Explain like I'm five · Cloud

What is a Cloud Service Model?

Cloud service models (IaaS, PaaS, SaaS), told as how much of a shared office building you choose to rent.

office, computers, software... I need it ALL at once!this building is the clouda brand-new company needs too many things at once

A brand-new company needs too many things at once.Office, power, computers, software — all of it.

building your own from scratchbuy land → build → wire power → buy furniture...months and a fortune, before you even openpreparing everything yourself means you're exhausted before you even start

Preparing everything yourself means you're exhausted before you even start.Building your own takes months and a fortune before you even open the door.

IaaS: bare shellPaaS: interior doneSaaS: move-in readythe cloud = this very shared office buildingrent exactly as much of this building as you need

The cloud = this very shared office building.Rent exactly as much of this building as you need.

IaaS = rent the bare shellonly power and plumbing come with it
PaaS = interior already donejust add your own desk (your app)
SaaS = a move-in-ready officetake the keys and start using it
Pay only for what you useoften metered, not a flat rent
who manages what — IaaS / PaaS / SaaSdata: always mine in all threeapp: the building's job only in SaaSOS, middleware, runtime: the building's job from PaaS onhardware and building: always the building's job

What you manage yourself depends on which you rent: IaaS, PaaS, or SaaS.The less you manage yourself, the more the building does for you.

fit one building too tightly and moving gets hard (lock-in)some still build their own, for security or rules — that's on-premises

Fit too tightly to one building's way, and moving elsewhere later gets hard (lock-in).Some companies still build their own, for security or regulation (on-premises).

In one breath

Cloud service models are three levels of how much of the building you rent: bare shell (IaaS), interior done (PaaS), or move-in ready (SaaS).

Split into IaaS (just infrastructure like servers and networking), PaaS (adds OS and runtime so you focus only on the app), and SaaS (ready-made software you simply use). From IaaS to SaaS, your management burden drops and your freedom drops with it. Every other page in this shared-office-building world is a story set inside this same building.

When grown-ups say it

Cloud computing
A shared office building where computing resources get rented. You rent servers, storage, and the like, exactly as much as you need.
IaaS (Infrastructure as a Service)
The bare-shell office. Provides only infrastructure like servers and networking.
PaaS (Platform as a Service)
The office with interior already done. Covers OS and runtime too, so you focus only on building the app.
SaaS (Software as a Service)
A move-in-ready office — just take the keys. You use finished software as-is.
On-premises
A building you construct yourself. Some keep their servers in-house for security or regulation.
Pay-as-you-go
Paying for what you use, instead of flat rent. Charges stop once you release a resource; leave it running idle and you still pay.
VM and Container
The private office and the partitioned desk. Two ways to divide the space in one server. → the private office and the partitioned desk
Serverless
A meeting room rented only by the hour. An extreme form where you don't even think about the server (the shell). → the hourly meeting room
Next story
The Private Office and the Partitioned Desk →
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