Exploring cloud computing models

Cloud computing today offers businesses the ability to offload the cost and complexity of hosting and managing their applications—for example, many providers offer mainstream applications as a complete service that does not require any kind of infrastructure management by the customer. Examples include Microsoft Office 365, which is a suite of desktop productivity applications including email, messaging, and collaboration services offered via the internet. At the same time, many organizations also need to host bespoke line-of-business (LOB) applications such as those developed in-house. Often, this means that they need access to configure the necessary infrastructure in a manner best suited to the needs of the application.

To that end, companies can enlist the services of cloud providers such as AWS, which offers different cloud models to suit the specific needs of the business. The following are three main cloud models offered by most cloud vendors such as AWS.

Infrastructure as a Service

The Infrastructure as a Service (IaaS) model offers the greatest flexibility in giving the customer access and the ability to configure the underlying network, storage, and compute services that power their LOB applications. This model is very similar to owning and managing your own physical infrastructure. However, with cloud computing, a clear difference lies in the fact that you work with virtualized infrastructure components rather than having access to the underlying physical components.

The IaaS cloud computing model is ideal if you need greater control over how your infrastructure components need to be configured (usually from the operating system layer up) to support a given application.

Platform as a Service

Platform as a Service (PaaS) is another cloud computing model designed to remove the burden of configuring and managing underlying infrastructure resources such as compute, storage, and network services. PaaS is designed to allow your organization to focus on developing your application code and offers you a platform to deploy and manage your application releases, updates, and upgrades.

As your developers deploy their application code on the PaaS environment, the provider provisions the infrastructure required to support the application. This will include the necessary network architecture, firewall rules, storage, compute services, operating system management, and runtime environments.

Depending on your vendor, the PaaS model may still offer some degree of flexibility in how the underlying infrastructure is configured. AWS, for example, gives you the option to make necessary modifications to the underlying infrastructure, offering an additional level of flexibility. Example of such services include AWS Elastic Beanstalk, AWS OpsWorks, AWS Lambda, and Amazon Relational Database Service (RDS). While the PaaS model offered by AWS removes the need to minutely configure every infrastructure component (something you would have to do with an IaaS model), it still offers the flexibility of deciding just which components are deployed to support your application.

SaaS

With a SaaS model, the applications are completely hosted and managed by the provider. SaaS services take away any need to set up physical infrastructure to host an application. Instead, you simply connect to those applications via the internet and consume the services offered. A majority of SaaS applications today are fully functional via a standard web browser. This also means that there is no requirement to install any client software.

While the need to set up and configure any infrastructure to host a SaaS application is solely owned and managed by the vendor, many SaaS-based applications still require some form of configuration to meet the specific requirements of your business. You will still need to either have in-house expertise to configure the application to your specification or get support from the provider/third parties. For example, Microsoft Office 365 is a SaaS-based online suite of productivity applications that combines email, file-share, and collaboration services. Although you do not need any physical hardware on premises to host the application since it is accessible as a complete product over the internet, you will have to configure the software elements to meet your business needs. This includes security configurations, configuring your domain name to be associated with the email services offered, or enabling encryption services.

Let's look at some typical examples of IaaS, PaaS, and SaaS models, as follows:

Table 1.1 – Cloud computing models

In this section, we explored cloud computing models. We gained an understanding of the key differences between core models such as IaaS, PaaS, and SaaS. Each model comes with its own set of management overheads and with it, the flexibility to design, build, and deploy your applications.

In the next section, we examine cloud deployment models. Here, we assess the differences between hosting your own on-premises cloud (or private cloud) and using the services of a public cloud provider. We also look at how to connect your private cloud environment with the resources you might host with a public cloud provider.