The cloud computing applications handbook

the long version

Cloud application services or "Software as a Service (SaaS)" deliver software as a service over the Internet, eliminating the need to install and run the application on the customer's own computers and simplifying maintenance and support. People tend to use the terms "SaaS" and "cloud" interchangeably, when in fact they are two different things. Key characteristics include: - Network-based access to, and management of, commercially available (i.e., not custom) software. - Activities that are managed from central locations rather than at each customer's site, enabling customers to access applications remotely via the Web . - Application delivery that typically is closer to a one-to-many model (single instance, multi-tenant architecture) than to a one-to-one model, including architecture, pricing, partnering, and management characteristics. -Centralized feature updating, which obviates the need for downloadable patches and upgrades.