Chapter 11. Introduction to Cloud Computing

This chapter introduces the concepts of Cloud computing, Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). The top Cloud providers are also discussed briefly.

In a nutshell, the following topics will be covered throughout this chapter:

• Cloud computing basics
• Concepts and terminology
• Goals and benefits
• Risks and challenges
• Roles and boundaries
• Cloud characteristics
• Cloud delivery models
• Cloud deployment models

Whether you are running applications that share photos across millions of mobile users or whether you are supporting the critical operations of your business, a Cloud services platform offers rapid access to flexible and low-cost IT resources. With Cloud computing, you don't need to invest heavily on managing hardware. Instead, you can provision the suitable computing resources that you need to power your ideas or manage your IT department's operations. You can instantaneously access the required resources...

Concepts and terminology

This section introduces the fundamental concepts of a Cloud and its artifacts.

Cloud

A Cloud refers to a distinct IT environment that is designed for remote provisioning of scalable and measured IT resources. The term originated as a metaphor for the internet to describe a network of networks providing remote access to a set of decentralized IT resources. Before Cloud computing was a formal IT segment, a Cloud symbol was commonly used to represent the Internet in a variety of specifications and mainstream documentation of web-based architectures.

IT resource

An IT resource is a physical or a virtual IT-related artifact that can be either software-based, such as a virtual server or a custom software program, or hardware-based, such as a physical server or a network device.

On-premise

As a distinct and remotely accessible environment, a Cloud represents an option for the deployment of IT resources. An IT resource hosted in a conventional IT enterprise within an organizational...

Goals and benefits

Similar to wholesalers, public Cloud providers base their business model on mass acquisition of IT resources, which are made available to Cloud consumers for attractive prices. This helps organizations to access powerful infrastructure without any infrastructure costs.

The most common economic rationale for investing in Cloud-based IT resources is to reduce initial IT investments, such as hardware, software purchases, and ownership costs. A cloud's measured usage characteristic represents a feature set that allows measured operational expenditures (directly related to business performance) to replace anticipated capital expenditures. This is also referred to as proportional cost.

The reduction of costs allow enterprises to start small, to increase IT resource allocation as needed. Moreover, lower initial expenses allow for capital to be redirected to core business investments. Opportunities to decrease costs are derived from the deployment and operation of large-scale data...

Risks and challenges

Several of the most critical Cloud computing challenges, pertaining mostly to Cloud consumers that use IT resources located in public Clouds, are presented and examined.

Increased security vulnerabilities

Migration of business data to the Cloud means that the responsibility of data security becomes shared with the Cloud provider. Remote usage of IT resources requires an expansion of trust boundaries by the Cloud consumer to include the external Cloud. It can be difficult to properly address multi-regional compliance and legal issues due to the fact that third-party Cloud providers will frequently establish data centers in affordable or convenient geographical locations. Cloud consumers will often not be aware of the physical location of their IT resources and data when hosted by public Clouds. For some organizations, this can pose serious legal concerns pertaining to industry or government regulations that specify data privacy and storage policies.

The presence of the multiple...

Roles and boundaries

Organizations and humans can assume different types of predefined roles depending on how they relate to and/or interact with a Cloud and its hosted IT resources. Each of the upcoming roles participates in and carries out responsibilities in relation to Cloud-based activity. The following sections define these roles and identify their main interactions.

Cloud provider

The organization that provides Cloud-based IT resources is the Cloud provider. When assuming the role of Cloud provider, an organization is responsible for making Cloud services available to Cloud consumers as per the agreed SLA terms. The Cloud provider is further tasked with any required management and administrative duties to ensure smooth ongoing operation of the overall Cloud infrastructure.

Cloud providers normally own IT resources that are made available for lease by Cloud consumers; however, some Cloud providers also resell IT resources leased from other Cloud providers.

Cloud consumer

A Cloud consumer...

Cloud characteristics

An IT environment requires a specific set of characteristics to enable the remote provisioning of scalable and measured IT resources in an effective manner. These characteristics need to exist to a meaningful extent for the IT environment to be considered an effective Cloud.

The following six specific characteristics are common to the majority of Cloud environments:

• On-demand usage
• Ubiquitous access
• Multitenancy (and resource pooling)
• Elasticity
• Measured usage
• Resiliency

On-demand usage

A Cloud consumer can unilaterally access Cloud-based IT resources, giving the Cloud consumer the freedom to self-provision these IT resources. Once configured, usage of the self-provisioned IT resources can be automated, reducing human involvement with the Cloud consumer or Cloud provider. This results in an on-demand usage environment. Also known as on-demand self-service usage, this characteristic enables the service-based and usage-driven features found in mainstream Clouds.

Ubiquitous access...

Cloud delivery models

A Cloud delivery model represents a specific, pre-packaged combination of IT resources offered by a Cloud provider. Three common Cloud delivery models have become widely established and formalized:

• IaaS
• PaaS
• SaaS

Infrastructure as a Service

The IaaS delivery model represents a self-contained IT environment that comprises infrastructure-centric IT resources that can be accessed and managed using Cloud service-based interfaces and tools. This environment can include hardware, network, connectivity, operating systems, and other raw IT resources. In contrast to traditional hosting or outsourcing environments, with IaaS, IT resources are usually virtualized and packaged into bundles that simplify runtime scaling and customization of the infrastructure.

The general purpose of an IaaS environment is to provide Cloud consumers with a high level of control and responsibility over its configuration and utilization. The IT resources provided by IaaS are generally not preconfigured,...

Cloud deployment models

A Cloud deployment model represents a specific type of Cloud environment, primarily distinguished by ownership, size, and access.

The following sections describe the four common Cloud deployment models:

• Public Cloud
• Community Cloud
• Private Cloud
• Hybrid Cloud

Public Clouds

A public Cloud is a publicly accessible Cloud environment owned by a third-party Cloud provider. The IT resources on public Clouds are usually provisioned using the previously described Cloud delivery models and are generally offered to Cloud consumers at a cost or are commercialized using other avenues (such as advertisements).

The Cloud provider is responsible for the creation and ongoing maintenance of the public Cloud and its IT resources. Many of the scenarios and architectures explored in upcoming chapters involve public Clouds and the relationship between the providers and consumers of IT resources using public Clouds.

Community Clouds

A community Cloud is similar to a public Cloud except that its access...

Summary

In this chapter, we discussed Cloud computing and the key terminology used to understand and implement Cloud computing. 

In the next chapter, we will explore one of the most popular Cloud providers from Amazon: AWS.