Cloud service models – IAAS, PAAS and SAAS

Cloud service models – IAAS, PAAS and SAAS

Cloud computing is a generic term that applies to online services. Each user of cloud services will have different requirements based on their business needs, their resources and their level of technical expertise.
There are three service models to choose as your entry point into cloud computing. As with everything cloud, it is about choice and flexibility.

IaaS – Infrastructure as a service

Infrastructure is the base building block that your IT systems will be built on. Infrastructure includes server hardware, cabling, storage and bandwidth. Traditionally, companies would need a secure area in which to install their server and networking infrastructure. This would have to be environmentally controlled to maintain operating temperatures. Equipment would have to be requisitioned and installed and configured, monitored and maintained, replaced at the end of its life cycle. All of this is costly and time consuming.

By entering at the IaaS model, you are removing the responsibility for this to someone else. You are also removing most of the processes described above and without the lifecycle commitment that you have with on premise infrastructure. Network infrastructure can be added or removed in an instant, with many services charging by the hour. Capacity can be scaled up and down to handle seasonal adjustments in the business or specific projects. The responsibility for maintaining the equipment is passed on to your supplier and hardware upgrades are no longer your worry.

Entering at the IaaS model gives you flexibility over capacity and computing power as and when you require it.

PaaS – Platform as a Service

Platforms run on top of the underlying infrastructure. If you entered at the IaaS model then you will need to choose your platforms to run or develop your business applications on. Platforms will include operating systems, database providers, application servers and development platforms.

Platforms add value to the infrastructure and allow you to develop and host your in-house or bespoke applications on top.
There is a fine line between entering at the IaaS and PaaS level. For example, if you needed to provision a SQL database, it is important that the chosen platform runs on infrastructure that will handle capacity which will change as the application development cycle moves through development, testing and production.

SaaS – Software as a Service

This is the model that many will enter at when using cloud services. The infrastructure and platform are already provided by the software vendor and all you are responsible for is the use of the software. The software is run over the internet and so is immediately available for use and is typically paid for on a metered or subscription basis.
The supplier will apply updates and patches centrally so that you always have access to the latest version, eliminating in-house support costs.

The software becomes accessible wherever there is internet access and is delivered independent of platform or operating system. Application data is stored in the cloud and responsibility for backups is passed onto the supplier.
SaaS removes many barriers for technology adoption and expansion. Software can be evaluated, requisitioned and dropped without long term commitments or platform or capacity restrictions.


The level that you enter the cloud model depends on the level of control you require over computing power, capacity, platform dependence, level of application customisation. The service models allow you the flexibility and choice to setup exactly for your businesses needs with the comfort in knowledge that you can rapidly change if required.

Article written by

Alan Pratt

Alan Pratt (InfoEase Ltd)

InfoEase Ltd

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