As an alternative to the three-tier classification of cloud-based services: infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS), cloud computing can also be classified based on how are the underlying networks. implemented and accessed by the client. The following article provides an overview of the two main models of public and private clouds.
These models do not describe strict architectures, so a variety of configurations can be used to achieve each cloud computing model. Additionally, each model can be used to deliver each level of cloud service as mentioned above.
public cloud
When most people think of cloud computing, they think of a typical public cloud model in which the services offered are made available to public customers over a public network, usually the Internet. The accessibility of this model allows cloud services to be delivered to a mass market and for the provider to centralize/pool (and share) the physical computing resource needed to deliver the services; using virtualization where they need to establish operating environments. As a result, consumers and providers of public cloud services can benefit from considerable economies of scale to reduce their costs, as well as great scalability to respond to fluctuations in demand.
Public cloud services can often be free to the consumer, supported, for example, by advertising; however, when a charge does apply, they generally follow a pay-as-you-go (PAYG) model, meaning the consumer receives the computing resource they need as and when they need it and is only charged for what they use. Many of the cloud services that are more familiar to the general consumer, particularly software-as-a-service (SaaS) applications such as Google Docs (cloud-based ‘office’ applications), Gmail (web-based email ) or Dropbox (cloud storage), fall under the public cloud model.
For some consumers, the public cloud mechanisms that provide both cost savings and widespread availability can also lead to unwanted security vulnerabilities. While the security of these services is always improving, the fact that data is transferred over public networks and stored on shared physical and/or virtual servers may create obstacles for some customers using the public cloud to process sensitive data. They could look to private cloud services instead.
private cloud
Cloud customers who handle, process, or store sensitive data that they need to ensure that it remains private and secure, and who want to take advantage of some of the cost, availability, and scalability benefits that cloud computing typically offers, can use cloud computing services. private cloud as an alternative. to the public cloud.
The concept of private cloud is more difficult to define than public cloud, and there really is no strict definition. Private clouds are better categorized by some of the features they provide and the issues they address compared to public services, such as data security and ownership control (of servers, etc.), rather than the mechanisms that use. Of course, they’ll also showcase the tell-tale features of cloud computing in general: virtualization, instant scalability, PAYG charging, and automated resource allocation on demand.
Only one organization will be able to access the entirety of a private cloud (as opposed to multiple customers using services within the public cloud), and therefore some examples also allow the end-user organization to have control over the management of the cloud network and its whole. so they can tailor it to their own needs. However, the flip side of this control is that some of the cost savings generated by centrally managing public cloud services will be lost to private clouds. Instead, the service becomes closer in structure to a traditional LAN-based service, but with the aforementioned benefits of virtualization.
The server network itself can be hosted internally by the organization (as required by some regulatory bodies for sensitive data) or externally by a cloud provider (for example, a Virtual Data Center – VDC), but access will be restricted to the connections made behind the organization. firewalls To provide security and control, private clouds can employ certain technical features including closed server networks (not shared between clients), on-site server hosting, and leased lines to access these networks where they are hosted off-site .
