Cloud Computing 101
In the discussion of cloud computing it is important is to acknowledge that there is not one type of cloud, but rather several types. The National Institute of Standards and Technology (NIST) has succinctly defined cloud computing with five essential characteristics, three service models, and four deployment models.
5 essential characteristics of cloud computing:
- Broad network access: Capabilities are accessed over the network using standard mechanisms (e.g., web browsers).
- Rapid elasticity: Capabilities can quickly scale out and are rapidly released to scale in, based on provisioning. To the consumer, availability often appears to be unlimited and can be purchased in any quantity at any time.
- On-demand self service: Unilaterally provisioned computing capabilities are provided on an as-needed basis without human intervention.
- Measured service: Resource use is optimized by leveraging a metering capability. Usage can be monitored, controlled, and reported, providing transparency into the use of the service.
- Resource pooling: Computing resources are pooled to serve multiple consumers using a multitenant model with different virtual and physical resources that are dynamically assigned and reassigned based on consumer demand.
3 service models of cloud computing:
- Software as a Service (SaaS): Applications running in a provider’s infrastructure. Examples include Salesforce.com and Google Apps.
- Platform as a Service (PaaS): Application development platform running in provider’s infrastructure. Examples include Force.com, Windows Azure, Google App Engine.
- Infrastructure as a Service (IaaS): Fundamental computing resources provided to the consumer, who can then develop on them using arbitrary software (including operating systems and applications). Examples include Amazon Elastic Compute Cloud (EC2).
4 deployment options for cloud computing:
- Private cloud: Infrastructure is operated solely for an organization.
- Community cloud: Infrastructure is shared by several organizations and supports a specific community that has shared concerns.
- Public cloud: Made available to the general public or a large industry group and owned by a third-party provider.
- Hybrid cloud: A composition of two or more clouds (community, private, or public) that are bound together by standardization or proprietary technology for data and applications portability.
The NIST cloud computing definition can be found at csrc.nist.gov/groups/SNS/cloud-computing/cloud-def-v15.doc.