Evaluating cloud service models
In the early days, the cloud was merely another datacenter that hosted a multitude of customers, sharing resources such as compute power, network, and storage. The cloud has evolved over the years, now offering a variety of service models. In this section, you will learn the fundamentals of these models.
IaaS
IaaS is likely still the best-known service model of the cloud. Typically, enterprises still start with IaaS when they initiate the migration to cloud providers. In practice, this means that enterprises perform a lift and shift of their (virtual) machines to resources that are hosted in the cloud. The cloud provider will manage only the infrastructure for the customer: network, storage, compute, and the virtualization layer. The latter is important, since customers will share physical resources in the cloud. These resources—for instance, servers—are virtualized so they can host multiple instances.
PaaS
With PaaS cloud providers take more responsibility over resources, now including operating systems and middleware. A good example is a database platform. Customers don’t need to take care of the database platform, but simply run a database instance on a database platform. The database software, for example, MySQL or PostgreSQL, is taken care of by the cloud provider, including the underlying operating systems.
SaaS
SaaS is generally perceived as the future model for cloud services. It basically means that the cloud provider manages everything in the software stack, from the infrastructure to the actual application with all its components, including data. Software updates, bug fixes, and infrastructure maintenance are all handled by the cloud provider. The user, who typically uses the application through some form of subscription, connects to the app through a portal or API without installing software on local machines.
FaaS
FaaS refers to a cloud service that enables the development and management of serverless computing applications. Serverless does not mean that there are no services involved, but developers can program services without having to worry about setting up and maintaining a server: that’s taken care of by the cloud provider. The big advantage is that the programmed service only uses the exact amount of, for instance, CPU and memory, instead of an entire virtual machine.
CaaS
A growing number of enterprises are adopting container technology to host, run, and scale their applications. To run containers, developers must set up a runtime environment for these containers. Typically, this is done with Kubernetes, which has developed as the industry standard to host, orchestrate, and run containers. Setting up Kubernetes clusters can be complex and time-consuming. Container as a Service (CaaS) is the solution. CaaS provides an easy way to set up container clusters.
XaaS
Anything as a Service (XaaS) is a term used to express the idea that users can have everything as a service. The concept is widely spread with, for instance, Hardware as a Service (HaaS), Desktop as a Service (DaaS), or Database as a Service (DBaaS). This is not limited to IT, though. The general idea is that companies will offer services and products in an as a service model, using the cloud as the digital enabler. Examples are food delivery to homes, ordering taxis, or consulting a doctor using apps.
Although we will touch upon SaaS and containers, we will focus mainly on IaaS and PaaS as starting points to adopt multi-cloud. With that in mind, we can start by setting out our multi-cloud strategy.
