Page 18 - Cloud computing: From paradigm to operation

1 Framework and requirements for cloud computing

6 Cloud computing overview

6.1 General

Cloud computing is a paradigm for enabling network access to a scalable and elastic pool of shareable
physical or virtual resources with self-service provisioning and administration on-demand. The cloud
computing paradigm is composed of key characteristics, cloud computing roles and activities, cloud
capabilities types and cloud service categories, cloud deployment models and cloud computing cross
cutting aspects that are briefly described in this clause 6.

6.2 Key characteristics
Cloud computing is an evolving paradigm. This clause 6.2 identifies and describes key characteristics of cloud
computing and is not intended to prescribe or constrain any particular method of deployment, service
delivery, or business operation.
Key characteristics of cloud computing are:
– Broad network access: A feature where the physical and virtual resources are available over a
network and accessed through standard mechanisms that promote use by heterogeneous client
platforms. The focus of this key characteristic is that cloud computing offers an increased level of
convenience in that users can access physical and virtual resources from wherever they need to
work, as long as it is network accessible, using a wide variety of clients including devices such as
mobile phones, tablets, laptops, and workstations;
– Measured service: A feature where the metered delivery of cloud services is such that usage can be
monitored, controlled, reported, and billed. This is an important feature needed to optimize and
validate the delivered cloud service. The focus of this key characteristic is that the customer may
only pay for the resources that they use. From the customers' perspective, cloud computing offers
the users value by enabling a switch from a low efficiency and asset utilization business model to a
high efficiency one;
– Multi-tenancy: A feature where physical or virtual resources are allocated in such a way that
multiple tenants and their computations and data are isolated from and inaccessible to one another.
Typically, and within the context of multi-tenancy, the group of cloud service users that form a
tenant will all belong to the same cloud service customer organization. There might be cases where
the group of cloud service users involves users from multiple different cloud service customers,
particularly in the case of public cloud and community cloud deployments. However, a given cloud
service customer organization might have many different tenancies with a single cloud service
provider representing different groups within the organization;
– On-demand self-service: A feature where a cloud service customer can provision computing
capabilities, as needed, automatically or with minimal interaction with the cloud service provider.
The focus of this key characteristic is that cloud computing offers users a relative reduction in costs,
time, and effort needed to take an action, since it grants the user the ability to do what they need,
when they need it, without requiring additional human user interactions or overhead;
– Rapid elasticity and scalability: A feature where physical or virtual resources can be rapidly and
elastically adjusted, in some cases automatically, to quickly increase or decrease resources. For the
cloud service customer, the physical or virtual resources available for provisioning often appear to
be unlimited and can be purchased in any quantity at any time automatically, subject to constraints
of service agreements. Therefore, the focus of this key characteristic is that cloud computing means
that the customers no longer need to worry about limited resources and might not need to worry
about capacity planning;

– Resource pooling: A feature where a cloud service provider's physical or virtual resources can be
aggregated in order to serve one or more cloud service customers. The focus of this key
characteristic is that cloud service providers can support multi-tenancy while at the same time using
abstraction to mask the complexity of the process from the customer. From the customer's
perspective, all they know is that the service works, while they generally have no control or

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