Cloudware Technologies - Guide to Cloud Computing for Business and Technology Managers - page 323

customizable, and isolated execution environment for running applications
without affecting other users' applications. One of the primary reasons
companies implement virtualization is to improve the performance and
efficiency of processing of a diverse mix of workloads. Rather than assign-
ing a dedicated set of physical resources to each set of tasks, a pooled set of
virtual resources can be quickly allocated as needed across all workloads.
Virtualization provides a great opportunity to build elastically scalable sys-
tems that can provision additional capability with minimum costs. SOA is an
architectural style, inspired by the service-oriented approach to computing,
for enabling extensible interoperability. Much of SOA's power and flexibility
derives from its ability to leverage standards-based functional services, call-
ing them when needed on an individual basis, or aggregating them to create
composite applications or multistage business processes. Although the con-
cept of SOA is often discussed in conjunction with Web Services, these two
are not synonymous. Web Services standards are key to enabling interopera-
bility as well as key issues including quality of service (QoS), system seman-
tics, security, management, and reliable messaging.