Task Recovery in Self-Organised Multi-Agent Systems for Distributed Domains

Grid computing and cloud systems are distributed systems which provide substantial widely-accessible services to resources. Quality of service is affected by the issues around resource allocation, sharing, task execution and node failure. The focus of this research is on task execution in distributed environments and the effects of node failure on service provision. Most methods in the literature which provide fault tolerance, use reactive techniques; these provide solutions to failure only after its occurrence. In contrast, this research argues that using multi-agent systems with self-organising capabilities can provide a proactive methodology which can improve task execution in open, dynamic and distributed environments. We have modelled a system of autonomous agents with heterogeneous resources and proposed a new delegation protocol for executing tasks within their time constraints. This helps avoid the loss of tasks and to improve efficiency. However, this method on its own is not sufficient in terms of task execution throughput, especially in the presence of agent failure. Hence, we propose, a self-organisation technique. This is represented in this research by two different mechanisms for creating organisations of agents with a certain structure; we suggest, in addition, the adoption of task delegation within the organisations. Adding an organisation structure with agent roles to the network enables smoother performance, increases task execution throughput and copes with agent failures. In addition, we study the failure problem as it manifests within the organisations and we suggest an improvement to the organisation structure which involves the use of another protocol and adding a new role. An exploratory study of dynamic, heterogeneous organisations of agents has also been conducted to understand the formation of organisations in a dynamic environment where agents may fail and new agents may join organisations. These conditions mean that new organisations may evolve and existing organisations may change

Symptoms of complexity in a tourism system

Tourism destinations behave as dynamic evolving complex systems, encompassing numerous factors and activities which are interdependent and whose relationships might be highly nonlinear. Traditional research in this field has looked after a linear approach: variables and relationships are monitored in order to forecast future outcomes with simplified models and to derive implications for management organisations. The limitations of this approach have become apparent in many cases, and several authors claim for a new and different attitude. While complex systems ideas are amongst the most promising interdisciplinary research themes emerged in the last few decades, very little has been done so far in the field of tourism. This paper presents a brief overview of the complexity framework as a means to understand structures, characteristics, relationships, and explores the implications and contributions of the complexity literature on tourism systems. The objective is to allow the reader to gain a deeper appreciation of this point of view.Comment: 32 pages, 3 figures, 1 table; accepted in Tourism Analysi

On Agent-Based Software Engineering

Agent-based computing represents an exciting new synthesis both for Artificial Intelligence (AI) and, more generally, Computer Science. It has the potential to significantly improve the theory and the practice of modeling, designing, and implementing computer systems. Yet, to date, there has been little systematic analysis of what makes the agent-based approach such an appealing and powerful computational model. Moreover, even less effort has been devoted to discussing the inherent disadvantages that stem from adopting an agent-oriented view. Here both sets of issues are explored. The standpoint of this analysis is the role of agent-based software in solving complex, real-world problems. In particular, it will be argued that the development of robust and scalable software systems requires autonomous agents that can complete their objectives while situated in a dynamic and uncertain environment, that can engage in rich, high-level social interactions, and that can operate within flexible organisational structures

The civil and family law needs of Indigenous people in Victoria

This report identifies the most pressing legal needs of Indigenous Victorians, which involve housing, discrimination and debt.The report presents key findings and recommendations of research conducted in 2012- 2013 by the Indigenous Legal Needs Project (ILNP) in Victoria. The ILNP is a national project. Its aims are to:identify and analyse the legal needs of Indigenous communities in non-criminal areas of law (including discrimination, housing and tenancy, child protection, employment, credit and debt, wills and estates, and consumer-related matters); and provide an understanding of how legal service delivery might work more effectively to address identified civil and family law needs of Indigenous communities. ILNP research is intended to benefit Indigenous people by improving access to civil and family law justice

Linking small producers to supermarkets? The role of intermediaries on the fresh fruit and vegetable market in Turkey.

A wide range of the empirical studies shows to what extend the rise of supermarkets in developing countries deeply transform domestic marketing channels. In particular, the exclusion of small producers from the so-called dynamic marketing channels (that is remunerative ones) is at stake. Based on original data collected in Turkey in 2007 at the producer and the wholesale market levels, we show that the intermediaries are decisive in order to understand the impact of downstream restructuring (supermarkets) on upstream decisions (producers). The results show first that producers are not aware of the final buyer of their produce, as intermediaries hinder the visibility of the marketing channel, their choice is restricted to that of the first intermediary. Moreover, the econometric results conclude that producers who are indirectly linked to the supermarkets are more sensitive to their requirements in terms of quality and packaging than to the price premia they set accordingly to the effort made to meet their standards. Therefore, the results question the role of the wholesale market agents who act as a buffer in the chain and protect small producers from negative shocks, but who stop positive shocks as well, and reduce incentives.supermarkets, small farmers, fresh fruit and vegetables, Turkey, Agribusiness, Production Economics, Q13, L14, D24,

Experimenting with Gnutella Communities

Computer networks and distributed systems in general may be regarded as communities where the individual components, be they entire systems, application software or users, interact in a shared environment. Such communities dynamically evolve with components or nodes joning and leaving the system. Their own individual activities affect the community's behaviour and vice-versa. This paper discusses various experiments undertaken to investigate the behaviour of a real system, the Gnutella network, which represents such a community. Gnutella is a distributed Peer-to-Peer data-sharing system without any central control. It turns out that most interactions between nodes do not last long and much of their activity is devoted to finding appropriate partners in the network. Good connections lasting longer appear only as rare events. For example, out of 42,000 connections only 57 hosts were found to available on a regular basis. This means that, in contrast to the common belief that this kind of peer-to-peer networks or sub-communities are always large, they are actually quite small. However, those sub-communities examplify very dynamic behaviour because their actual composition can change very quickly. The experimental results presented have been obtained from a Java implementation of Gnutella running in the open Internet environment, and thus in unknown and quickly changing network structures heavily dependent on chance. Les réseaux informatique ainsi que les systèmes distribués peuvent être considérés comme des communautés où les composantes - que ce soit des systèmes complets, des programmes ou des usagers - interagissent dans un environnement partagé. Ces communautés sont dynamiques car des éléments peuvent s'y joindre ou quitter en tout temps. L'article présente les résultats d'une suite d'expériences et de mesures faites sur Gnutella, un système peer-to-peer à grande échelle qui opère sans aucun contrôle centralisé. Nous avons remarqué qu'une grande partie des messages échangés sont erronés ou redondants et que les interactions entre n?uds ne durent pas très longtemps. En particulier, des connexions durant plus d'une minute sont des phénomènes rares. Les n?uds passent donc la majorité de leur temps à remplacer les partenaires perdus et, contrairement à l'idée répandue que les réseaux peer-to-peer sont immenses, nous avons noté que les communautés effectives étaient assez limitées. Gnutella est un environnement très dynamique avec peu de stabilité. Par exemple, de 42,000 sites avec lesquels nous avons établi une connexion, il a seulement été possible de re-communiquer de façon régulière avec 57. Dans un tel environnement, la chance joue un rôle important dans la performance observée; mais nous avons élaboré un protocole expérimental permettant de comparer diverses options.Gnutella, peer-to-peer networks, Internet communities, distributed systems, protocols, Gnutella, réseaux peer-to-peer, communautés virtuelles, internet, systèmes distribués, protocoles de télécommunication

An exploratory study of factors influencing make-or-buy of sales activities

Purpose This paper aims to explore how sales managers make resourcing decisions with particular focus on their perceptions of outsourcing. Design/methodology/approach This paper is based on in-depth interviews with 29 senior sales managers from a variety of industry sectors based in the UK. All had more than five years’ experience of making resourcing decisions. Findings The findings are that resourcing decisions are prompted by cost pressure, the need to access skills or to improve flexibility. Outsourcing preferences are strongly moderated by perceived reputational risk. Availability of suitable suppliers and the ability to manage outsourcing are also practical moderators. Research limitations/implications The sample was purposeful in identifying and accessing senior respondents in substantial companies with extensive experience, but it was not random. Practical implications Respondents reported a lack of information available when making resourcing decisions; the model proposed provides a framework by which sales managers can identify the factors which should be taken into account and the information they need to make objective evaluations of resourcing options. Originality/value It has been acknowledged in prior literature that there is relatively little outsourcing of sales activities. This is the first exploratory study of the perceptions of sales managers about resourcing options and the first conceptualisation of how sales resourcing decisions are made

Networks Within Cities and Among Cities: A Paradigm for Urban Development and Governance

Networks and networking have become fashionable concepts and terms in regional science, and in particular in regional and urban geography in the last decade: we speak about network firms, network society, network economy but also network cities, city-networks, reti urbane, reseaux de villes. Only catch-words for somebody; a true new scientific paradigm according to others. Our opinion is that in fact we are confronted with a new paradigm in spatial sciences, under some precise conditions: - that its exact meaning is thoroughly defined, - that its theoretical economic rationale is justified, - that the novelty of its empirical content is clearly pointed out, with respect to more traditional spatial facts and processes that can easily be interpreted through existing spatial paradigms. The relevant theoretical building block on which the network concept or paradigm may be constructed are: - a new view of the economy as a system or web of links between individuals, firms and institutions, where links depend on experience and evolve through learning processes; the existing endowment of knowledge and other production factors is put into value through a relational capability addressed towards the exchange and collection of information, building reputation and trust, creating synergies, cutting down uncertainty, boosting learning processes; - the acknowledgement of cooperation as a new organisational and behavioural form, intermediate between hierarchy (internal development and merging of external activities through direct control) and market resort; cooperation networks among firms collaborating with each other on technological advances and innovation projects were the earlier phenomena that were abundantly explored in the past. In a spatial perspective, two phenomena in particular are worth exploring today through the network concept: - networking as cooperation among individuals, firms and institutions taking place inside the cities concerning collective action, public/private partnerships on large urban projects and the supply of public goods, and giving rise to new forms of urban governance; - networking as inter-urban cooperation, assuming the cities as economic actors, competing but also cooperating in the global arena where locations of internationally mobile factors (professionals, corporations, institutions) are decided and negotiated. The paper is organised in the following way: - a major section is devoted to the interpretation of the micro-economic efficiency of local networking (local urban networks), in terms of the usual criteria of optimal allocation of resources and collective welfare, viewing the network as an organisational alternative between market failure and state failure; - a transition section deals with the interpretation of cities, a collective actor at best, as individual/unitary economic actors, given the case for collective action among interest groups, the possibility of defining in broad terms a function of collective preference referring to non-mobile local actors, the engagement of public and private actors in processes of strategic planning and definition of shared visions for the future of the city vis-a-vis mobile actors; - another main section interprets competition and cooperation among cities (inter-city-networks) underlining advantages, risks and conditions for maximising overall comprehensive well-being. JEL classification: D70, H77, R58