaS is a type of cloud computing in which a service provider is responsible for providing servers, storage and networking over a virtual interface. In this service, the user doesn't need to manage the cloud infrastructure but has control over the storage, operating systems, and deployed applications.Instead of the user, a third-party vendor hosts the hardware, software, servers, storage and other infrastructure components. The vendor also hosts the user's applications and maintains a backup.
(b) platform-as-a-service (PaaS): Platform as a service or PaaS is a type of cloud computing that provides a development and deployment environment in cloud that allows users to develop and run applications without the complexity of building or maintaining the infrastructure. It provides users with resources to develop cloud-based applications. In this type of service, a user purchases the resources from a vendor on a pay-as-you-go basis and can access them over a secure connection.
PaaS doesn't require users to manage the underlying infrastructure, i.e., the network, servers, operating systems, or storage, but gives them control over the deployed applications. This allows organizations to focus on the deployment and management of their applications by freeing them of the responsibility of software maintenance, planning and resource procurement.
(c) Software-as-a-service (SaaS) : SaaS or software as a service allows users to access a vendor's software on cloud on a subscription basis. In this type of cloud computing, users don't need to install or download applications on their local devices. Instead, the applications are located on a remote cloud network that can be directly accessed through the web or an API.
In the SaaS model, the service provider manages all the hardware, middleware, application software, and security. Also referred to as 'hosted software' or 'on-demand software', SaaS makes it easy for enterprises to streamline their maintenance and support.
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