Cloudware Economics - Guide to Cloud Computing for Business and Technology Managers - page 296

2. Accessibility : Accessibility represents the degree with which a cloud
service request is served. It may be expressed as a probability mea-
sure denoting the success rate or chance of a successful service
instantiation at a point in time. A high degree of accessibility means
that a service is available for a large number of clients and that cli-
ents can use the service relatively easily.
3. Conformance to standards : This describes the compliance of a cloud
service with standards. Strict adherence to correct versions of stan-
dards by service providers is necessary for proper invocation of
cloud services by service requestors. In addition, service providers
must stick to the standards outlined in service-level agreements
(SLAs) between service requestors and providers.
4. Integrity : This describes the degree with which a cloud service per-
forms its tasks according to its Web Service's WSDL description as
well as conformance with Service-Level Agreement (SLA). A higher
degree of integrity means that the functionality of a service is closer
to its Web Service's WSDL description or SLA.
5. Performance : Performance is measured in terms of two factors—
throughput and latency. Throughput represents the number of
cloud service requests served at a given time period. Latency rep-
resents the length of time between sending a request and receiving
the response. Higher throughput and lower latency values represent
good performance of a cloud service. When measuring the transac-
tion/request volumes handled by a cloud service, it is important to
consider whether these come in a steady flow or burst around par-
ticular events like the open or close of the business day or seasonal
rushes.
6. Reliability : Reliability represents the ability of a service to function
correctly and consistently and provides the same service quality
despite system or network failures. The reliability of a cloud service
is usually expressed in terms of the number of transactional failures
per month or year.
7. Scalability : Scalability refers to the ability to consistently serve the
requests despite variations in the volume of requests. High acces-
sibility of cloud services can be achieved by building highly scalable
systems.
8. Security : Security involves aspects such as authentication, authori-
zation, message integrity, and confidentiality. Security has added
importance because cloud service invocation occurs over the
Internet. The amount of security that a particular cloud service
requires is described in its accompanying SLA, and service provid-
ers must maintain this level of security.