Here is what the book Cloud Computing for Dummies says: “Cloud computing is the next stage in evolution of the Internet. The cloud in cloud computing provides the means through which everything — from computing power to computing infrastructure, applications, business processes to personal collaboration — can be delivered to you as a service wherever and whenever you need.” The cloud can be public, private or hybrid (both public and private). Many companies feel that the cloud, for them, a is more cost-effective way to deliver IT services internally to their own staff and publicly. For example, companies may decide that testing, software development, storage, and email are good candidates for cloud computing.
Cloud Computing for Dummies defines the cloud this way: “The cloud itself is a set of hardware, networks, storage, services, and interfaces that enable the delivery of computing as a service. Cloud services include the delivery of software, infrastructure, and storage over the Internet (either as separate components or a complete platform) based on user demand.”
When you are first learning about the cloud, you may find it difficult to navigate through all of the different options and combinations of technologies available. Be patient. Persevere. It will be worth it. The difficulty is understanding the different application programming interfaces (APIs), the third characteristic listed below.
Overall, the cloud embodies the following four basic characteristics:
- Elasticity and the ability to scale up and down
- Self-service provisioning and automatic deprovisioning
- Application programming interfaces (APIs)
- Billing and metering of service usage in a pay-as-you-go model
Wikipedia says: “In cloud computing, elasticity is defined as ‘the degree to which a system is able to adapt to workload changes by provisioning and de-provisioning resources in an autonomic manner, such that at each point in time the available resources match the current demand as closely as possible'”.
Application Programming Interfaces
Cloud Computing for Dummies says: “Cloud services need to have standardized APIs. These interfaces provide the instructions on how two application or data sources can communicate with each other. A standardized interface lets the customer more easily link a cloud service, such as a customer relationship management system with a financial accounts management system, without having to resort to custom programming.”