Websites are shifting from static model to dynamic model, in order to deliver their users with dynamic, interactive, and personalized experiences. However, dynamic content generation comes at a cost – each request requires computation as well as communication across multiple components within the website and across the Internet. In fact, dynamic pages are constructed on the fly, on demand. Due to their construction overheads and non-cacheability, dynamic pages result in substantially increased user response times, server load and increased bandwidth consumption, as compared to static pages. With the exponential growth of Internet traffic and with websites becoming increasingly complex, performance and scalability have become major bottlenecks for dynamic websites. A variety of strategies have been proposed to address these issues. Many of these solutions perform well in their individual contexts, but have not been analyzed in an integrated fashion. In our work, we have carried out a study of combining a carefully chosen set of these approaches and analyzed their behavior. Specifically, we consider solutions based on the recently-proposed fragment caching technique, since it ensures both correctness and freshness of page contents. We have developed mechanisms for reducing bandwidth consumption and dynamic page construction overheads by integrating fragment caching with various techniques such as proxy-based caching of dynamic contents, pre-generating pages, and caching program code. We start with presenting a dynamic proxy caching technique that combines the benefits of both proxy-based and server-side caching approaches, without suffering from their individual limitations. This technique concentrates on reducing the bandwidth consumption due to dynamic web pages. Then, we move on to presenting mechanisms for reducing dynamic page construction times -- during normal loading, this is done through a hybrid technique of fragment caching and page pre-generation, utilizing the excess capacity with which web servers are typically provisioned to handle peak loads. During peak loading, this is achieved by integrating fragment-caching and code-caching, optionally augmented with page pre-generation. In summary, we present a variety of methods for integrating existing solutions for serving dynamic web pages with the goal of achieving reduced bandwidth consumption from the web infrastructure perspective, and reduced page construction times from user perspective.

Orientadores: Sandro Rigo, Reinaldo Alvarenga Bergamaschi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-24T00:17:07Z (GMT). No. of bitstreams: 1 Piga_LeonardodePaulaRosa_D.pdf: 5566406 bytes, checksum: 5fcce79bb9fc83646106c7580e0d77fc (MD5) Previous issue date: 2013 / Resumo: Para acompanhar uma demanda crescente pelos recursos computacionais, empresas de TI precisaram construir instalações que comportam centenas de milhares de computadores chamadas centro de dados. Este ambiente é altamente dependente de energia elétrica, um recurso que é cada vez mais caro e escasso. Neste contexto, esta tese apresenta uma abordagem para otimizar potência e desempenho em centro de dados Web. Para isto, apresentamos uma infraestrutura para medir a potência dissipada por computadores de prateleiras, desenvolvemos modelos empíricos que estimam a potência de servidores Web e, por fim, implementamos uma de nossas heurísticas de otimização de potência global em um aglomerado de nós de processamento chamado AMD SeaMicro SM15k. A infraestrutura de medição de potência é composta por: uma placa personalizada, que é capaz de medir potência e é instalada em computadores de prateleira; um conversor de dados analógico/digital que amostra os valores de potência; e um software controlador. Mostramos uma nova metodologia para o desenvolvimento de modelos de potência para servidores Web que diminuem a quantidade de parâmetros dos modelos e reduzem as relações não lineares entre medidas de desempenho e potência do sistema. Avaliamos a nossa metodologia em dois servidores Web, um constituído por um processador AMD Opteron e outro por processador Intel i7. Nossos melhores modelos tem erro médio absoluto de 1,92% e noventa percentil para o erro absoluto de 2,66% para o sistema com processador Intel i7. O erro médio para o sistema composto pelo processador AMD Opteron é de 1,46% e o noventa percentil para o erro absoluto é igual a 2,08%. A implantação do sistema de otimização de potência global foi feita em um aglomerado de nós de processamento SeaMicro SM15k. A implementação se baseia no conceito de Virtual Power States, uma combinação de taxa de utilização de CPU com os estados de potência P e C disponíveis em processadores modernos, e no nosso algoritmo de otimização chamado Slack Recovery. Propomos e implementamos também um novo mecanismo capaz de controlar a utilização da CPU. Nossos resultados experimentais mostram que o nosso sistema de otimização pode reduzir o consumo de potência em até 16% quando comparado com o governador de potência do Linux chamado performance e em até 6,7% quando comparado com outro governador de potência do Linux chamado ondemand / Abstract: To keep up with an increasing demand for computational resources, IT companies need to build facilities that host hundreds of thousands of computers, the data centers. This environment is highly dependent on electrical energy, a resource that is becoming expensive and limited. In this context, this thesis develops a global data center-level power and performance optimization approach for Web Server data centers. It presents a power measurement framework for commodity servers, develops empirical models for estimating the power consumed by Web servers, and implements one of the global power optimization heuristics on a state-of-the-art, high-density SeaMicro SM15k cluster by AMD. The power measuring framework is composed of a custom made board, which is able to capture the power consumption; a data acquisition device that samples the measured values; and a piece of software that manages the framework. We show a novel method for developing full system Web server power models that prunes model parameters and reduces non-linear relationships among performance measurements and system power. The Web server power models use as parameters performance indicators read from the machine internal performance counters. We evaluate our approach on an AMD Opteron-based Web server and on an Intel i7-based Web server. Our best model displays an average absolute error of 1.92% for the Intel i7 server and 1.46% for AMD Opteron as compared to actual measurements, and 90th percentile for the absolute percent error equals to 2.66% for Intel i7 and 2.08% for AMD Opteron. We deploy the global power management system in a state-of-the-art SeaMicro SM15k cluster. The implementation relies on the concept of Virtual Power States, a combination of CPU utilization rate to the P/C power states available in modern processors, and on our global optimization algorithm called Slack Recovery. We also propose and implement a novel mechanism to control utilization rates in each server, a key aspect of our power/performance optimization system. Experimental results show that our Slack Recovery-based system can reduce up to 16% of the power consumption when compared to the Linux performance governor and 6.7% when compared to the Linux ondemand governor / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

Orientadores: Edmundo Roberto Mauro Madeira, Luiz Eduardo Buzato / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-21T19:31:37Z (GMT). No. of bitstreams: 1 Nakai_AlanMassaru_D.pdf: 3199160 bytes, checksum: b939ce461412f42df4f371a7cf37d2db (MD5) Previous issue date: 2012 / Resumo: A distribuição de carga é um problema intrínseco a sistemas distribuídos. Esta tese aborda este problema no contexto de servidores web geograficamente distribuídos. A replicação de servidores web em datacenters distribuídos geograficamente provê tolerância a falhas e a possibilidade de fornecer melhores tempos de resposta aos clientes. Uma questão chave em cenários como este é a eficiência da solução de distribuição de carga empregada para dividir a carga do sistema entre as réplicas do servidor. A distribuição de carga permite que os provedores façam melhor uso dos seus recursos, amenizando a necessidade de provisão extra e ajudando a tolerar picos de carga até que o sistema seja ajustado. O objetivo deste trabalho foi estudar e propor novas soluções de distribuição de carga para servidores web geograficamente distribuídos. Para isso, foram implementadas duas ferramentas para apoiar a análise e o desenvolvimento de novas soluções, uma plataforma de testes construída sobre a implementação real de um serviço web e um software de simulação baseado em um modelo realístico de geração de carga para web. As principais contribuições desta tese são as propostas de quatro novas soluções de distribuição de carga que abrangem três diferentes tipos: soluções baseadas em DNS, baseadas em clientes e baseadas em servidores / Abstract: Load balancing is a problem that is intrinsic to distributed systems. In this thesis, we study this problem in the context of geographically distributed web servers. The replication of web servers on geographically distributed datacenters allows the service provider to tolerate failures and to improve the response times perceived by clients. A key issue for achieving good performance in such a deployment is the efficiency of the load balancing solution used to distribute client requests among the replicated servers. The load balancing allows providers to make better use of their resources, soften the need for over-provision, and help tolerate abrupt load peaks until the system can be adjusted. The objective of this work was to study and propose load balancing solutions for geographically distributed web servers. In order to accomplish this objective, we have implemented two tools that support the analysis and development of load balancing solutions, a testbed that was built on top of a real web service implementation and simulation software that is based on a realistic model for web load generation. The main contributions of this thesis are the proposals of four new load balancing solutions that comprehend three types: DNS-based, client-based, and server-based / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

Medasolution is a virtual company designed by the author to handle Medicare insurance business. The web application (which uses ASP.net and SQL Server 2000) facilitates communication between Medasolution and all its clients: members, employers, brokers, and medicare providers through separate web pages based on their category levels. The program incorporates security so that it follows government privacy rules regarding client information.

The purpose of this project is to design, build and implement an instance of a specified online payment system, which is based on micro-payments. The three components for this system are a bookstore, a receipt service and a currency issuer.

Indiana University-Purdue University Indianapolis (IUPUI) / Asynchronous JavaScript and XML (AJAX) is the primary method for enabling asynchronous communication over the Web. Although AJAX is providing warranted real-time capabilities to the Web, it requires unconventional programming methods at the expense of extensive resource usage. WebSockets, which is an emerging protocol, has the potential to address many challenges with implementing asynchronous communication over the Web. There, however, has been no in-depth study that quantitatively compares AJAX and WebSockets. This thesis therefore provides two contributions to Web development. First, it provides an experience report for adding real-time monitoring support over the Web to the Open-source Architecture of Software Instrumentation of Systems(OASIS), which is open-source real-time instrumentation middleware for distributed real-time and embedded (DRE) systems. Secondly, it quantitatively compares using AJAX and WebSockets to stream collected instrumentation data over the Web in real-time. Results from quantitative comparison between WebSockets and AJAX show that a WebSockets server consumes 50% less network bandwidth than an AJAX server; a WebSockets client consumes memory at constant rate, not at an increasing rate; and WebSockets can send up to 215.44% more data samples when consuming the same amount network bandwidth as AJAX.

Indiana University-Purdue University Indianapolis (IUPUI) / Mobile IP though allows mobility features to a node it suffers from signaling Latencies which are mainly incurred due to the fact that the MN itself is involved in the handover process. To overcome this problem proxy mobile IPv6(PMIPv6) was defined where the mobility signaling is taken care of by a proxy server while keeping track of the MN's movement. PMIPv6 has considerably reduced the handover latency but the demand for real time applications over the network has increased tremendously due to recent explosion of the cloud era. My thesis focuses on increasing the L3 handoff signaling efficiency by reducing the latency. This is achieved by our idea to do both the AAA authentication as well as the LMA registration in PMIPv6 at the same time. The simulation results show that our proposed approach perform better than the current PMIPv6 L3 handover signaling reducing the latency as well as packet loss.