Skip to main content

Software as a Service

Summary

Objectives

By the end of this session you should be able to:

  • Explain what the cloud is, what existed before the rise of cloud services, and why the cloud was such a disruptive technology
  • Explain what Software as a Service is
  • Identify common SaaS products

Key Points

  • The cloud refers to servers that are accessed over the Internet, and the software and databases that run on those servers.
  • There are three main service models of cloud computing: SaaS, PaaS, IaaS
  • Instead of users installing an application on their device, SaaS applications are hosted on cloud servers, and users access them over the Internet.

Breakdown

Cloud Computing and Virtualisation

"The Cloud" is simply services running on the internet, abstracted away from any one computer. The term comes from the "cloud" that telecoms engineers would draw when representing the space between two networks, when they didn't want to draw (or didnt know) the specific connections in that space.

Cloud Computing is made possible through a technology called "virtualisation", which allows you to create one or more "virtual" computers on top of a physical computer. This allows you to "segment" one big computer and sell it as smaller units; it also allows you to install standard-size computers before you know how big a requested computer will be.

info

You can install virtualisation tools on most computers, which is really useful for learning. One such free tool is VirtualBox, which is very popular - and can allow you to install many operating systems to practice on without breaking your primary computer!

Traditional computing

Before cloud computing, individuals and organisations would have to purchase a physical computer if they wanted to run some software or store some data. As an example, it was common to buy large external hard disk drives to copy photos and other files to. This has now been almost completely subsumed by Cloud services such as Dropbox and Google Drive.

Service models

There are three models of cloud computing:

  • Software as a Service, in which software is hosted in the cloud and paid for by subscription.
  • Platform as a Service, where development teams build software and host it on developer-oriented cloud services.
  • Infrastructure as a Service, which allows operations teams to request virtual computers, storage and networking on-demand.

This model is not strict or strictly followed; new "*aaS" models have been invented over time, and many services don't cleanly fit into any one model.

SaaS

Software as a Service has largely replaced "boxed" products as a model for buying computer software. As an example, it used to be common to buy Microsoft Office from the shops - in a box, containing a CD that would install it. Microsoft Office is now a subscription service, and most computers no longer have CD drives!

An exception to this is computer games, although Netflix-style subscriptions have been growing over time. Generally, SaaS providers have become the dominant providers in their fields - people seem to prefer pay-as-you-go pricing to large up-front payments.