Cloud Service Models

There are the following three types of cloud service models:

Model	Description
Infrastructure as a Service (IaaS)	A provider offers customers access to storage, network components, servers and other IT resources in the cloud, which are billed on the basis of usage.
Platform as a Service (PaaS)	A service provider gives users access to a cloud-based environment in which they can develop and deploy applications. The provider provides the underlying infrastructure.
Software as a Service (SaaS)	A service provider provides software and applications over the Internet. The users “subscribe” to the software and access it via the web or via the provider's APIs.

Compare it to the real-life (abstract explanation):

Infrastructure as a Service (IaaS)

When modernizing SAP landscapes, the question of the operating model automatically arises. Anyone who is responsible for operation must, among other things, take care of cost-effectiveness and smooth operating processes, including automation, if necessary.

There are three decisive advantages in using IaaS with SAP:

Advantage	Description
Time to value	You can use infrastructure quickly and in line with your needs when you need it — without lengthy procurement processes, without construction and without setup work.
Kostenoptimierung	You can scale infrastructure very easily and only pay for what you actually need. There is no need for one-time infrastructure investments.
Sicherheit	Securing the infrastructure is an important but difficult task. Here, professional IaaS providers can often offer higher and standardized security levels than internal departments could.

Software as a Service (SaaS)

Software-as-a-service models have been becoming increasingly popular since 2010 and are increasingly replacing classic on-premise models. Many providers advertise them as an inexpensive, simple and, above all, quick way of making products available.

Definition

Software as a service (SaaS) is software that is owned, delivered and managed remotely by one or more providers. The provider delivers software based on one set of common code and data definitions that is consumed in a one-to-many model by all contracted customers at anytime on a pay-for-use basis or as a subscription based on use metrics.

Gartner

What is Software-as-a-service?

In addition to infrastructure-as-a-service and platform-as-a-service, SaaS is one of the main categories of cloud computing. Since the deployment models have some subtleties, the comparison is based on the official Gartner definition.

Model	Hosting	Description	Example
On-Premise	No Hosting	The software is operated in the customer's infrastructure.	SAP S/4HANA SAP Cloud Connector
Managed Service / PaaS	Private Cloud	The software is operated in the company's data center.	SAP Cloud Connector
Managed Service / PaaS	Public Cloud	The software is operated in the company's data center.	SAP Cloud Platform ABAP Environment
Managed Service / SaaS	Multi-Tenant	The software is operated, managed and maintained by the provider with other customers in a common environment.	SAP Customer Experience
Managed Service / SaaS	Single-Tenant	The software is operated, managed and maintained by the provider with other customers in a single environment.	UDINA Service Excellence