Sunday, March 9, 2014

What is cloud computing? (Introduction to cloud computing)

What is cloud?
Cloud computing is basically just a service. For example gmail is a cloud based service which comes under the category of Saas (software as a service).

Types of cloud
In a simplified view cloud can be broadly classified into the following three categories
Saas (Software as a service)
Paas (Platform as a service)
Iaas (Infrastructure as a service)

Saas is a service where you get a software to consume.
Consumers: The common man
Examples: Gmail, Google docs, Facebook, Microsoft Office 365

Platform as a service is one layer deeper than Saas. In Paas you get a ready made software development platform with SQL server, IIS web server and other softwares that you need to start writing applications.
Consumers: Developers
 ExamplesGoogle app engine, Microsoft Azure (Note Azure has both paas and iaas offerings).

Infrastructure as a service offers even more control than paas. In Iaas you use a self service portal where you fill in details such as how much RAM you need , how many CPUs you need, pick the iso image that you want to deploy on your VM and so on.
Consumers: Business within an organization, Developers, IT
Examples: Amazon Elastic Compute Cloud 

Remember here, to qualify as cloud it should be an automated service. If your IT department gives out virtual machines in your datacenter, that DOES NOT qualify as cloud. However if you can use a website to request VMs in your private datacenter, where the request can get completed in an automated manner, without any need for human intervention (except for approvals), then that could qualify as cloud.

Many people confuse between cloud and virtualization. Virtualization is NOT cloud. Virtualization is a component of the cloud.

Private and Public cloud
If you are using VMware cloud infrastructure to create a cloud service, where your data resides on your own servers, then that would qualify as private cloud.
If you use a third party service like Amazon EC2, where your data resides on somebody else's server, then that is a public cloud.

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