Cloud computing is the latest market-oriented computing paradigm which
brings software design and development into a new era characterized by
"XaaS", i.e. everything as a service. Cloud workflows, as typical
software applications in the cloud, are composed of a set of partially
ordered cloud software services to achieve specific goals. However, due
to the low QoS (quality of service) nature of the cloud environment, the
design of workflow systems in the cloud becomes a challenging issue for
the delivery of high quality cloud workflow applications. To address
such an issue, this book presents a systematic investigation to the
three critical aspects for the design of a cloud workflow system, viz.
system architecture, system functionality and quality of service.
Specifically, the system architecture for a cloud workflow system is
designed based on the general four-layer cloud architecture, viz.
application layer, platform layer, unified resources layer and fabric
layer. The system functionality for a cloud workflow system is designed
based on the general workflow reference model but with significant
extensions to accommodate software services in the cloud. The support of
QoS is critical for the quality of cloud workflow applications. This
book presents a generic framework to facilitate a unified design and
development process for software components that deliver lifecycle
support for different QoS requirements. While the general QoS
requirements for cloud workflow applications can have many dimensions,
this book mainly focuses on three of the most important ones, viz.
performance, reliability and security. In this book, the architecture,
functionality and QoS management of our SwinDeW-C prototype cloud
workflow system are demonstrated in detail as a case study to evaluate
our generic design for cloud workflow systems. To conclude, this book
offers a general overview of cloud workflow systems and provides
comprehensive introductions to the design of the system architecture,
system functionality and QoS management.
