InformationWeek SMB TechEncyclopedia

(1) See grid computing.

(2) Using the Web server facilities of a third party provider on the Internet (the "cloud") to store, deploy and run applications. Cloud computing takes two forms. It may refer to "utility" computing in which only the hardware and software infrastructure (operating system, databases, etc.) are offered, or it may refer to "software as a service" (SaaS), which includes the business applications as well. Regardless whether the cloud is infrastructure only or includes applications, major features are self service, scalability and speed.

#1 - Do It Yourself
Users do everything online. They sign on to the service and run their applications as desired. Although a person may initially be involved in setting up the service contract, users make all subsequent changes from their computers, typically from their Web browsers.

#2 - Scalability and Speed
The cloud provides virtually unlimited computing capacity and supports extra workloads on demand. In addition, cloud providers may be connected to multiple Tier 1 Internet backbones for fastest response times and availability.

Infrastructure and Applications
More often than not, cloud computing refers to application service providers (ASPs), who offer the whole ball of wax: the infrastructure as outlined below and the applications as well, relieving the organization of virtually all maintenance. There are two kinds: entirely free to the user such as Google Apps, and paid applications such as Salesforce.com.

     This "software-as-a-service" model (SaaS) is a paradigm shift because applications and company data are stored externally. Even if data are duplicated inhouse, copies "in the cloud" create security and privacy issues.

     In all its forms, cloud computing is considered the next great wave in IT and is currently the major buzzword.

Infrastructure Only
Using the cloud for computing power only can be more economical than building new datacenters or expanding existing ones to support new projects or seasonal increases. When constructing a datacenter, there are enormous security, environmental and management issues, not to mention hardware/software maintenance forever after. In addition, cloud facilities may be able to withstand natural disasters that meet and exceed military standards, whereas company datacenters are not generally built to these specfications.

     Infrastructure-only cloud computing is also called "cloud hosting," "utility computing," "grid hosting" and "grid computing."

     For small Web developers and publishers, cloud providers such as Amazon and Google are invaluable (see EC2 and Google App Engine). Because cloud hardware "dynamically scales" (expands capacity on demand), a sudden increase in requests cannot overload a Web server, such as immediately after launching a new product. Configuring sufficient servers inhouse to withstand bursts of traffic means computers run at lower capacity much of the time. Because cloud datacenters charge for actual usage, there is no wasted expense.

     In addition, cloud datacenters employ automatic backup and recovery systems as well as utilize the latest virtualization techniques (see server virtualization). However, the way the cloud provides automatic processes differs. In some cases, they are entirely automatic. In others, the developer has to learn how to configure the cloud's software tools to make them automatic.

Private and Hybrid Clouds
Enterprises also create private clouds within their own datacenters. Employing the same server virtualization techniques as the Internet clouds, the private cloud enjoys the same flexibility and self-service capabilities as the public cloud, but with greater control and privacy.

     A hybrid cloud is using both private and public clouds. When new applications arise, or if the enterprise cloud is overloaded, the public cloud is used. Migrating virtualized applications from internal servers to the Internet and managing both venues from a central console are issues facing network administrators in the 2010s. See SaaS, rich client, EC2, Google App Engine, Windows Azure, thin client, cloud, colocation and Web application.