Dynamic management and restoration of virtual paths in broadband networks based on distributed software agents

La gestió de xarxes és un camp molt ampli i inclou molts aspectes diferents. Aquesta tesi doctoral està centrada en la gestió dels recursos en les xarxes de banda ampla que disposin de mecanismes per fer reserves de recursos, com per exemple Asynchronous Transfer Mode (ATM) o Multi-Protocol Label Switching (MPLS). Es poden establir xarxes lògiques utilitzant els Virtual Paths (VP) d'ATM o els Label Switched Paths (LSP) de MPLS, als que anomenem genèricament camins lògics. Els usuaris de la xarxa utilitzen doncs aquests camins lògics, que poden tenir recursos assignats, per establir les seves comunicacions. A més, els camins lògics són molt flexibles i les seves característiques es poden canviar dinàmicament. Aquest treball, se centra, en particular, en la gestió dinàmica d'aquesta xarxa lògica per tal de maximitzar-ne el rendiment i adaptar-la a les connexions ofertes. En aquest escenari, hi ha diversos mecanismes que poden afectar i modificar les característiques dels camins lògics (ample de banda, ruta, etc.). Aquests mecanismes inclouen els de balanceig de la càrrega (reassignació d'ample de banda i reencaminament) i els de restauració de fallades (ús de camins lògics de backup). Aquests dos mecanismes poden modificar la xarxa lògica i gestionar els recursos (ample de banda) dels enllaços físics. Per tant, existeix la necessitat de coordinar aquests mecanismes per evitar possibles interferències. La gestió de recursos convencional que fa ús de la xarxa lògica, recalcula periòdicament (per exemple cada hora o cada dia) tota la xarxa lògica d'una forma centralitzada. Això introdueix el problema que els reajustaments de la xarxa lògica no es realitzen en el moment en què realment hi ha problemes. D'altra banda també introdueix la necessitat de mantenir una visió centralitzada de tota la xarxa. En aquesta tesi, es proposa una arquitectura distribuïda basada en un sistema multi agent. L'objectiu principal d'aquesta arquitectura és realitzar de forma conjunta i coordinada la gestió de recursos a nivell de xarxa lògica, integrant els mecanismes de reajustament d'ample de banda amb els mecanismes de restauració preplanejada, inclosa la gestió de l'ample de banda reservada per a la restauració. Es proposa que aquesta gestió es porti a terme d'una forma contínua, no periòdica, actuant quan es detecta el problema (quan un camí lògic està congestionat, o sigui, quan està rebutjant peticions de connexió dels usuaris perquè està saturat) i d'una forma completament distribuïda, o sigui, sense mantenir una visió global de la xarxa. Així doncs, l'arquitectura proposada realitza petits rearranjaments a la xarxa lògica adaptant-la d'una forma contínua a la demanda dels usuaris. L'arquitectura proposada també té en consideració altres objectius com l'escalabilitat, la modularitat, la robustesa, la flexibilitat i la simplicitat. El sistema multi agent proposat està estructurat en dues capes d'agents: els agents de monitorització (M) i els de rendiment (P). Aquests agents estan situats en els diferents nodes de la xarxa: hi ha un agent P i diversos agents M a cada node; aquests últims subordinats als P. Per tant l'arquitectura proposada es pot veure com una jerarquia d'agents. Cada agent és responsable de monitoritzar i controlar els recursos als que està assignat. S'han realitzat diferents experiments utilitzant un simulador distribuït a nivell de connexió proposat per nosaltres mateixos. Els resultats mostren que l'arquitectura proposada és capaç de realitzar les tasques assignades de detecció de la congestió, reassignació dinàmica d'ample de banda i reencaminament d'una forma coordinada amb els mecanismes de restauració preplanejada i gestió de l'ample de banda reservat per la restauració. L'arquitectura distribuïda ofereix una escalabilitat i robustesa acceptables gràcies a la seva flexibilitat i modularitat.

A follow-up study of characteristics of young people that dropout and continue psychotherapy: service implications for a clinic in the community

Background: The paper reports the findings from a follow-up study of the factors that contribute to whether young people dropout or continue once-weekly psychotherapy at a voluntary sector psychotherapy service for young people aged 12 to 21 years. Method: The study uses data from an ongoing audit of the psychotherapy service that started in 1993; 882 young people were included in the study. Premature termination of treatment was defined as dropping out before the 21st session. Continuation in treatment was defined as remaining in therapy after 20 sessions. Measures and areas of interest used in the study include diagnostic measures, the Youth Self Report Form and Young Adult Self Report Form, demographic characteristics and treatment related information. Results: Young people who continued in treatment were more likely to be older, have anxieties about sexual and relationship issues and have higher scores on self-reported anxiety-depression. Young people who dropped out of treatment were more likely to be younger, have higher self-reported delinquency scores, have a diagnosis of hyperactivity-conduct disorder and be homeless. Conclusions: The study of treatment termination has demonstrated the value of service audit and has led to a significant change in clinical practice.

Modelling requirements of supplier selection for benchmarking service provision

Supplier selection has a great impact on supply chain management. The quality of supplier selection also affects profitability of organisations which work in the supply chain. As suppliers can provide variety of services and customers demand higher quality of service provision, the organisation is facing challenges for making the right choice of supplier for the right needs. The existing methods for supplier selection, such as data envelopment analysis (DEA) and analytical hierarchy process (AHP) can automatically perform selection of competitive suppliers and further decide winning supplier(s). However, these methods are not capable of determining the right selection criteria which should be derived from the business strategy. An ontology model described in this paper integrates the strengths of DEA and AHP with new mechanisms which ensure the right supplier to be selected by the right criteria for the right customer's needs.

Distributed multimedia quality: the user perspective

Distributed multimedia supports a symbiotic infotainment duality, i.e. the ability to transfer information to the user, yet also provide the user with a level of satisfaction. As multimedia is ultimately produced for the education and / or enjoyment of viewers, the user’s-perspective concerning the presentation quality is surely of equal importance as objective Quality of Service (QoS) technical parameters, to defining distributed multimedia quality. In order to extensively measure the user-perspective of multimedia video quality, we introduce an extended model of distributed multimedia quality that segregates quality into three discrete levels: the network-level, the media-level and content-level, using two distinct quality perspectives: the user-perspective and the technical-perspective. Since experimental questionnaires do not provide continuous monitoring of user attention, eye tracking was used in our study in order to provide a better understanding of the role that the human element plays in the reception, analysis and synthesis of multimedia data. Results showed that video content adaptation, results in disparity in user video eye-paths when: i) no single / obvious point of focus exists; or ii) when the point of attention changes dramatically. Accordingly, appropriate technical- and user-perspective parameter adaptation is implemented, for all quality abstractions of our model, i.e. network-level (via simulated delay and jitter), media-level (via a technical- and user-perspective manipulated region-of-interest attentive display) and content-level (via display-type and video clip-type). Our work has shown that user perception of distributed multimedia quality cannot be achieved by means of purely technical-perspective QoS parameter adaptation.

Enforcing service level agreements using an economically enhanced resource manager

Traditional resource management has had as its main objective the optimisation of throughput, based on parameters such as CPU, memory, and network bandwidth. With the appearance of Grid Markets, new variables that determine economic expenditure, benefit and opportunity must be taken into account. The SORMA project aims to allow resource owners and consumers to exploit market mechanisms to sell and buy resources across the Grid. SORMA’s motivation is to achieve efficient resource utilisation by maximising revenue for resource providers, and minimising the cost of resource consumption within a market environment. An overriding factor in Grid markets is the need to ensure that desired Quality of Service levels meet the expectations of market participants. This paper explains the proposed use of an Economically Enhanced Resource Manager (EERM) for resource provisioning based on economic models. In particular, this paper describes techniques used by the EERM to support revenue maximisation across multiple Service Level Agreements.

Key drivers of frontline employee generation of ideas for customer service improvement

Anchored in the service-dominant logic and service innovation literature, this study investigates the drivers of employee generation of ideas for service improvement (GISI). Employee GISI focuses on customer needs and providing the exact service wanted by customers. GISI should enhance competitive advantage and organizational success (cf. Berry et al. 2006; Wang and Netemeyer 2004). Despite its importance, there is little research on the idea generation stage of the service development process (Chai, Zhang, and Tan 2005). This study contributes to the service field by providing the first empirical evaluation of the drivers of GISI. It also investigates a new explanatory determinant of reading of customer needs, namely, perceived organizational support (POS), and an outcome of POS, in the form of emotional exhaustion. Results show that the major driver of GISI is reading of customer needs by employees followed by affective organizational commitment and job satisfaction. This research provides several new and important insights for service management practice by suggesting that special care should be put into selecting and recruiting employees who have the ability to read customer needs. Additionally, organizations should invest in creating work environments that encourage and reward the flow of ideas for service improvement

A Unified Load Generator for Geographically Distributed Generation ofNetwork Traffic

During the last decade, the Internet usage has been growing at an enormous rate which has beenaccompanied by the developments of network applications (e.g., video conference, audio/videostreaming, E-learning, E-Commerce and real-time applications) and allows several types ofinformation including data, voice, picture and media streaming. While end-users are demandingvery high quality of service (QoS) from their service providers, network undergoes a complex trafficwhich leads the transmission bottlenecks. Considerable effort has been made to study thecharacteristics and the behavior of the Internet. Simulation modeling of computer networkcongestion is a profitable and effective technique which fulfills the requirements to evaluate theperformance and QoS of networks. To simulate a single congested link, simulation is run with asingle load generator while for a larger simulation with complex traffic, where the nodes are spreadacross different geographical locations generating distributed artificial loads is indispensable. Onesolution is to elaborate a load generation system based on master/slave architecture.

The concept of e-service from a social interaction perspective

Today’s e-services are complex phenomenon consisting of several different e-services linked together. The e-services are provided by IT systems and presented to customers through user interfaces. Within web design research criteria are laid out for the design of good user interfaces, but one problem is that these analyses are performed without a service focus. This lack of service focus can result in the designed user interfaces providing indistinct service concepts, especially where several e-services are intertwined with each other.In order to design IT system interfaces, we have to be clear about which e-services are provided by the IT system and how these e-services are related to each other. This paper presents a framework for the analysis of user interfaces in terms of focused e-service, service environment and two types of intertwined e-services; related e-services and interrelating e-services. The analyses are exemplified by an Internet based e-marketplace. The paper discusses how the framework can be combined with ordinary web design criteria and how it can be used for e-service development.

Intercultural service encounters : an exploratory study of customer experiences

Intercultural contact occurs on a daily basis across all facets of life, and is reflective of Australia’s multicultural society. This trend is observed in many Western industrialised nations and has contributed to a growing body of research and literature in the field of managing cultural diversity. While much of this research is focused on the internal context of the workplace, relatively little attention has been given to the impact of culture on the service provider and customer interface. In an effort to shed some light on the service experiences of culturally diverse customers, a series of exploratory interviews were conducted. The findings suggest that on the basis of service provider behaviors (both verbal and nonverbal), culturally diverse customers perceive they are the recipients of inequitable service and consequently experience low levels of satisfaction.

Agents and the Grid: Service Discovery

The Grid is a large-scale computer system that is capable of coordinating resources that are not subject to centralised control, whilst using standard, open, general-purpose protocols and interfaces, and delivering non-trivial qualities of service. In this chapter, we argue that Grid applications very strongly suggest the use of agent-based computing, and we review key uses of agent technologies in Grids: user agents, able to customize and personalise data; agent communication languages offering a generic and portable communication medium; and negotiation allowing multiple distributed entities to reach service level agreements. In the second part of the chapter, we focus on Grid service discovery, which we have identified as a prime candidate for use of agent technologies: we show that Grid-services need to be located via personalised, semantic-rich discovery processes, which must rely on the storage of arbitrary metadata about services that originates from both service providers and service users. We present UDDI-MT, an extension to the standard UDDI service directory approach that supports the storage of such metadata via a tunnelling technique that ties the metadata store to the original UDDI directory. The outcome is a flexible service registry which is compatible with existing standards and also provides metadata-enhanced service discovery.

Chained Negotiation for Distributed Notification Services

Distributed notification services allow consumers and publishers of notifications to interact with different notification services. However, such a distributed infrastructure makes it difficult to share notifications between consumers when consumers are allowed to specify Quality of Service levels. In this paper, we present a chained negotiation engine, enabling distributed notification services to support negotiation and to reuse existing subscriptions. We demonstrate the benefit to the system as a whole by reducing load on service providers and enabling content to be shared.

Conceptualizing the ιnfluence of the self-service technology context on consumer voice

The self-service technology (SST) context is characterized by consumer participation in service production and delivery, independent of service personnel; a lack of interpersonal interaction between consumers and service personnel; and consumers being required tointerface and interact with technology. With these features of the SST context in mind, in situations where SSTs fail to perform as promised, some challenges arise: consumers who are dissatisfied do not have the security or reassurance of service personnel to assist them; service personnel do not have the opportunity to prompt consumers to voice their dissatisfaction; and consumers need to initiate their own complaint response. If consumers fail to report their dissatisfaction directly to the organization, organizations will not know that a problem exists and may experience negative consequences such as consumer switching behavior. As reports of consumer dissatisfaction with SSTs become increasingly common, it is important, therefore, to investigate how organizations with SST-based offerings can encourage consumers to voice their dissatisfaction directly to the organization. Although the antecedents of consumer voice are well documented in the interpersonal services context, in the context of SSTs they have been subject to very little conceptual or empirical scrutiny. This paper argues that voice needs to be revisited with respect to SSTs due to their unique characteristics compared to interpersonal services, and presents a conceptual model of the antecedents of consumers' voice behavior in the context of SSTs.

Efficient Multi-Granularity Service Composition

Dynamic composition of services provides the ability to build complex distributed applications at run time by combining existing services, thus coping with a large variety of complex requirements that cannot be met by individual services alone. However, with the increasing amount of available services that differ in granularity (amount of functionality provided) and qualities, selecting the best combination of services becomes very complex. In response, this paper addresses the challenges of service selection, and makes a twofold contribution. First, a rich representation of compositional planning knowledge is provided, allowing the expression of multiple decompositions of tasks at arbitrary levels of granularity. Second, two distinct search space reduction techniques are introduced, the application of which, prior to performing service selection, results in significant improvement in selection performance in terms of execution time, which is demonstrated via experimental results.

An exploration of relational customers` response to service failure

Purpose – The purpose of this paper is to examine how customers with different relational bonds respond to the same service failure. In particular, the framework to service failure and recovery devised by Fournier and Mick is applied.
Design/methodology/approach – To uncover rich emotional and cognitive responses to service failure, in-depth interviews with eight former and current patrons of an Australian opera were used.
Findings – Three types of relationship were identified: satisfaction-as-love (SaL), satisfaction-as-trust (SaT) and satisfaction-as-control (SaC). Each responded to the same failure in different ways. SaL customers had emotional bonds with the product category and thus reaffiremed their loyalty following the failure. SaT customers saw the service failure and inadequate recovery as a breach of the brand's implied promise and thus excited the relationship. SaC customers took charge of the situation, using their status to improve their situation and then defended the brand.
Practical implications – The findings indicate the importance of customizing service recovery strategies, in this case to those customers with the strongest emotional bonds to the brand, not the product class.
Originality/value – This is the first paper to examine how relational customers respond to service failure and identify how different customer-brand relationships result in different post-failure reactions and expectations of service recovery.

Enabling successful web-based information technology support for enterprise customers: a service provider perspective of stakeholder-based issues

An understanding by support organisations of the key factors enabling successful enterprise after-sales customer support provision when using Web-based Selfservice Systems (WSSs) is essential to making  improvements in such systems. This paper reports key stakeholder-oriented findings from an interpretive study of critical success factors (CSFs) for the transfer of after-sales support-oriented knowledge from an information technology (IT) service provider to enterprise customers when a WSS is used. The findings suggest that researchers and practitioners should consider WSSs within a complex network of service providers, business partners and customer firms. The paper also clearly points to a need for support organisations to engage in greater collaboration and integration of WSSs with enterprise customers and business partners.