What is cloud computing?

Cloud computing describes a new supplement, consumption and delivery model for IT services based on internet, and it typically involves the provision of dynamically scalable and often virtualized resources as a service over the internet.

Cloud computing is a distributed, computation model which offers managed, scalable. Secured, highly-available computation resources and software as a service. It abstract the complexity of software.

A cloud service has five distinct characteristics that differentiate it from traditional hosting.

a) On-demand service, this kind of services has little usage. Customer need to have a computer and internet access. They use part of the service as and when required and the service is fully managed by the provider.

b) Broad network access or Public cloud, here sells are made to everyone in the network. E.g., Amazon web services, Google app, Microsoft azure.

c) Resource Pooling (Location Pooling): users and applications are assigned to resources ad hoc, enabling the flexible use of a resource pool and higher utilization. The management of the resource pool is the responsibility of a cloud owner, which must meet all service-level guarantees associated with its cloud offering.

d) Scalable and Elastic: This is where your web infrastructure is hosted on multiple virtual machines (which may be elastic computing VMs) and is load balanced across these nodes. you then have the ability to expand and contract the number of nodes your site runs on as your traffic and business demands change.

e) Metered service: it's a proprietary network that supplies hosted services to a limited number of people. When provider uses public cloud for private clouding then it is known as virtual private cloud.

1) Infrastructure-as-a-Service(IaaS)

It compasses the hardware and technology for computing power, storage, operating systems or other infrastructure, delivered as of premises, on-demand services rather than dedicated as on-site resources. Because customer can pay exactly the amount the service they use. It is known as utility computing. Examples, Amazon elastic compute cloud, Amazon simple storage service.

2) Platform-as-a-Service(PaaS)

In the cloud is defined as a set of software and product development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider's platform.

3) Software-as-a-Service(Saas)

The vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

Cloud Computing Infrastructure Models

Built correctly, cloud computing provides significant cost advantages and provides users with the ability to become more agile and efficient in how they consume IT resources. With this said there are many options for enterprises to consider when making the decision to move to a cloud-based architecture and choosing to deploy on publically hosted clouds, private internal clouds or a hybrid environment. There are a number of considerations that go into selecting which model is appropriate for their needs, and each has some level of trade-off. Ultimately most enterprises will use a mix of models to solve more than one problem. For example, a project that might be in early development and test phases or only delivered for a temporary timeframe might be best suited for deployment in a public cloud where IT costs are lower and the capital expense for short term needs is minimized. At the same time, a more permanent project or one that has specific requirements around security, quality of service, or compliance might be ideally deployed in a private cloud or mixed hybrid environment.

Public Clouds

Public clouds are designed to be billed in a pay-as-you-grow model and are run by third party service providers, offering resources like compute power, network and storage as a service. One of the benefits of public clouds is that the amount of resource built into the service provider is fundamentally larger than a typical enterprise private cloud, meaning that the solution is designed to scale up and down based on demand. This model provides customers with a way to reduce operational risk and cost by providing a flexible, scalable service that is based on consumption.

Private Clouds

Private clouds are essentially built for exclusive use by one client, providing more control of data, security and quality of service than in a public cloud. Private clouds can both be built and managed within the walls of an enterprise or be 'hosted' externally through a service provider as a private cloud offering.

Hybrid Clouds

Hybrid clouds are a combination of both public and private cloud models. Hybrid clouds are designed to extend a private cloud with the available resources of a public cloud. This is most often seen when an enterprise anticipates planned workload spikes that generally only requires additional compute resources for a limited period of times. Hybrid models introduce the additional complexity of distributing applications and data between a public and private cloud and require strong efforts around open standards, common APIs and common infrastructure to make this model possible.

Regardless of implementation, enterprises are quickly realizing that the opportunity of this new model of computing fundamentally changes the way IT services are consumed within the enterprise and it is something they need to adopt today. Addressing the need for scale, quality of service, interoperability and open systems framework, has created a turnkey software stack that enables both enterprises and service providers to easily build and manage infrastructure clouds to accelerate the transformation to this new model of computing.

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