Basically, there are three types of clouds in cloud computing, they are public, private, and hybrid clouds.

In a public cloud, third-party service providers make resources and services available to their customers via the internet. The customers' applications and data are deployed on infrastructure owned and secured by the service provider.

A private cloud provides many of the same benefits of a public cloud but the services and data are managed by the organization or a third-party, solely for the customer's organization. Usually, private cloud places increase administrative overheads on the customer but give greater control over the infrastructure and reduce security-related concerns. The infrastructure may be located on or off the organization's premises.

A hybrid cloud is a combination of both a private and a public cloud. The decision on what runs on the private versus the public cloud is usually based on several factors, including business criticality of the application, sensitivity of the data, industry certifications and standards required, regulations, and many more. But in some cases, spikes in demand for resources are also handled in the public cloud.

There are three cloud-based service models, IaaS, PaaS, and SaaS. The main features of each of these are listed here:

From an infrastructure perspective, the customer does not manage or control the underlying cloud infrastructure in all three service models.

The following diagram illustrates who is responsible for managing the various components of a typical user application across IaaS, PaaS, and SaaS cloud service models. The column labeled User Application represents the main components of a user application stack, while the following columns depict the varying levels of management responsibilities in each of the three service models. The shaded boxes are managed by the service provider, while the unshaded boxes are managed by the user.

The level of control over operating systems, storage, applications, and certain network components (for example, load balancers) is the highest in the IaaS model, while the least (or none) in the SaaS model.

We would like to conclude our introduction to cloud computing by getting you started on AWS, right away. The next two sections will help you set up your AWS account and familiarize you with the AWS management console.

You will need to create an account on Amazon before you can use the Amazon Web Services (AWS). Amazon provides a 12 month limited fully functional free account that can be used to learn the different components of AWS. With this account, you get access to services provided by AWS, but there are some limitations based on resources consumed. The list of AWS services is available at http://aws.amazon.com/free.

We are assuming that you do not have a pre-existing AWS account with Amazon (if you do, please feel free to skip this section). Perform the following steps:

The AWS management console is the central location from where you can access all the Amazon services. The management console has links to the following:

In this chapter, we introduced you to a few cloud computing concepts and terminologies. We described the basic features of public, private, and hybrid clouds. We introduced the main cloud delivery models, namely, IaaS, PaaS, and SaaS. Finally, we listed the steps for creating your AWS account, and described the salient features of the AWS management console.

With the basics out of the way, in the next chapter we will deep dive into the details of how multitenanted cloud applications are different from traditional multi-tiered applications. We will also walk you through creating a sample application (using Spring and MySQL) that will be used to illustrate key cloud application design concepts through the rest of this book.