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These materials are the copyright of John Wiley & Sons, Inc. and any dissemination, distribution, or unauthorized use is strictly prohibited. 6 Platform as a Service For Dummies, Special Edition traditionally siloed computing assets into a shared pool of resources that are based on an underlying Internet foundation. Cloud computing makes these resources easier to use by supporting a self-service model so resources can be acquired or provisioned based on need or assigned business rules. At the same time, a business can use just the resources it needs to complete a task. After that task is completed, those resources can be returned to the pool. How does this work Some foundational capabilities are required to support this computing model, including the following characteristics: ✓ Self-service provisioning and automatic de-provisioning: Provisioning technology provides an automated way for users to add and subtract services based on need and business requirements. ✓ Elasticity and the ability to scale up and down: With elasticity, the user is able to acquire more resources in an on demand manner, for a small duration and pays for the capacity or capability they need. When those resources are no longer needed, the user is able to return that capacity. ✓ Resource pooling: Cloud architectures enable the efficient creation of groups of shared resources that make the cloud economically viable. ✓ Billing and metering of service usage: Because customers pay only for the resources they purchase or acquire, cloud computing environments include a way to monitor and measure usage. Equally important is that the cloud provides a new economic model of computing. Instead of purchasing, managing, and maintaining a software and server environment, a business is able to purchase computing on a situational basis, avoiding capital expenditures. If a company has already invested in an internal computing environment that best serves business requirements, portions of that environment can be transformed into what’s called a private cloud environment with the same self-service and service management characteristics as what’s called a public cloud service. While in both cases the cloud provides elasticity that allows the pool of resources to expand or contract based on need, some key differences still remain:
These materials are the copyright of John Wiley & Sons, Inc. and any dissemination, distribution, or unauthorized use is strictly prohibited. Chapter 1: Setting the Fundamentals of the Cloud 7 ✓ A public cloud makes an unlimited pool of resources, such as applications and storage, available to the general public over the Internet. Public cloud services may be free or offered on a pay-per-usage model. ✓ A private cloud is more constrained to the size of the internal computing environment constructed by the company and may have to be set up, managed, and administered by the company itself. Access to a private cloud is restricted to those users who are granted permission. One important factor with these services is that the IT organization offloads the responsibility for maintaining the application or service. The public cloud provider takes over that responsibility. In addition, the organization can add services when they’re needed. This approach saves time, money, and effort. Defining Cloud Computing Models Your understanding of the benefits of cloud computing must begin with an understanding of the foundational services. The term service is defined as a task that has been packaged so it can be automated and delivered to customers in a consistent and repeatable manner. Any cloud service has a set of consistent characteristics: a customer can go to the self-service interface and add more compute, middleware, or database services or another application. When that service is no longer needed, its use is discontinued and no further charge is assessed. Three fundamental layers of cloud services exist: IaaS, SaaS, and PaaS. Getting straight with IaaS Infrastructure as a Service (IaaS) is one of the most straightforward services of the cloud computing services. IaaS is the delivery of compute services including servers, networking, and storage, based on a rental model. IaaS has to be either a public or a private service. This differs from traditional hosting models because a service can be acquired for a set time period. In other words, the consumer of the service is charged only for that usage instead of having to sign a long-term contract.
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