Cloud Computing

Different cloud service model

Cloud computing is a new class of network based computing which uses internet for communication and provides hardware, software and network service to clients. Some important characteristics are:

• On demand service
  
• Pay per use
  
• Elastic scalability
  

Service Models

Cloud computing service is offered to different groups of clients in different model.

The service models which are commonly deployed are:

• Software as a Service (SaaS)

An application or software is installed in the cloud. Users get the authorization to access the application from the client side.

 Consumers purchase the ability to access and use an application or service that is hosted in the cloud. These applications achieve scalability by cloning the task on to multiple virtual machines.  Cloud service providers manage the infrastructure and platform of the app.

• Platform as a Service (PaaS)

Consumers get access to the computing platforms. They can deploy their own software and applications in the cloud and need not think about the underlying hardware and software.

Windows azure is an example of PaaS.

• Infrastructure as a Service (IaaS)

 This service model offers physical or virtual machines and other resources which may include virtual-machine disk library, raw (block) and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs) software bundles etc.










 

Deployment Models

Depending on the users and requirements, different deployment model has been introduced.

• Public cloud
  
• Community cloud
  
• Private cloud
  
• Hybrid cloud
  

Characteristics of each model are discussed on the following section.       

• Public Cloud
  

The cloud infrastructure is accessible over a public network, such as the internet. Compared to other models, it offers significantly low costs as well as provides ultimate scalability with vast pool of resources, such reliability that individual users will experience no ill suffer. It is also flexible as we can use any service model such as SaaS, IaaS, PaaS in public cloud. The only problem may be the security problem.

Example: Amazon Elastic Compute Cloud (EC2), IBM' Blue cloud, Google AppEngine, Windows Azure Services Platform etc.

• Community Cloud
  

This infrastructure is dedicated to several organizations or communities with same interest. These communities have similar interest or goal to achieve. For example, a community cloud can aim to healthcare, IT solution etc. The cost is shared by the groups altogether. The cloud service is managed and secured by all participating organizations or a third party service provider.

• Private Cloud
  

This infrastructure is dedicated to a particular organization. It costs a lot, which can be met some big giant companies only. It offers higher security, privacy, full control on the service and improved reliability.

• Hybrid Cloud
  

This infrastructure is not any distinct concept, rather a combination of private and public cloud. Cost effectiveness of public cloud and improved security and privacy of private cloud is integrated here. Therefore, an organization can maximize their efficiencies  and cost effectiveness by employing public cloud services for the non-sensitive operations, such as their brochure site, while relying on a private cloud where security and privacy is required, such as for e-commerce portion.

Cloud computing is the future of computing system.  The advantage it offers with cost reduction of hardware and software, flexibility and scalability are really a great contribution to computing system. It has become very popular in this era.

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