Cloud computing service models
AWS falls under the category of Cloud computing called Infrastructure as a Service. In Cloud computing there are three service models:
- Infrastructure as a Service (IaaS)
- Platform as a Service (PaaS)
- Software as a Service (SaaS)
Infrastructure as a Service
IaaS can be described as a service that provides virtual abstractions for hardware, servers, and networking components. The service provider owns all the equipment and is responsible for its housing, running, and maintenance. In this case, AWS provides APIs, SDKs, and a UI for creating and modifying virtual machines, their network components, routers, gateways, subnets, load balancers, and much more. Where a user with a physical data center would incur charges for the hardware, shelving, and access, this is removed by IaaS with a payment model that is per-hour (or per-use) type.
Platform as a Service
While AWS itself is an IaaS provider, it contains a product named ElasticBeanstalk, which falls under the PaaS category for Cloud models. PaaS is described as the delivery of a computing platform, typically an operating system, programming language execution environment, database, or web server. With ElasticBeanStalk, a user can easily turn a code into a running environment without having to worry about any of the pieces underneath such as setting up and maintaining the database, web server, or code runtime versions. It also allows it to be scaled without having to do anything other than define scale policies through the configuration.
Software as a Service
AWS also provides a marketplace where a user can purchase official and third-party operating system images that provide configurable services such as databases, web applications, and more. This type of service falls under the SaaS model. The best interpretation for the SaaS model is on-demand software, meaning that the user need only configure the software to use and interact with it. The draw to SaaS is that there is no need to learn how to configure and deploy the software to get it working in a larger stack and generally the charges are per usage-hour.
The AWS suite is both impressive and unique in that it doesn't fall under any one of the Cloud service models as described previously. Until AWS made its name, the need to virtualize an entire environment or stack was usually not an easy task and consisted of a collection of different providers, each solving a specific part of the deployment puzzle. The cost of using many different providers to create a virtual stack might not be cheaper than the initial hardware cost for moving equipment into a data center. Besides the cost of the providers themselves, having multiple providers also created the problem of scaling in one area and notifying another of the changes. While making applications more resilient and scalable, this Frankenstein method usually did not simplify the problem as a whole.
