Cloud computing is Internet based computing which derives the characteristics from client server model, Grid computing, Mainframe computers, peer-peer architecture where resources are shared.
This model is mainly adopted to avoid capital expenditures whereby the payment is only for the resources which you utilize. There are also theories where companies might save capital expenses upfront but in the long term they will be keep paying for the resources continuously which is not the case with capital expense.
Cloud computing Architecture:
A cloud can either be public or private. A public cloud is where the service is provided on demand for any clients. In a private cloud the service is provided to a single client. The combination of both public and private cloud is called virtual private cloud; here the private cloud is hosted in a public cloud.
In general cloud computing has a front end where the consumers log in and work on the backend which is hosted by the cloud service provider. The front end is nothing but the client computers and the applications required to access the cloud. The means of communication is the internet.
The cloud is the backend computing devices like servers, storage devices which together provide the computational services. There are set of computer which monitors the traffic, systems, and client requirements by following certain protocols which is known as middleware.
With this the cloud service provider should also make sure there is no data loss which is done by backing up of original data which is called redundancy.
Types of Cloud services:
- Infrastructure as a service: Infrastructure can be provided as a service. Amazon web services can be provided as example. Where the users application interface access the virtual servers and storage hosted by Amazon to read books online.
- Platform as a service: Platform in the cloud is a set of application or software which runs on platform which is hosted in the cloud. The users execute the application in the platforms hosted by the cloud provider through the platform or Application Program Interface (API). Googleapps is an example of platform services.
- Software as a service: In software as a service model provides both hardware and software infrastructure and provides a front end for the users to interact with the system through the front end portal. Microsoft exchange can be a good example where the exchange server is hosted in Microsoft cloud. MS Outlook is used to send and receive mails.
- Hybrid cloud: Here a part of the infrastructure is hosted inside the organization and the other part is hosted in a public cloud. The organization will use the public cloud for storage and use their infrastructure for other applications.
- Inter Cloud: It is the interconnection of clouds. This concept came into existence when there are no enough resources in a particular cloud. However Inter cloud concept has its own complexity like billing, QOS, interoperability, security.
- Privacy: Even though cloud computing offers great advantages and the need of the hour which is Green computing, there are few disadvantages with cloud computing, the company which hosts the cloud services can monitor the client systems as per their wish.
- Security: As the cloud is accessed through the internet there are security concerns. It is always secure whenever the data is in-house. Cloud security is a concept which is identical to network security and information security. There are security issues faced by the cloud service provider and also their customers. It is the duty of the cloud service provider to maintain the safety and security for the consumers.
- Availability and Performance: In addition to security the cloud service provider needs to make sure the system is available for its consumers. There are service level agreements (SLA) between the cloud service provider and the consumer which is related to the availability and performance.