Three firms, three needs
A bank must run an old program on a very special setup. A start-up wants to launch a new website this week with two developers. A small shop wants email and a shared calendar and has nobody who knows computers.
The same cloud answer will not suit all three. Today you learn to choose.
Key words
| Word | What it means |
|---|---|
| IaaS | infrastructure as a service: you rent machines and look after the rest |
| PaaS | platform as a service: you rent a platform and look after your own app |
| SaaS | software as a service: you use a finished app |
| Lock-in | being tied to one provider because moving away is hard |
| Customise | to change something to suit your needs |
| Patch | a small update that fixes a fault or a weak spot |
| Operating system | the main program that runs a computer |
| Provider | the company that owns and runs the cloud |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can give advantages and disadvantages of IaaS, PaaS and SaaS and choose one for a case.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
IaaS gives control and more work
IaaS lets you choose the operating system and install any software. You can start and stop machines when you like, and you never buy hardware.
But you must patch the system, set up security and fix problems yourself. It needs skilled staff. And a machine left running costs money all night.
PaaS saves time but narrows the choice
PaaS lets developers write and release an app fast. The provider looks after the system, the updates and the scaling. There is nothing to patch.
But you must use the languages and tools the platform allows. You have less control, and moving to another provider can be hard. This is lock-in.
SaaS is the easiest and the least flexible
SaaS needs nothing to install or patch. You sign in from a browser, and updates arrive by themselves. It is the cheapest way to start.
But you can customise very little. Your data sits with the provider. You need the internet to work. A price per user can grow as the firm grows.
The three models compared
| Model | Advantages | Disadvantages |
|---|---|---|
| IaaS | Full control of the system. Flexible. No hardware to buy | Client patches and secures the system. Needs skills. Costs run on if left on |
| PaaS | Fast to build and release. No system to patch. Scaling is handled | Less control. Limited tools. Lock-in to one platform |
| SaaS | Nothing to install or patch. Works at once. Updates are automatic | Little customising. Data is held by the provider. Needs the internet. Per-user cost grows |
The cells students fill in are left blank in this preview.