Friday 1 May 2015

What is Cloud Computing? / Basics of Cloud Computing (IAAS, PAAS, SAAS, Public, Private, Community, Hybrid Cloud)

Hi Friends,
Almost all of us have heard the term "Cloud Computing", but very few of us know the exact basics of Cloud Computing. This post is for all those who wants to know what is cloud computing; how did it become popular; what is SAAS, PAAS, IAAS; what is public, private, community, hybrid cloud.
First let us know desktop computing, client-server computing, cluster computing, grid computing and cloud computing.

Desktop computing:
It is a computing(certain processing) on single system(desktop machine).

Client-Server computing:
It involves two types of systems. First is Client machine which has less amount of resourses(memory, processing). As the client machines have less amount of resourses, they request service(computing) from another machine which comparatively has higher amount of resourses. This another type of machine is called a Server. In this type of model, client machines can be one or more while server machine is considered to be just one.

Cluster computing:
In the above computing model, as I told, server machine is a single machine. Now assume a case in which many more client machines are requesting so much computing from a single server machine. In this case, for a single server machine, it is impossible to response these many client requests. Hence instead of a single server machine, a group of server machines is used. Such a group of server machines is called a Cluster. Computing on such a system is called Cluster computing.

Grid computing:
Assume there are several client-server systems which are physically(say region wise) separated. If all the servers from each client-server systems are connected together(means they are communicating with each other), then this group of client-server systems is called a grid. For e.g. in telecommunication, servers from different regions transfer certain information(e.g. roaming information) among them. Hence telecommunication is an example of grid computing model.

Cloud computing:
A combination of cluster and grid is called a Cloud. Henceforth a computing on a cloud is a cloud computing.

Big multinational companies like Amazon, Google, Microsoft had their big cloud spread all over the world which they built for their own use. Afterwards they started providing their infrastructure to others on rent(use and pay) basis and from there, a cloud computing was started on commercial basis.

Now let us see various Service models of cloud computing.

1. Infrastructure as a service(IAAS):
Providing resourses(memory, processing) as a service to the requesters is called Infrastructure as a service. Here cloud service providers only provide infrastructure(memory, computing) while users(requesters) has to deploy their own platform(OS or other environment) and also they have to deploy their own software applications.
Amazon is the biggest provider of IAAS.

2. Platform as a service(PAAS):
Providing environment or platform(e.g. any OS, JVM, compilers for php or python etc.) alongwith Infrastructure, as a service to the requesters is called as a Platform as a service. Keep in mind, when service providers are providing platform, definitely they are providing Infrastructure alongwith platform. Therefore PAAS=PAAS+IAAS.
Examples of a PAAS are Google App Engine, Microsoft Azure, all companies which provide hosting to your websites etc.

3. Software as a service(SAAS):
Providing ready made softwares or web applications to requesters as a service is called a Software as a service. When softwares(web applications) are provided as a service, definitely platform and infrastructure are provided alongwith. Therefore SAAS=SAAS+PAAS+IAAS.
Examples of SAAS are google services(gmail, youtube...), dropbox etc.

Now, we will see various cloud computing Deployment Models. Cloud computing deployment model is a way of using cloud computing. Let us see one by one-

1. Public cloud:
Providing same service to all users; is a Public cloud. For e.g. Google app engine service is same for all. There is no special privilege to particular user. Hence it is a public cloud.

2. Private cloud:
Some companies, they have their own special needs. They request a service from cloud service providers which is specially configured for them. Such service is called a Private cloud.

3. Community cloud:
When a group of companies have a similar needs, they together request a service from cloud service providers which is specially configured for them. Such service is called Community cloud.

4. Hybrid cloud:
Some cloud service providers provide all above services like public cloud, private cloud, community cloud. Such a combination of more than one services is called as Hybrid cloud.

Watch Following Youtube Video on Cloud Computing: