Quartz: A QoS Architecture for Open Systems
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Abstract:
The term `QoS architecture? is used to describe middleware that provides applications
with mechanisms for specification and enforcement of quality of service (QoS)
requirements. These architectures administer the resources provided by the underlying
system with the intent of fulfilling the QoS requirements imposed by applications.
Substantial work on QoS architectures can be found in the literature. However, the
architectures proposed so far consider only part of the overall problem of delivering
QoS in open systems.
The QoS architectures currently available are able to provide applications in a particular
application area with the guarantees supported by the specific network architecture and
the operating system to which they are bound. Most of these architectures, moreover,
require QoS to be specified by using a low-level format that is not appropriate for
applications that have a more high-level notion of QoS. Due also to their close
integration with the underlying system, these architectures cannot be deployed over
multiple computing platforms. Since they target a specific area of application, the area
in which these architectures can be used is limited. In most cases the underlying system
is not made completely transparent for the application, which still has to deal with lowlevel
issues. In addition, most QoS architectures ignore dynamic resource adaptation,
which can occur due to factors such as resource failure or system reconfiguration.
This thesis describes the design and implementation of Quartz, a QoS architecture for
QoS specification and enforcement in open systems, designed with the aim of solving
the limitations of previous proposals in this area. Quartz is able to handle the differences
between the multiple platforms that may be present in open systems due to its flexible
and extensible structure based on replaceable components. Quartz can also adapt itself
by rearranging its internal components, in order to provide mechanisms for QoS
specification and enforcement suitable for different areas of application. These
requirements are interpreted by Quartz and used to enforce QoS by employing the
resource reservation mechanisms provided by the network and operating system. By
adopting this strategy, Quartz makes the underlying resource reservation mechanisms
transparent to applications requiring QoS enforcement. Furthermore, Quartz provides
support for QoS adaptation by tracking resource adaptations that occur at lower levels
and initiating QoS adaptation whenever needed.
This thesis presents a prototype implementation of the Quartz architecture and a series
of applications built on top of it, including a complete framework for the development
of multimedia applications based on the CORBA architecture. The experience gained by
writing these applications shows the usefulness and efficiency of Quartz as a tool for
supporting QoS specification and enforcement for diverse areas of application in open,
heterogeneous environments.
Author: Siqueira, Frank
Advisor:
Cahill, VinnyQualification name:
Doctor of Philosophy (Ph.D.)Collections:
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