Cactus
CACTUS
An Integrated Framework for Dynamic Fine-Grain QoS
Richard D. Schlichting, Principal Investigator
Matti A. Hiltunen, Co-Principal Investigator
Department of Computer Science
The University of Arizona
The goal of this project, titled Cactus , is to develop a design and
implementation framework for supporting customizable dynamic fine-grain
Quality of Service (QoS) attributes related to dependability, real time, and
security in
distributed systems. This framework is based on a multi-level integrated
approach, with middleware services between the application and operating
system implementing the relevant attributes. These services are divided
into a task support (TS) layer that provides QoS guarantees related
to task execution, and an underlying distribution support (DS) layer
that provides QoS guarantees related to network communication. The layers
are translucent in the sense that each provides a standard data interface
plus a systemic interface for QoS management. They are integrated in the
sense that the two layers cooperate to provide QoS guarantees for a given
application.
Customization and the ability to adapt dynamically are supported
by using composite protocols to implement customized instances
of the TS and DS layers for each application.
Each composite protocol is, in turn, composed of finer grain
software modules called micro-protocols that implement
the abstract QoS properties.
Micro-protocols are executed using an event-driven paradigm in
which events are bound to event handlers within micro-protocols.
This approach enhances configurability by decoupling micro-protocols,
thereby allowing execution behavior to be changed by rebinding events
to different event handlers.
Finally, a QoS Manager manages site resources and encapsulates
resource allocation policies.
Overall system coordination of resource allocation and adaptation
policies is realized by peer-to-peer communication between sites, either
between QoS Managers or between the respective TS and DS layers.
The overall goal of this project is to fully develop this framework
by undertaking investigations related to the conceptual underpinnings
and system infrastructure needed to realize this vision.
The specific issues to be pursued can be divided into four categories:
fine-grain QoS attributes, realizing dynamic adaptability, developing
the Cactus prototype system, and experimentation.
The first year goals of the project are:
- Research: Understanding important QoS guarantees and the
relations between them given a fixed resource pool, specification
methods for fine-grain probabilistic and conditional QoS attributes,
and models and algorithms that allow application-specific tradeoffs
between attributes, plus examples of services based on these models.
- Cactus: The basic runtime system for Cactus on a cluster of
PentiumPC's running OSF/RI MK 7.3, together with micro-protocol
suites for selected services in TS and DS layers; an initial version
of Cactus++ executing on a single workstation.
back to Cactus home page
http://www.cs.arizona.edu/cactus/overview.html
Last updated Sept. 18, 1998
Matti Hiltunen
(hiltunen@cs.arizona.edu)