Situation 1: I am looking
for a house. My first constraint, being a middle class man, obviously is money.
The House owner here is ready to give his house on rent to me. But demands more
than my budget. And this is a house which can accommodate more than 4 persons.
Now we both came to a deal:
- I shall share the house with 3 other persons.
- They shall share the rent.
Situation
2: I want a cycle, I want
it to be the latest, the best, but
only for a month. Here came the cycle salesman. He gave me a fair deal, a
decently modern cycle which I can own for myself just for 1 month after which I
have to give him back his cycle with usage charge for his service.
These transactions are pretty
common in our daily life. Do you understand these? Then you have understood CLOUD COMPUTING except that, replace the house and the cycle with hardware and software.
Everything
today is computerized. Even a small shop owner maintains the inventory in his
personal computer. If this is the case, consider a huge enterprise which has
umpteen branches and business process. But unlike a small shop owner,
enterprise requires powerful computers. This investment is not one time and these
systems require maintenance and continuous improvement over time. This lead to
the idea of providing these infrastructures (both software and hardware) as
services on a semi–permanent (rented)
basis where you don’t add physical assets and are provided with great flexibility and choice in your purchase.
This concept is known as Cloud computing.
Okay, Proper Definition:
Cloud computing is the way of providing
computing resources, both hardware and software as service on a rented basis to
users. The service providers take care of creating, updating, maintaining the
necessary infrastructures removing the burden from users. Based on different
computing resources, services include:
Infrastructure as a service (IaaS)
Entire systems (virtual
machines) will be provided to the users. Users can access the systems through internet.
Users are responsible for the software needed. Service providers charge based
on the resource allocated and consumed by the users.
Platform as a service (PaaS)
In this model entire systems
along with the operating systems and an environment to deploy application
software are provided. Eg: Google App Engine
Software as a service (SaaS)
While the above two models are
used by companies, this one is more common and are used by us for our daily activities.
Software are created by service provider and deployed over the internet for
customers. End users use these services on a subscription basis. Eg: Email
providers like Yahoo, Gmail etc.
Storage as a service (STaaS)
As the name suggests storage is
provided getting rid of maintaining separate storage devices by the end users.
Eg: Windows Skydrive
Advantages:-
- No responsibility of creation, maintenance of systems.
- Easy implementation and economical.
- Flexibility in hardware and software i.e., pay as you use.
- Easy up-gradation to match current technology.
- Efficient usage of resources.
- Location independence i.e., accessible from anywhere.
Constraints:-
- Data security.
- Need for high speed internet connection (Essentially a big constraint for a country like ours).
- Universal standardization required which makes interoperability among providers difficult as of now.
- Dependent on service providers even for trivial applications.
