17-03-2014, 10:57 AM
Abstract
Virtual organizations in large-scale distributed environments
can organize their communication in a hierarchical
topology (i.e., trees). However, such topologies can be unreliable
as local failures have a global impact in the organization.
Hierarchical topologies need to adapt continuously
to changes of the underlying environment. Pro-active and
re-active self-organization can make such topologies highly
robust.
This paper proposes AETOS, the Adaptive Epidemic Tree
Overlay Service. AETOS is a new agent-based approach
for building and maintaining on-demand robust tree topologies
that structure communication. Agents are pro-actively
(self)-organized appropriately in a tree to minimize the effect
of failures. In addition, they re-actively rewire their
connections to reflect changes in the environment. The selforganization
model, the control of the system and an illustrative
example are discussed in this paper.
1 Introduction
Hierarchical virtual topologies that define the communication
structures over unreliable large-scale distributed infrastructures,
require robustness. These topologies can be
used in a wide range of applications [5, 9, 13, 14, 15].
Robustness refers to the fact that the hierarchical topology
must be dynamic, adaptive, reconfigurable and finally selforganized
to (i) handle the changes of the underlying distributed
environment and (ii) reflect the application requirements.
Software agents have been proposed as a paradigm
for management of distributed systems [12]. Selfhealing
of hierarchical structures [3] and agent-based selforganization
[16] appear in various approaches of distributed
self-management.Adaptive central control of hierarchical topologies for
communication is not always an option nor a scalable solution.
This is especially the case in the aforementioned largescale
distributed environments. Building and maintaining
robust hierarchical topologies in a distributed manner is the
challenge this paper addresses. Local intelligent software
agents play a central role in acquiring a global hierarchical
topology using their ability to cooperate, adapt [4] and
reconfigure. Local agent behavior can make the topology
self-organizing.
This paper focuses on tree topologies as an instance of
hierarchical structures. In trees, local failures have a global
impact in the topology as the removal of a node disconnects
the branches underneath from the main body of the tree.
Creating self-organized tree topologies that are resilient to
failures requires: (i) to pro-actively organize (sort) agents
over the tree in such a way that a potential failure has minimum
impact on the tree structure, (ii) to re-actively adapt
to changes in the environment by reconnecting, in case of
failures, or rewiring connections to improve the robustness
of the topology.
These are the two main concepts of AETOS, the Adaptive
Epidemic Tree Overlay Service. AETOS is the mechanism
that this paper proposes to build and maintain robust tree
topologies in distributed environments. It is based on a 3-
layer architecture as the core of self-organization. These
three layers are facilitated and managed by a local software
agent, the AETOS agent. Applications can be build on top
of this agent-based dynamic tree overlay. The interaction
between the AETOS agent and the application is managed
through another local agent, the AETOS proxy. This agent
provides the tree overlay on-demand to the application, and
is responsible for bootstrapping and terminating the selforganization
process.
The contribution of this work is three-fold. This paper
proposes the following:
Virtual organizations in large-scale distributed environments
can organize their communication in a hierarchical
topology (i.e., trees). However, such topologies can be unreliable
as local failures have a global impact in the organization.
Hierarchical topologies need to adapt continuously
to changes of the underlying environment. Pro-active and
re-active self-organization can make such topologies highly
robust.
This paper proposes AETOS, the Adaptive Epidemic Tree
Overlay Service. AETOS is a new agent-based approach
for building and maintaining on-demand robust tree topologies
that structure communication. Agents are pro-actively
(self)-organized appropriately in a tree to minimize the effect
of failures. In addition, they re-actively rewire their
connections to reflect changes in the environment. The selforganization
model, the control of the system and an illustrative
example are discussed in this paper.
1 Introduction
Hierarchical virtual topologies that define the communication
structures over unreliable large-scale distributed infrastructures,
require robustness. These topologies can be
used in a wide range of applications [5, 9, 13, 14, 15].
Robustness refers to the fact that the hierarchical topology
must be dynamic, adaptive, reconfigurable and finally selforganized
to (i) handle the changes of the underlying distributed
environment and (ii) reflect the application requirements.
Software agents have been proposed as a paradigm
for management of distributed systems [12]. Selfhealing
of hierarchical structures [3] and agent-based selforganization
[16] appear in various approaches of distributed
self-management.Adaptive central control of hierarchical topologies for
communication is not always an option nor a scalable solution.
This is especially the case in the aforementioned largescale
distributed environments. Building and maintaining
robust hierarchical topologies in a distributed manner is the
challenge this paper addresses. Local intelligent software
agents play a central role in acquiring a global hierarchical
topology using their ability to cooperate, adapt [4] and
reconfigure. Local agent behavior can make the topology
self-organizing.
This paper focuses on tree topologies as an instance of
hierarchical structures. In trees, local failures have a global
impact in the topology as the removal of a node disconnects
the branches underneath from the main body of the tree.
Creating self-organized tree topologies that are resilient to
failures requires: (i) to pro-actively organize (sort) agents
over the tree in such a way that a potential failure has minimum
impact on the tree structure, (ii) to re-actively adapt
to changes in the environment by reconnecting, in case of
failures, or rewiring connections to improve the robustness
of the topology.
These are the two main concepts of AETOS, the Adaptive
Epidemic Tree Overlay Service. AETOS is the mechanism
that this paper proposes to build and maintain robust tree
topologies in distributed environments. It is based on a 3-
layer architecture as the core of self-organization. These
three layers are facilitated and managed by a local software
agent, the AETOS agent. Applications can be build on top
of this agent-based dynamic tree overlay. The interaction
between the AETOS agent and the application is managed
through another local agent, the AETOS proxy. This agent
provides the tree overlay on-demand to the application, and
is responsible for bootstrapping and terminating the selforganization
process.
The contribution of this work is three-fold. This paper
proposes the following: