Policy hierarchies for distributed systems management

Distributed system management, involves monitoring the activity of a system, making management decisions and performing control actions to modify the behavior of the system. Most of the research on management has concentrated on management mechanisms related to network management or operating systems. However, in order to automate the management of very large distributed systems, it is necessary to be able to represent and manipulate management policy within the system. These objectives are typically set out in the form of general policies which require detailed interpretation by the system managers. The paper explores the refinement of general high-level policies into a number of more specific policies to form a policy hierarchy in which each policy in the hierarchy represents, to its maker, his plans to meet his objectives and, to its subject, the objectives which he must plan to meet. Management action policies are introduced, and the distinction between imperatival and authority policies is made. The relationship of hierarchies of imperatival policies to responsibility, and to authority policies, is discussed. An outline approach to the provision of automated support for the analysis of policy hierarchies is provided, by means of a more formal definition of policy hierarchy refinement relationships in Prolog     

Federating Policy-Driven Autonomous Systems: Interaction Specification and Management Patterns

Ubiquitous systems and applications involve interactions between multiple autonomous entities—for example, robots in a mobile ad-hoc network collaborating to achieve a goal, communications between teams of emergency workers involved in disaster relief operations or interactions between patients’ and healthcare workers’ mobile devices. We have previously proposed the Self-Managed Cell (SMC) as an architectural pattern for managing autonomous ubiquitous systems that comprise both hardware and software components and that implement policy-based adaptation strategies. We have also shown how basic management interactions between autonomous SMCs can be realised through exchanges of notifications and policies, to effectively program management and context-aware adaptations. We present here how autonomous SMCs can be composed and federated into complex structures through the systematic composition of interaction patterns. By composing simpler abstractions as building blocks of more complex interactions it is possible to leverage commonalities across the structural, control and communication views to manage a broad variety of composite autonomous systems including peer-to-peer collaborations, federations and aggregations with varying degrees of devolution of control. Although the approach is more broadly applicable, we focus on systems where declarative policies are used to specify adaptation and on context-aware ubiquitous systems that present some degree of autonomy in the physical world, such as body sensor networks and autonomous vehicles. Finally, we present a formalisation of our model that allows a rigorous verification of the properties satisfied by the SMC interactions before policies are deployed in physical devices.     

An Adaptive Policy-Based Framework for Network Services Management

This paper presents a framework for specifying policies for the management of network services. Although policy-based management has been the subject of considerable research, proposed solutions are often restricted to condition-action rules, where conditions are matched against incoming traffic flows. This results in static policy configurations where manual intervention is required to cater for configuration changes and to enable policy deployment. The framework presented in this paper supports automated policy deployment and flexible event triggers to permit dynamic policy configuration. While current research focuses mostly on rules for low-level device configuration, significant challenges remain to be addressed in order to:a) provide policy specification and adaptation across different abstraction layers; and, b) provide tools and services for the engineering of policy-driven systems. In particular, this paper focuses on solutions for dynamic adaptation of policies in response to changes within the managed environment. Policy adaptation includes both dynamically changing policy parameters and reconfiguring the policy objects. Access control for network services is also discussed.     

Policy conflict analysis for diffserv quality of service management

Policy-based management provides the ability to (re-)configure differentiated services networks so that desired Quality of Service (QoS) goals are achieved. This requires implementing network provisioning decisions, performing admission control, and adapting bandwidth allocation to emerging traffic demands. A policy-based approach facilitates flexibility and adaptability as policies can be dynamically changed without modifying the underlying implementation. However, inconsistencies may arise in the policy specification. In this paper we provide a comprehensive set of QoS policies for managing Differentiated Services (DiffServ) networks, and classify the possible conflicts that can arise between them. We demonstrate the use of Event Calculus and formal reasoning for the analysis of both static and dynamic conflicts in a semi-automated fashion. In addition, we present a conflict analysis tool that provides network administrators with a user-friendly environment for determining and resolving potential inconsistencies. The tool has been extensively tested with large numbers of policies over a range of conflict types.     

The empirical case for two systems of reasoning.

Distinctions have been proposed between systems of reasoning for centuries. This article distills properties shared by many of these distinctions and characterizes the resulting systems in light of recent findings and theoretical developments. One system is associative because its computations reflect similarity structure and relations of temporal contiguity. The other is "rule based" because it operates on symbolic structures that have logical content and variables and because its computations have the properties that are normally assigned to rules. The systems serve complementary functions and can simultaneously generate different solutions to a reasoning problem. The rule-based system can suppress the associative system but not completely inhibit it. The article reviews evidence in favor of the distinction and its characterization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forgetting in primed fragment completion.

Seven experiments examined the time course of primed fragment-completion performance. A pilot experiment and Experiment 1 showed that rapid forgetting occurs immediately after study for a period of approximately 5 min. The rate of this immediate forgetting is independent of the length of the list. Experiment 2 showed that priming effects were still present after 16 months. Experiments 3 and 4 provided further evidence of forgetting over 1 week. Experiment 5 showed that retention performance after 20 min is unaffected by the interpolated study and recall of other lists of words. Experiment 6 showed that 10-min retention performance was substantially reduced as list length was increased from 10 to 100 words; but it showed no evidence of intralist proactive interference. The combined results of the seven experiments illustrate some similarities and differences between forgetting in primed fragment completion and in episodic memory tasks such as recall and recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of attractiveness and mate selection in phylogenetic adaptation with particular reference to early man

The author hypothesizes on the roles of sexual selection and assortative mating in human evolution. Basing his argument on a theory, which views neurosis as a maladaptive vicious cycle, he argues that there is dovetailing of the actions of neurosis and mate selection in promoting the phylogenetic adaptation of early man. He sees both neurosis and assortative mating as magnifying existing differences in viability. This process would, by favoring the most viable, have accelerated human evolution. The relationship between movement patterns and neurosis is also discussed.     

Application-level Programmable Internetwork Environment

Future requirements for a broadband multimedia network are likely to be very different from those today. Three key changes are identified — rapid introduction of new services, dynamic customisation of services by clients, and minimal management overhead. Application-layer active networking, perhaps the most pragmatic and immediately realisable active network proposal, is a potential solution to all three. In the 'Management of Multiservice Networks' project, BT and its academic partners are developing key middleware components required to support application-layer active networking.