DOH: A Content Delivery Peer-to-Peer Network

Many SMEs and non-pro¯t organizations su®er when their Web servers become unavailable due to °ash crowd e®ects when their web site becomes popular. One of the solutions to the °ash-crowd problem is to place the web site on a scalable CDN (Content Delivery Network) that replicates the content and distributes the load in order to improve its response time. In this paper, we present our approach to building a scalable Web Hosting environment as a CDN on top of a structured peer-to-peer system of collaborative web-servers integrated to share the load and to improve the overall system performance, scalability, availability and robustness. Unlike clusterbased solutions, it can run on heterogeneous hardware, over geographically dispersed areas. To validate and evaluate our approach, we have developed a system prototype called DOH (DKS Organized Hosting) that is a CDN implemented on top of the DKS (Distributed K-nary Search) structured P2P system with DHT (Distributed Hash table) functionality [9]. The prototype is implemented in Java, using the DKS middleware, the Jetty web-server, and a modi¯ed JavaFTP server. The proposed design of CDN has been evaluated by simulation and by evaluation experiments on the prototype

Информационные технологии в банковской системе

Almost all activities of the Bank subject to the domination systems. The system itself involves a procedure control, a set of interconnected elements, procedures, methods, and many similar concepts. When the Bank is recruiting employees, it applies to this particular system, which involves placing ads on job interviews, the definition of appropriate skills, discussion of working conditions and so on. This process is a slender organized system with its internal procedures and prescribed norms

Bottlenecks and their performance implications in e-commerce systems

Abstract. We present a detailed workload characterization of a multi-tiered system that hosts an e-commerce site. Using the TPC-W workload and via experimental measurements, we illustrate how workload characteristics affect system behavior and operation, focusing on the statistical properties of dynamic page generation. This analysis allows to identify bottlenecks and the system conditions under which there is degradation in performance. Consistent with the literature, we find that the distribution of the dynamic page generation is heavy-tailed, which is caused by the interaction of the database server with the storage system. Furthermore, by examining the queuing behavior at the database server, we present experimental evidence of the existence of statistical correlation in the distribution of dynamic page generation times, especially under high load conditions. We couple this observation with the existence (and switching) of bottlenecks in the system. Keywords: TPC-W, bottleneck identification, workload characterization, query time distribution, autocorrelation.