What is Cloud Computing? o Cloud computing:- is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet, users need not have knowledge of, expertise in, or control over the technology infrastructure in the “cloud” that supports them. o Cloud computing:- is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand, like the electricity grid. o Keywords:- Cloud Computing, Grid Computing, Internet as a Platform, On- demand Computing, Software as a Service.

What is Cloud Computing?

Types of cloud computing o Public clouds Public clouds are run by third parties, and applications from different customers are likely to be mixed together on the cloud’s servers, storage systems, and networks. Public clouds are most often hosted away from customer premises, and they provide a way to reduce customer risk and cost by providing a flexible, even temporary extension to enterprise infrastructure. o Private clouds Private clouds are built for the exclusive use of one client, providing the utmost control over data, security, and quality of service. The company owns the infrastructure and has control over how applications are deployed on it. Private clouds may be deployed in an enterprise datacenter, and they also may be deployed at a collocation facility.

Types of cloud computing o Hybrid clouds Hybrid clouds combine both public and private cloud models. They can help to provide on-demand, externally provisioned scale. The ability to augment a private cloud with the resources of a public cloud can be used to maintain service levels in the face of rapid workload fluctuations. This is most often seen with the use of storage clouds to support Web 2.0 applications. A hybrid cloud also can be used to handle planned workload spikes. Sometimes called “surge computing,” a public cloud can be used to perform periodic tasks that can be deployed easily on a public cloud.

Types of cloud computing

Architectural Layers of Cloud Computing o Software as a service (SaaS) Software as a service features a complete application offered as a service on demand. A single instance of the software runs on the cloud and services multiple end users or client organizations. (is simply order an application & start consuming in minutes. Salesforce.com is the best example for this category.) o Platform as a service (PaaS) Platform as a service encapsulates a layer of software and provides it as a service that can be used to build higher-level services.(is OS + Application Server stack like.Net framework, VS.Net, SQL Server etc. Best examples of PaaS are Microsoft's Azure & Google App Engine.)

Architectural Layers of Cloud Computing o Infrastructure as a service (IaaS) Infrastructure as a service delivers basic storage and compute capabilities as standardized services over the network. Servers, storage systems, switches, routers, and other systems are pooled and made available to handle workloads that range from application components to high-performance computing applications.(is all about hardware, data storage, networking and bandwidth ( i.e. Server, Routers, Switches,….etc). Amazon and Rackspace are good examples.)

Architectural Layers of Cloud Computing

Cloud Computing Benefits o Reduce run time and response time. o Minimize infrastructure risk. o Lower cost of entry. o Increased pace of innovation. o Reliability, scalability, security and sustainability.

Cloud Computing Disadvantages o Cloud computing does not allow users to physically possess the storage of their data so it does leave responsibility of data storage and control in the hands of the provider. o Cloud computing has been criticized for limiting the freedom of users and making them dependent on the cloud computing provider, and some critics have alleged that is only possible to use applications or services that the provider is willing to offer. o Users had no freedom to install new applications and needed approval from administrators to achieve certain tasks. Overall, it limited both freedom and creativity.