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Desempenho em ambiente Web considerando diferenciação de serviços (QoS) em cache, rede e servidor: modelagem e simulação; Performance in Web environments with differentiation of service (QoS) in caches, network and server: modeling and simutation

Abrão, Iran Calixto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/12/2008 Português
Relevância na Pesquisa
47.626333%
Esta tese de doutorado apresenta a investigação de alternativas para melhorar o desempenho de ambientes Web, avaliando o impacto da utilização de mecanismos de diferenciação de serviços em todos os pontos do sistema. Foram criados e modelados no OPNET Modeler cenários com diferentes configurações voltadas tanto para a diferenciação de serviços, quanto para o congestionamento da rede. Foi implementado um servidor cache com suporte à diferenciação de serviços (cache CDF), que constitui uma contribuição dentro deste trabalho, complementando o cenário de diferenciação de serviços de forma positiva, assegurando que os ganhos obtidos em outras etapas do sistema não sejam perdidos no momento da utilização do cache. Os principais resultados obtidos mostram que a diferenciação de serviços introduzida de forma isolada em partes do sistema, pode não gerar os ganhos de desempenho desejados. Todos os equipamentos considerados nos cenários propostos possuem características reais e os modelos utilizados no OPNET foram avaliados e validados pelos seus fabricantes. Assim, os modelos que implementam os cenários considerados constituem também uma contribuição importante deste trabalho, uma vez que o estudo apresentado não se restringe a uma modelagem teórica...

Políticas de atendimento para servidores Web com serviços diferenciados baseadas nas características das requsições; Atttendance politics for Web servers with differentiated services based on the features of Web requests

Traldi, Ottone Alexandre
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/12/2008 Português
Relevância na Pesquisa
37.08396%
Este trabalho propõe mecanismos de diferenciação de serviços para servidores Web, visando a melhorar o desempenho desses sistemas quando são consideradas as características das requisições Web nas políticas de atendimento. Optou-se por adotar o contexto do comércio eletrônico para a realização das pesquisas, uma vez que esse ambiente é um dos mais impactados negativamente quando há um comportamento inadequado do servidor em situações de sobrecarga. Para isso, foi realizada uma investigação das características das requisições Web típicas do e-commerce, para que tais características pudessem ser usadas como diretrizes para os mecanismos e melhorar o desempenho dos servidores. Em seguida, foram propostos um modelo de carga de trabalho e um modelo de simulação para a realização dos experimentos. Com isso, foi possível avaliar os resultados obtidos com a inserção dos diversos mecanismos no Servidor Web com Diferenciação de Serviços (SWDS), um modelo de servidor cuja arquitetura o torna capaz de fornecer serviços diferenciados a seus usuários e aplicações. Foram propostos novos mecanismos de escalonamento de requisições bem como novos mecanismos de controle de admissão. Diversas simulações foram realizadas e os resultados obtidos mostram que a exploração das características das requisições Web...

Mecanismos e formas de acesso à QoS em ambientes Microsoft Windows XP e Windows Server 2003; Mechanisms and means of access to QoS (Quality of Service) in Microsoft Windows XP and Windows Server 2003

Oliveira, Igor Ramos de
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
Português
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Este trabalho visa apresentar um estudo dos métodos e formas de obtenção de qualidade de serviço em redes locais (LANs - Local Area Networks) suportadas pelas plataformas Microsoft Windows XP e Windows Server 2003. Nele, fizemos um breve relato da história das redes de computadores e dos principais eventos ocorridos nos últimos 50 anos que ajudaram a tornar as redes computacionais tão imprescindíveis nos dias de hoje. Também são destacados conceitos importantes relacionados aos mecanismos e tecnologias envolvidos na qualidade de serviço, como métricas e modelos de implementação. Finalmente, são feitos testes e simulações de implementação da qualidade de serviço em um ambiente suportado pela plataforma Windows XP.; This work has as goal to present a study of methods and ways of achieving quality of service in local area networks (LANs) supported by Microsoft Windows XP and Windows Server 2003 platforms. In this document, we made a brief of computer networks history and the main events of the last 50 years that helped make computer networks so essential today. Important concepts related to the mechanisms and technologies involved in the quality of service, such as metrics and implementation models are also highlighted. Finally...

A framework for multi-class-based multicast routing

Nicolau, Maria João; Costa, António; Santos, Alexandre
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 03/06/2002 Português
Relevância na Pesquisa
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The goal of Differentiated Service Architecture is to provide the benefits of different CoS levels while avoiding the limitations of the IntServ model. This is accomplished by aggregating traffic into specific classes, thus changing the scope from QoS (per flow) to CoS (per class) guarantees. In presence of DiffServ networks, per flow path computation is not adequate. Instead, per class path calculation must be made and so multiple paths (unicast routing) or trees (multicast routing), must be computed in order to satisfy the different QoS requirements of different traffic classes. This paper presents a new multicast routing strategy enabling per class multicast tree computation. The proposed heuristics enable directed trees establishment, instead of reverse path ones, due to the importance of link asymmetry within an environment which is, essentially, unidirectional.

Load balancing optimization of telecommunication networks with two differentiated services

Sousa, Amaro Fernandes de; Lopes, Carlos; Santos, Dorabella
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The Differentiated Services architecture is a scalable solution to provide differentiated Quality of Service. In this paper, we address the network load balancing optimization of such networks based on bandwidth differentiation between two services. We define the optimization problem as an Integer Programming model and propose a heuristic algorithm based on GRASP with Path Relinking. We present computational results showing that (i) good quality solutions can be computed and (ii) proper load balancing can efficiently obtain service differentiation.

O caráter educativo do serviço social do comércio.; The educative character of the social service of the commerce.

Nascimento, Adielma Lima do
Fonte: Universidade Federal de Alagoas; BR; Serviço Social; Programa de Pós-Graduação em Serviço Social; UFAL Publicador: Universidade Federal de Alagoas; BR; Serviço Social; Programa de Pós-Graduação em Serviço Social; UFAL
Tipo: Dissertação Formato: application/pdf
Português
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In this work it is argued the relation enters the educative character of the Social Service of the Commerce and the orientações of the politics for control of the work force, as well as the consequences of the assimilation of these orientações for the diligent classroom. For the development of this research, it was used as metodológico resource the bibliographical research and the documentary one. The description-critical perspective was the used theoretical referencial for the accomplishment of the research and the exposition of the studied object. It is defended thesis of that the SESC would have as objective to contribute for the capitalist economic development, guaranteeing way social rendering of services the maintenance and the social control on the diligent classroom of the commerce. Desvelamos that the educative assistance given by the SESC contributes to keep a force of work psicossocialmente adjusted to the period of training of development of the international capital. It is considered that this educative action if inserts in a set of actions directed toward the maintenance of the hegemony of the capital, articulated with the strategies of efetivação of private social politics to reduce the paper and the participation of the State in offers of social services...

Bandwidth allocation for quality of service provision in IEEE 802.16 systems.

Tang, Tze Wei
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009 Português
Relevância na Pesquisa
36.903772%
This thesis investigates various aspects of bandwidth allocation and scheduling in the Medium Access Control (MAC) layer of IEEE 802.16 systems. We highlight the important aspects of designing a scheduler and describe the scheduler design problem from a general perspective. That is, we provide a scheduler design framework driven by a set of objectives defined for the systems. In addition, we include Subscriber Station differentiation into our scheduler design. This approach is comprehensive, as it covers the requirements of both the network provider and the end users. In developing the framework, we discuss the importance of achieving customer satisfaction. This leads to an interesting objective that maximises the number of satisfied customers, rather than network centric objectives, such as fairness. We contend that providing fairness to customers does not necessarily achieve the best outcome for customer satisfaction and artificially limits the choices available to service providers. In order to maximise the number of satisfied customers, we analyse in detail the Dual-Queue (DQ) scheduling discipline proposed by Hayes et al. [2]. The DQ algorithms of Hayes’ work are focused on wireline networks, and are not directly deployable in an 802.16 environment...

Differentiated and predictable quality of service in Web server systems

Aron, Mohit
Fonte: Universidade Rice Publicador: Universidade Rice
Português
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As the World Wide Web experiences increasing commercial and mission-critical use, server systems are expected to deliver high and predictable performance. The phenomenal improvement in microprocessor speeds, coupled with the deployment of clusters of commodity workstations has enabled server systems to meet the continually increasing performance demands in a cost-effective and scalable manner. However, as the volume, variety and sophistication of services offered by server systems increase, effective support for providing differentiated and predictable quality of service has also become important. For example, it is often desirable to differentiate between the resources allocated to virtual web sites hosted on a server system so as to provide predictable performance to individual sites, regardless of the load imposed upon others. Server systems lack adequate support for providing predictable performance to hosted services in terms of metrics that are meaningful to server applications, such as average throughput, response time etc. This is because conventional systems multiplex resources by dealing with system level metrics such as CPU/disk bandwidth, memory pages etc. Maintaining predictable levels of performance in application level metrics...

A Feedback Mechanism for Mitigating Denial of Service Attacks against Differentiated Services Clients

Braun, M.; Xie, Geoffrey
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Português
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Proc. Tenth Int. Conf. on Telecommunication Systems: Modeling and Analysis, pp. 204-213, Monterey, CA, October 2002.; Differentiated Service (DiffServ) networks provide Quality of Service (QoS) guarantees by policing traffic into a fixed number of pre-existing classes. DoS1 attacks against DiffServ clients will be more targeted and require less attack bandwidth than current attacks due to the per-client and per-class bandwidth limitations which must be imposed to ensure QoS guarantees. In this paper, we present a technique for defeating a DoS attack on a DiffServ client through dynamic modification of packet headers. This technique allows the DiffServ network to distinguish valid traffic from malicious traffic, but does not require cryptographic processing on a per-packet basis and does not increase packet size. We also examine the sensitivity of our system to the traffic policerâ s token bucket size.

A method for mitigating denial of service attacks on differentiated services networks

Braun, Matthew J.
Fonte: Monterey, California: Naval Postgraduate School, 2002. Publicador: Monterey, California: Naval Postgraduate School, 2002.
Formato: xiv, 85 p. : ill. (some col.) ; 28 cm.
Português
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Approved for public release; distribution is unlimited; This thesis presents a method for countering Denial of Service (DoS) attacks in networks that provide Quality of Service (QoS) guarantees using Differentiated Service (DiffServ). This approach uses feedback from the DiffServ provider to initiate packet signing at the source. The signature allows the DiffServ provider to distinguish valid packets from malicious packets. This mechanism can also be used to provide key management for other digital signature methods, such as the Internet Protocol Authentication Header (IP AH). However, unlike other methods, our solution requires no encryption or cryptographic processing on a per-packet basis. Instead, it utilizes the sender's ability to alter its packet signatures faster than the attacker can duplicate the changes. This method also avoids the fragmentation and decreased throughput associated with increased packet size of IP AH through use of existing fields in the IP header. This method results in a significant reduction in valid packets that are dropped during a DoS attack. Thus, a DiffServ provider would be able to maintain QoS guarantees during an attack without incurring the overhead associated with cryptographic signatures. A C++ implementation of this DoS countermeasure for the ns2 network simulator and the experimental simulation scripts are included as appendices.; Lieutenant...

Scheduling and management of real-time communication in point-to-point wide area networks

Pope, Cheryl Lynn
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 1345737 bytes; 73076 bytes; application/pdf; application/pdf
Publicado em //2003 Português
Relevância na Pesquisa
36.986658%
Applications with timing requirements, such as multimedia and live multi-user interaction, are becoming more prevalent in wide area networks. The desire to provide more predictable performance for such applications in packet switched wide area networks is evident in the channel management provided by Asynchronous Transfer Mode (ATM) networks and in the extensions to the Internet protocols proposed by the Internet Engineering Task Force (IETF) working groups on integrated and differentiated service. The ability to provide guarantees on the performance of traffic flows, such as packet delay and loss characteristics, relies on an accurate model of the traffic arrival and service at each node in the network. This thesis surveys the work in bounding packet delay based on various proposed queuing disciplines and proposes a method for more accurately defining the traffic arrival and worst case backlog experienced by packets. The methods are applied to the first in first out (FIFO) queuing discipline to define equations for determining the worst case backlog and queuing delay in multihop networks. Simulation results show a significant improvement in the accuracy of the delay bounds over existing bounds published in the literature. An improvement of two orders of magnitude can be realised for a ten hop path and the improvement increases exponentially with the length of the path for variable rate network traffic. The equations derived in the thesis also take into consideration the effect of jitter on delay...

Human agency, power, and discourse: accomplishing farm work through short messaging service (SMS) in the Philippines.

Zagado, Ronan Guanzon
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013 Português
Relevância na Pesquisa
36.903772%
This thesis examines how rice farmers accomplish their farm work using short messaging service (SMS) technology in the Philippines. Currently, sixty percent of rice-farming households in the country use mobile phones, mainly for SMSing. Analysis draws on empirical data to reveal the relationship between new media and agriculture using the Farmers' Text Centre in the Philippines as a case study. The analysis uses a social constructivist framework as its interpretive lens. Results of the study indicate SMSing is central to the accomplishment of farm work. The analysis further reveals that this particular use of SMS in agriculture must take into account the interplay of human agency, power, and discourse. SMSing is found to be constituted and operating not solely according to its technical logic but by the dynamic interplay of the people involved (human agency), their will to achieve outcomes (power), and the system that governs their interaction (discourse). SMSing is seen here as a reflexive phenomenon in that it comes about through a complex process of structuration. Three areas were identified where the reflexive nature of SMSing has become manifest. These are: rice cropping, knowledge production, and farmer’s everyday life. Rice cropping is no longer linked to...

Case Management, Client Risk Factors, and Service Use

Newcomer, Robert; Arnsberger, Pamela; Zhang, Xiulan
Fonte: CENTERS for MEDICARE & MEDICAID SERVICES Publicador: CENTERS for MEDICARE & MEDICAID SERVICES
Tipo: Artigo de Revista Científica
Publicado em //1997 Português
Relevância na Pesquisa
37.042808%
Six “pure” types of case-manager activity are identified using chart data from 922 cases in the Medicare Alzheimer's Disease Demonstration. The association between case-manager actions and client characteristics, and between case-manager activities and service use outcomes is used to test predictive validity. Case-manager activity is generally more associated with caregiver than client characteristics. Monitoring and service management was protective against nursing home placement. A clinical nursing emphasis was protective against hospitalization. Understanding how case management is differentiated may improve staffing, treatment protocol, and client service outcomes.

Design and implementation of a differentiated service based qos model for real-time interactive traffic on constrained bandwidth ip networks

Chaudhuri, Sruti Gan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/05/2012 Português
Relevância na Pesquisa
47.2965%
In this thesis work, a QoS model for real-time interactive traffic on a real network with constrained bandwidth and real-time traffic has been proposed. The model supports tight guarantees of QoS to real-time interactive traffic without over provisioning of bandwidth. A dynamic scheduling model which is adaptive to input data rate of traffic has been proposed. In this model, A Differentiated Service (DiffServ) based approach is proposed for QoS provisioning. The packets are classified and distributed among finite number of queues with limited buffer based on different priorities and total available bandwidth. The model proposes a mechanism to derive the weighted service rates and queue length distribution so as to meet the requirement of low packet loss and delay for real time interactive traffic in the QoS engineered network. An adaptive queuing strategy is proposed so that minimum bandwidth in used for real time traffic. This ensures maximizing availability to best effort traffic. The model assumes constrained bandwidth without having to over provision the network resources and thus keeping the cost low. A modified version suitable for testing on a real network is also presented. Experimental verification of these in a test bed network in a laboratory as well as on a real network has been carried out. The results of the QoS provisioning model for different sources of real-time traffic such as video conferencing equipment...

Service Provisioning and Profit Maximization in Network-assisted Adaptive HTTP Streaming

Yan, Zhisheng; Westphal, Cedric; Wang, Xin; Chen, Chang Wen
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/01/2015 Português
Relevância na Pesquisa
36.903772%
Adaptive HTTP streaming with centralized consideration of multiple streams has gained increasing interest. It poses a special challenge that the interests of both content provider and network operator need to be deliberately balanced. More importantly, the adaptation strategy is required to be flexible enough to be ported to various systems that work under different network environments, QoE levels, and economic objectives. To address these challenges, we propose a Markov Decision Process (MDP) based network-assisted adaptation framework, wherein cost of buffering, significant playback variation, bandwidth management and income of playback are jointly investigated. We then demonstrate its promising service provisioning and maximal profit for a mobile network in which fair or differentiated service is required.; Comment: ICIP 2015 submission

A Paradox for Admission Control of Multiclass Queueing Network with Differentiated Service

Ye, Heng-Qing
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/10/2006 Português
Relevância na Pesquisa
47.352646%
In this paper, we present counter-intuitive examples for the multiclass queueing network system. In the system, each station may serve more than one job class with differentiated service priority, and each job may require service sequentially by more than one service station. In our examples, the network performance is improved even when more workloads are admitted for service.; Comment: 13 pages, 5 figures

Extended Equal Service and Differentiated Service Models for Peer-to-Peer File Sharing

Zhang, Jianwei; Wang, Yongchao; Xing, Wei; Lu, Dongming
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/03/2012 Português
Relevância na Pesquisa
47.686035%
Peer-to-Peer (P2P) systems have proved to be the most effective and popular file sharing applications in recent years. Previous studies mainly focus on the equal service and the differentiated service strategies when peers have no initial data before their download. In an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when peers' initial data distribution satisfies some special conditions, and also show how to minimize the time to get the file to any number of peers. The proposed models can reveal the intrinsic relations among the initial data amount, the size of peer set and the minimum last finish time. By using the models, we can also provide arbitrary degree of differentiated service to a certain number of peers. We believe that our analysis process and achieved theoretical results could provide fundamental insights into studies on bandwidth allocation and data scheduling, and can give helpful reference both for improving system performance and building effective incentive mechanism in P2P file sharing systems.

Towards an SDN Network Control Application for Differentiated Traffic Routing

Adami, Davide; Antichi, Gianni; Garroppo, Rosario G.; Giordano, Stefano; Moore, Andrew W.
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Article; accepted version
Português
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This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/ICC.2015.7249251; In the last years, Software Defined Networking has emerged as a promising paradigm to foster network innovation and address the issues coming from the ossification of the TCP/IP architecture. The clean separation between control and data plane, the definition of northbound and southbound interfaces are key features of the Software Defined Networking paradigm. Moreover, a centralised control plane allows network operators to deploy advanced control and management strategies. Effective traffic engineering and resources management policies allow to achieve a better utilisation of network resources and improve endto- end service performance. This paper deals with the architectural design and experimental validation of a control application that enables differentiated routing for traffic flows belonging to different service classes. The new control application makes routing decisions leveraging on OpenFlow network statistics, i.e., taking advantage of real-time network status information. Moreover, a Deep Packet Inspection module has been developed and integrated in the control application to detect VoIP traffic with Session Initiation Protocol signalling...

Effective management of EFL(Executive Floor): An Investigation into quality-management on service

Kim, Keon-Wuk
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
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In a recent days the hotel industries, coping with the change of management environment swiftly, are turning to pursue the quality-management of service. The merchandises of hotel are fundamentally rooms, food and beverage, and subsidiary facilities. The hotel in modern times, laying stress on service radically, have being endeavored to minimize the difference between the actual service offered and the expectation of customers on it. Especially because of the essential qualities in hotel, the need of quality-management is demanded to increase. The EFL in hotel is not only the place where the difficulty of producing the merchandise focused on quality is reflected but also the department in which the endeavor of keeping up the service quality and the effective quality-management is demanded. The study on the quality-management, however, is not enough to satisfy the customers and the men engaging in hotels as well as the scholars. The purpose of this study are follows ; 1 . To disclose the signification of EFL in hotel management through the investigation into the conception, the importance and the character of EFL. 2. To know how to control the human resources to realize the improvement the quality service for customers and the quality-management of EFL in hotel. 3. To search the management and problem of EFL in hotel. Therefore...

A experiência de um serviço de saúde especializado no atendimento a pacientes indígenas; The experience of a specialized health service for the care of Indian patients

Pereira, Érica Ribeiro; Biruel, Elisabeth Peres; Oliveira, Lavínia Santos de Souza; Rodrigues, Douglas Antônio
Fonte: Universidade de São Paulo. Faculdade de Saúde Pública Publicador: Universidade de São Paulo. Faculdade de Saúde Pública
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/09/2014 Português
Relevância na Pesquisa
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A descriptive study, of qualitative nature, in the modality of experience report. A paper developed in a specialized health service for the care of Indian patients, based on university extension activities of users’ reception, health promotion and education. The Indian outpatients clinic and São Paulo’s Hospital, of the Federal University of São Paulo, are references in medium and high complexity service to Indian populations in several regions in Brazil. The extension projects were intended to create conversation spaces, to identify perceptions about the health-disease process and to establish a health care project, from the identification of the indigenous patient needs. The proposal of forming bonds with Indian patients that go beyond the objective of solving a health problem to enter the interfaces among health, culture and life style was a challenge for the health staff. It can be concluded that the outpatient clinic of the Indian is a permanent space for reflection, for a differentiated service to these patients in the areas of health assistance, teaching, research and extension.; Estudo descritivo, de natureza qualitativa, na modalidade de relato de experiência. Trabalho desenvolvido em serviço de saúde especializado no atendimento a pacientes indígenas a partir de atividades de extensão universitária em acolhimento...