Software As A Service
A software delivery method that provides access to software and its functions remotely as a Web-based service. Software as a Service allows organizations to access business functionality at a cost typically less than paying for licensed applications since SaaS pricing is based on a monthly fee. Also, because the software is hosted remotely, users don't need to invest in additional hardware. Software as a Service removes the need for organizations to handle the installation, set-up and often daily upkeep and maintenance.
Software as a Service may also be referred to as simply hosted applications. For example: NIDS OwnCloud acting as hard drives in the sky that help you do all kinds of things—such as creating a bulletproof (almost) backup system or turbo charging your productivity to blistering new levels—no matter where you are.
Platform As A Service
Platform as a Service (PaaS) brings the benefits that SaaS bought for applications, but over to the software development world. PaaS can be defined as a computing platform that allows the creation of web applications quickly and easily and without the complexity of buying and maintaining the software and infrastructure underneath it. PaaS is analogous to SaaS except that, rather than being software delivered over the web, it is a platform for the creation of software, delivered over the web.
PaaS is especially useful in any situation where multiple developers will be working on a development project or where other external parties need to interact with the development process. As the case study below illustrates, it is proving invaluable for those who have an existing data source – for example sales information from a customer relationship management tool, and want to create applications which leverage that data. Finally PaaS is useful where developers wish to automate testing and deployment services.
The popularity of agile software development, a group of software development methodologies based on iterative and incremental development, will also increase the uptake of PaaS as it eases the difficulties around rapid development and iteration of software.
Infrastructure As A Service
A way of delivering Cloud Computing infrastructure – servers, storage, network and operating systems – as an on-demand service.
Rather than purchasing servers, software, datacenter space or network equipment, clients instead buy those resources as a fully outsourced service on demand. As with the two previous sections, SaaS and PaaS, IaaS is a rapidly developing field. That said there are some core characteristics which describe what IaaS is.
IaaS is generally accepted to comply with the following:
» Resources are distributed as a service
» Allows for dynamic scaling
» Has a variable cost, utility pricing model
» Generally includes multiple users on a single piece of hardware
