As military, academic, and commercial computing systems evolve from
autonomous entities that deliver computing products into network
centric enterprise systems that deliver computing as a service,
opportunities emerge to consolidate computing resources, software and
information through cloud computing. Along with these opportunities
come challenges, especially to service providers and operations
centers that struggle to monitor and manage Quality of Service (QoS)
for these services in order to meet customer service
commitments. Traditional approaches fall short in addressing these
challenges because they examine QoS from a limited perspective rather
than from a System of Systems (SoS) perspective applicable to a
net-centric enterprise system in which any user from any location can
share computing resources at any time. This paper presents a SoS
approach to enable QoS monitoring, management, and response for
enterprise systems that deliver computing as a service through a cloud
computing environment. A concrete example is provided for application
of this new SoS approach to a real-world scenario ({\emph{viz.}},
Distributed Denial of Service). Simulated results confirm the
efficacy of the approach.