The Hostway Blog

IaaS vs. PaaS vs. SaaS: What's It All Mean?

When talking about the cloud, it’s easy to be overwhelmed by the proliferation of acronyms. Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS) are three you'll likely see the most; according to recent analyst reports, all are growing at a rapid clip as cloud adoption rises. Gartner estimates that of the $131 billion cloud computing market, these three fundamental service models represent more than 20 percent of expenditures: PaaS comes in at about one percent, whereas SaaS sits at 14.7 percent of the market and IaaS at 5.5 percent.

In an IaaS model, businesses outsource the equipment they need to support their operations – including hardware, servers, storage and networking components – to a service provider who delivers and maintains this equipment. Businesses turn to IaaS solutions to avoid the capital expenditure outlay for equipment such as servers, and also because they can scale quickly and easily. If the scale of their operations fluctuates, or if they are looking to expand, they can tap into the cloud resource as needed rather than purchase, install and integrate hardware themselves. Meanwhile, the service provider owns the equipment and is responsible for housing, servicing and upgrading it.

SaaS (also known as hosted applications) is a hosting model in which applications use a set of common code and are owned, delivered and managed remotely by a vendor or service provider, made available to customers over the Internet. SaaS allows organizations to access business software at a monthly or annual fee that is typically less than paying for the applications outright. It does not need to be installed, set up or maintained, as the software is hosted remotely. This means that businesses don't need to invest in additional hardware.

Sitting between the two is PaaS, which draws from both concepts. In a PaaS model, businesses rent virtualized servers and associated services for running existing applications or developing and testing new ones. With PaaS, operating system features can be changed and upgraded frequently, and geographically distributed development teams can work together on software development projects. PaaS helps cut costs because programming development efforts can be unified.

If PaaS sounds a lot like IaaS, there’s a good reason: They share a lot of the same characteristics and, according to some industry pundits, PaaS will likely be consumed by IaaS in the near future as IaaS vendors include PaaS capabilities within their offerings. PaaS is today's most ill-defined area of cloud computing, these industry experts argue, with approaches, features and definitions varying widely among providers. Most PaaS offerings provide only the features and functions that build and deploy applications, lacking access other resources and tools to support specific features, such as remote and native APIs, as well as middleware and database services. Still, other surveys indicate that PaaS is growing at a rate that may sustain its independence as a model of business.

PaaS has played an important role in the cloud thus far, but the market will soon decide if it's meant to stand alone or meld quietly into the IaaS landscape. In the unpredictable realm of information technology, contradictory forecasts are nothing new. We’ll simply have to wait and see where the market goes.