Cloud Computing: for my sophomore

Me: Do you know, what is cloud computing?

Yash: Are we doing some computing with clouds! :-)

Me: Nope.  Do you want to know about what is Cloud Computing?

Yash: Yes.

Me: Lets us make an analogy for Cloud computing.  OK, I have one.

I have few questions for you.  In which type of house, your friends John, Ram, Rita and Tom lives?

Yash: Means?

Me: Let me rephrase. Does your friends John, ram, Rita and Tom lives in independent single family houses or in apartment complex?

Yash: Each of these my friends live in independent single family houses.

Me: Ok. Does it also mean that each of your family is responsible for their water bill, electric bill, gas bill, maintenance of house, and front yard.

Yash: Yes. It is their house. It is their responsibility to maintain their houses.

Me: Understand. But is also means that they (or their parents) have to assign some minimum number of hours per week for upkeep of house.

Yash: Yes, they do.

Me: But in return of this sweat, they gate freedom to remodel their houses internally as well as externally. One import aspect we were missing – Huge money to purchase a house. Your friends had spent lot of money to purchase a house.

Yash: Yes. Provided they get permit from city.

Me: Sure. 

Me: Now assume all of your friends are living in a multi-story apartment complex on lease. In this case your friends (actually their parents) can offload some of the responsibilities of maintenance to apartment complex management like maintenance of green areas, shared lights, common walk ways, parking areas, building façade, etc. They need to worry only about consumables like electric bill, water bill, etc.

Yash: Yes.

Me: Also, in limited sense your friends can customize their houses – decoration etc. but cannot change basic structure of apartment.

Yash: Yes.

Me: Now, let us draw analogy. Independent houses are equivalent to computing environment where each enterprise (company) purchases computers, maintain them and get freedom to run any type of software program to run on those computers. This is traditional computing

Yash: Then, what is cloud computing?

Me: In case of multi-story apartment complex building, each tent is not owning any apartment but leasing it. Similarly in cloud computing environment, each tenant (company/enterprise) lease computers (computing power) and pays money on regular cycle. Tenant also pays money on consumables – like bandwidth used, number of users on computers, etc. So tenant does not pay any money to purchase of computers upfront but pays regularly for the resources consumed.  This is cloud computing.

Yash: So cloud computing essentially about leasing of computing power and paying money regularly instead of upfront.

Me: Yes, but not forget about offloading of day to day work to cloud provider (maintaining front yard, etc.) but limited flexibility to work within limits set by cloud computing provider.

Yash: This cool.

Me: Cloud computing provider ensures that one tenant does not encroach into another tenant’s house.

Yash: Yeah, it is must. No one likes that someone peak into their house.

Me: Depending upon level of flexibility to modify apartments, there are various types of cloud provider.

Yash: so what are various types of clod computing providers?

Me: Let us assume multi story apartment complex apartment’s management rents not the apartments but an area in building with defined boundaries. In this case tenants can design their own apartments.  These types of cloud computing providers are equivalent to Infrastructure as a Service (IaaS).

If multi-story apartment complex provider provides fully built apartments but allows sufficient flexibility to shift few walls here and there. These types of cloud providers are called Platform as a Service (PaaS).

In last case, fully built apartment is provided with only choice is left to lease of decoration. These types of cloud computing providers are called Software as a Service (SaaS).

Yash: I feel cloud computing can be summarized in one statement.

Me: which one?

Yash: As Spiderman said - With great power comes great responsibility.