Cloud Computing is the next big thing in in Internet?s revolution. The “Cloud” represents “Internet” and “Cloud Computing” means “Internet Computing”. According to Wikipedia, 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.
In cloud computing you can use the pool of computing resources available like storage, applications, servers, services, and information etc. on pay-as-you-use basis. Since all the resources are available on the web, you need not invest your valuable time, money and efforts in hardware resources.
This increases agility, reliability, scalability and helps in reducing cost, maintenance efforts. Let?s have a look at cloud computing in more detail.
Characteristics of Cloud Computing
- On-demand self-service: User can request and configure services by themselves without requiring much help from service providers.
- Broad network Access: Services are available on all the Internet-enabled devices like desktops, laptops, PDAs, mobile phones etc.
- Resource Pooling: The service providers give shared access to computing power spread across multiple geographic locations – multi-tenancy
- Rapid elasticity: Elasticity can be defined as the ability to scale up or back depending on demand of resources. In cloud computing Customers can increase or decrease the demand of resources at will.
- Measured service: Customers pay only for the resources they have used. This billing system is based to the pay-as-per-use model.
Cloud Service Models
There are three types of cloud service models – Software, Infrastructure and Platform.
- Cloud Software as a Service (SaaS): The service providers provide customers the access to the software(s) already installed on the cloud. Customers don?t need to install or manage or buy any hardware for the software. He just has to connect it and use it. Customer controls only the application and not they underlying operating system, hardware or network infrastructure.
- Cloud Platform as a Service (PaaS): Customers are provided with operating system layer and application toolset. Customer controls the application and can also customize the application. He does not control or manage the underlying hardware or network infrastructure.
- Cloud Infrastructure as a service (IaaS): Customers are provided with the storage, networking and other fundamental computing resources. Here customer can deploy their operating systems and applications. They have control on the operating system, applications and storage and may also have limited control on networking infrastructure like firewalls etc
Cloud Deployment Models
There are four types of deployment models irrespective of service models:
- Public Cloud: The cloud infrastructure is owned by cloud service provider and is made available to general public or some large organization.
- Private Cloud: The cloud infrastructure is owned or leased by a single organization and is operated by the organization only.
- Community Cloud: The cloud infrastructure is owned and managed by a group of organizations who have shared interest like security requirements, policies or common mission.
- Hybrid Cloud: The cloud infrastructure comprises of two or more models (public, community or private).
Note: Private clouds are known as internal clouds and Public clouds are called as External Clouds