Performance Modeling of Proxy Cache Servers

Jelen disszertáció keretében a Proxy Cache szerverek hatékonyságát vizsgáltam meg. A disszertációban bemutattam az általunk általánosított Proxy Cache szerver modellt majd megvizsgáltam, hogy milyen paraméterek mellett éri meg Proxy Cache szervert üzemeltetni. További általánosításként megvizsgáltam azt az esetet is, amikor a Proxy Cache szerver valamint a Web szerver nem megbízható. A dolgozatban tanulmányoztam azt az esetet is, amikor az érkezési folyamatok nem Poisson folyamat, hanem úgynevezett GI - General interarrival" folyamat, melyet az érkezési időközök várható értékével és a relatív szórásnégyzetével jellemzünk, valamint a kiszolgálási idő bármilyen általános eloszlású lehet. Az így kapott modellben a rendszerparaméterek kiszámításához a GI/G/1 approximációt használtam. Végül megvizsgáltam hogyan milyen hatással van a heterogén forgalom a Proxy Cache szerverek hatékonyságára. In this dissertation I described the mathematical model of Proxy Cache servers and I studied the conditions under which installing a Proxy Cache server becomes beneficial. I also analyze how various factors affect the performance of a Proxy Cache server. Than, I generalize the performance model of the Proxy Cache server using a more realistic case when the Proxy Cache server and the remote Web server are unreliable. Later I analyse the case when the arrival process is a general (GI) arrival process characterised by a mean arrival rate and a squared coeficient of variation (SQV) of the inter-arrival time and the service time may have any general distribution. To obtain the response times I used the GI/G/1 approximation. Than I examine the performance behavior of a Proxy Cache server when we use heterogeneous trafic. In this thesis we describe the modified multi-class queuing network model of the Proxy Cache server

Web proxy caching: Understanding and technological assimilation

Los proveedores de acceso a Internet usualmente incluyen el concepto de aceleradores de Internet para reducir el tiempo promedio que tarda un navegador en obtener los archivos solicitados. Para los administradores del sistema es difícil elegir la configuración del servidor proxy caché, ya que es necesario decidir los valores que se deben usar en diferentes variables. En este artículo se presenta la forma como se abordó el proceso de comprensión y asimilación tecnológica del servicio de proxy caché, un servicio de alto impacto organizacional. Además, este artículo es producto del proyecto de investigación “Análisis de configuraciones de servidores proxy caché”, en el cual se estudiaron aspectos relevantes del rendimiento de Squid como servidor proxy cachéInternet Service Providers (ISPs) usually include the concept of internet accelerators to re-duce browser’s response time for obtaining requested files. For system’s administrators is difficult to choose the proxy cache server configuration, considering that it is necessary to decide the values to be used in different variables. this article sets out the way in which the process of understanding and technology assimilation of the proxy cache server was address, which in turn is a high-impact organizational service. Moreover, this article is a product from the research project titled “Configuration Analysis of Proxy Cache Servers”, where relevant aspects of Squid as proxy cache server were studie

Approximation approach to performance evaluation of Proxy Cache Server systems

In this paper we treat a modification of the performance model of Proxy Cache Servers to a more powerful case when the inter-arrival times and the service times are generally distributed. First we describe the original Proxy Cache Server model where the arrival process is a Poisson process and the service times are supposed to be exponentially distributed random variables. Then we calculate the basic performance parameters of the modified performance model using the well known Queueing Network Analysis (QNA) approximation method. The accuracy of the new model is validated by means of a simulation study over an extended range of test cases

A Comprehensive and Cost-Effective Computer Infrastructure for K-12 Schools

Since 1993, NASA Langley Research Center has been developing and implementing a low-cost Internet connection model, including system architecture, training, and support, to provide Internet access for an entire network of computers. This infrastructure allows local area networks which exceed 50 machines per school to independently access the complete functionality of the Internet by connecting to a central site, using state-of-the-art commercial modem technology, through a single standard telephone line. By locating high-cost resources at this central site and sharing these resources and their costs among the school districts throughout a region, a practical, efficient, and affordable infrastructure for providing scale-able Internet connectivity has been developed. As the demand for faster Internet access grows, the model has a simple expansion path that eliminates the need to replace major system components and re-train personnel. Observations of optical Internet usage within an environment, particularly school classrooms, have shown that after an initial period of 'surfing,' the Internet traffic becomes repetitive. By automatically storing requested Internet information on a high-capacity networked disk drive at the local site (network based disk caching), then updating this information only when it changes, well over 80 percent of the Internet traffic that leaves a location can be eliminated by retrieving the information from the local disk cache

Document distribution algorithm for load balancing on an extensible Web server architecture

Access latency and load balancing are the two main issues in the design of clustered Web server architecture for achieving high performance. We propose a novel document distribution algorithm for load balancing on a cluster of distributed Web servers. We group Web pages that are likely to be accessed during a request session into a migrating unit, which is used as the basic unit of document placement. A modified binning algorithm is developed to distribute the migrating units among the Web servers to fulfil the load balancing. We also present a redirection mechanism, which makes use of a migrating unit's property, to reduce the cost of request redirections. The distribution of Web documents would be recomputed periodically to adapt to the changes in client request patterns and system configuration. Simulation results show that our solution can reduce the amount of request redirection and document migration, and it can distribute workload properly among Web servers.published_or_final_versio

OPTIMALISASI PENYIMPANAN VIDEO MENGGUNAKAN VIDEOCACHE PADA PROXY SERVER (Studi Kasus pada Warnet Janturan.Net Yogyakarta)

Peningkatan akses Internet yang tidak selalu bisa dioptimalkan oleh pengguna internet. Masalah-masalah yang timbul sebagai efek dari peningkatan akses Internet antara lain adalah menambah beban web server apalagi kalau sudah menyangkut dengan video streaming pasti berat beban diserver. Padatnya lalu lintas jaringan untuk men-transfer data/berkas, dan lamanya waktu transfer sebagai akibat padatnya lalu lintas jaringan. Salah satu cara untuk mengatasi masalah tersebut adalah menggunakan proxy server videocache.Subjek dalam penelitian ini adalah optimalisasi penyimpanan video menggunakan videocache pada proxy server squid dan videocache sebagai aplikasinya. Penelitian ini menggunakan metode observasi, metode wawancara. Aplikasi yang dibangun adalah proxy server menggunakan aplikasi squid yang mampu membantu meningkatkan kinerja jaringan pada salah satu warnet yang ada di yogyakarta yaitu Janturan.NET. Penyusunan meliputi dengan prosedur diantaranya indentifikasi masalah, analisis kebutuhan, perancangan jaringan, perancangan sistem, serta implementasi jaringan Proxy Server, sedangkan pengujian system dengan black box dan alpha test.Hasil penelitian dapat bekerja dengan optimal pada Optimalisasi Penyimpanan video menggunakan videocache Pada Proxy Server. Sehingga para pelanggan warnet merasa tidak dirugikan. Aplikasi telah diuji menggunakan black box test yang berdasarkan hasil uji coba tersebut dapat disimpulkan bahwa aplikasi ini dapat diterapkan dilokasi penelitian.Kata kunci : Proxy, Server, Squid, Streaming, Cache