Cloud allows to use applications as services over a network.It consists of a set of hardware and software resources which are used by the consumers of the cloud.The main difference between normal computing and cloud computing is that in the case of cloud computing you are running you applications off premises in a remote data centre while in the case of traditional computing your applications run in premises in your own data centre.
Cloud has the following characteristics:
- Elasticity resources can be provisioned or deprovisioned according to the consumers requirement.So from the end users point of view there are infinite resources.If you need 100 virtual machines you can easily add them yourself.If you want to remove any of the virtual machines later on you can do that as well.
- Self service User can himself add or remove resources as per his requirement rather than relying on IT staff.
- Metered User is billed according to the resource usage.
- Resource pooling Resources are shared by different users.This is also called as multi tenancy.
- Cloud is maintained by a cloud service provider.There are many big service providers such as Azure,AWS and Google.
There are 3 service models in cloud computing:
- IaaS or Infrastructure as a Service Users can provision processing,storage and networking resources.It also provides Hyper-V for creating virtual machines.
- PaaS or Platform as a Service Service provider provides main components such as OS,Databases.
- SaaS or Software as a Service Entire application stack is provided by the service provider.
Some of the advantages of cloud computing are:
- Lower setup costs If you are setting up an infrastructure then chances are that you don’t know exactly how many resources you would need.In such scenario instead of purchasing costly hardware you can use cloud and you will be billed only according to the usage.
- You don’t need to manage the infrastructure as it is managed by the cloud provider.