Cloud Computing Stack and Service Classification
The term ‘cloud computing’ is still interpreted as a reincarnation of grid computing. However, the latest concept of cloud computing aims at centralized provisioning of computational resources to multiple remote clients.
Clouds consist of pools of easily usable and accessible virtualized resources like hardware, development platforms, and services. This pool of resources is utilized by a pay-per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs. These resources can be optimally utilized according to a variable load scale. This paradigm has helped many businesses to cut down upfront infrastructure investments and maintenance costs.
In order to serve multiple customers, cloud computing offers on-demand self service over broad network access using a multi-tenant model. Here, the users have no control or knowledge of the physical placement of the data. Some of the important capabilities of cloud computing include its scaling capability to provide computational and storage resources in line with the demand. There are two other models, namely service models and deployment models that are important for understanding the cloud computing paradigm. The three widely adopted service models for cloud computing is mentioned below:
- Software as a Service (SaaS) – The user can use the provider’s applications deployed on a cloud infrastructure. In this case, only a limited set of configuration controls are made available.
- Platform as a Service (PaaS) – It offers a wider range of capabilities for the user, including the deployment of applications created and acquired by the user. However, the user does not have control of the underlying computing infrastructure.
- Infrastructure as a Service (IaaS) – The user can use the allocated resources to develop, deploy, and run arbitrary software. The user has the control over the provisioned resources; however, doesn’t have any control over the underlying cloud management infrastructure.
There are four generic types of cloud deployment models: private clouds, public clouds, community clouds and hybrid clouds. In the private clouds, the customer has the potential to fully control the hardware, network and software components, whereas in the latter case, the cloud deployment infrastructure limits the capabilities of the client to monitor and control the infrastructure.
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