IaaS vs. PaaS vs. SaaS - What's the Dif­fer­ence?

Cloud computing service models offer de­velopers many ad­vant­ages in everyday life: Depending on the preferred model, de­velopers can work with clearly defined areas of ap­plic­a­tion, helping them map web de­vel­op­ments in a scalable and, at the same time, cost-accurate manner with a pay-per-use model. In addition to specific services such as Backend as a Service and Function as a Service, you’ll find In­fra­struc­ture, Platform, and Software as a Service (IaaS, PaaS, SaaS). These com­pre­hens­ive solutions let self-employed in­di­vidu­als, agencies, and companies of different sizes focus on cloud computing in a tailored way.

In this article, we introduce the different cloud computing service models and explain the dif­fer­ences between Software as a Service, Platform as a Service, and In­fra­struc­ture as a Service.

In the field of cloud computing services, a number of models have es­tab­lished them­selves for the de­vel­op­ment of web ap­plic­a­tions. These so-called XaaS models share a number of common features, such as location-in­de­pend­ent usage options, so that de­vel­op­ment teams from different countries can fall back on an existing structure. As the name suggests, the services are hosted in the cloud by the re­spect­ive provider, making main­ten­ance and update routines a thing of the past. With IaaS, PaaS, and SaaS, users receive different XaaS services, which involve little to very little ad­min­is­trat­ive effort.

Probably the best-known and most fre­quently used cloud computing service is Software as a Service (SaaS). This model provides users and de­velopers with the greatest scope, while also providing the greatest overall as­sist­ance. The service usually refers to centrally provided web ap­plic­a­tions with a wide range of functions and areas of ap­plic­a­tion. The ap­plic­a­tions don’t run on their own computer, but via a cloud. Examples of SaaS ap­plic­a­tions can be found in content man­age­ment systems (CMS), in customer re­la­tion­ship man­age­ment (CRM), or in eCommerce.

SaaS ap­plic­a­tions often replace several programs at once, so users only need one license, which greatly minimises ad­min­is­trat­ive efforts and saves costs. Another advantage is that, despite the extensive functions, SaaS ap­plic­a­tions don’t require any main­ten­ance or resources to operate. Regular updates, for example security patches, are auto­mat­ic­ally dis­trib­uted by the providers.

Platform as a Service (PaaS) refers to a cloud computing service that provides de­velopers with a de­vel­op­ment en­vir­on­ment and the tools they need to develop new ap­plic­a­tions. This service is par­tic­u­larly suitable when web ap­plic­a­tions need to be deployed quickly and easily. The advantage is that de­velopers don’t have to worry about con­fig­ur­ing and main­tain­ing the necessary in­fra­struc­ture.

The platform gives de­velopers access to pre-pro­grammed ap­plic­a­tion com­pon­ents, so that they can quickly develop cloud-based apps, for example. Testing of the developed ap­plic­a­tions is also possible via PaaS when the provider makes the necessary resources available via the cloud.

In­fra­struc­ture as a Service (IaaS) is the smallest of the three cloud computing service models in terms of scope. With this model, users receive an IT in­fra­struc­ture that is provided via the Internet. The data centres required for this are operated and managed by the cloud provider. Storage and ad­min­is­tra­tion are the re­spons­ib­il­ity of the provider, from whom users book the required computing power and the scope of the network struc­tures according to their in­di­vidu­al needs.

Other common cloud service models are Backend as a Service (BaaS) and Function as a Service (FaaS), which are more spe­cial­ised than SaaS, PaaS, and IaaS in their scope and areas of ap­plic­a­tion. What all cloud computing services have in common is that they can be scaled up and down. With the as­so­ci­ated pay-as-you-use payment models, costs are only incurred for what users and de­velopers actually use. This makes XaaS models genuine al­tern­at­ives to con­ven­tion­al struc­tures.