We present ConChord, a large-scale certificate distribution system built on a peer-to-peer distributed hash table. ConChord provides load-balanced storage while eliminating many of the administrative difficulties of traditional, hierarchical server architectures. ConChord is specifically designed

This paper presents two new algorithms that support efficient and complete SDSI name resolution without requiring closure over the set of certificates. This is particularly important for large, distributed certificate sets where calculating the full closure may be prohibitively expensive in terms

Massively multiplayer online games (MMOGs) have become increasingly popular in the recent years, particularly in the form of online role-playing games (MMORPGs). These games support up to several ten thousand players interacting in a virtual game world. The current commercially successful games are client-server based, which is feasible for relatively slow role-playing games. Those have modest bandwidth and latency requirements and are paid for by their customers. For MMOGs with higher realtime requirements and/or a smaller number of customers willing to pay, peer-to-peer networking seems to be a serious alternative. This work analyzes the implementation of both a client-server and a peer-to-peer networking model for the prototype shooter game Planet π4. Initially, a survey introduces recent academic approaches to peer-to-peer systems specifically designed for games. Of those, one system is selected for implementation with Planet π4. Planet π4 is improved in several aspects for the purpose of analyzing various network implementations. First, its architecture is restructured and cleaned to allow for an easy replacement of the networking component. Second, its core is modified to work in a completely event-based mode, supporting the execution of the game in an discrete-event-based network simulator. Third, a simple artificial intelligence player is developed for workload generation in large (and possibly simulated) networks. Furthermore, the newly developed transport protocol CUSP is applied for the network implementation, thus the game is the first real application using CUSP. Finally the game Planet π4 is integrated with the CUSP network simulator, allowing to run the whole game in a simulated network without the need for modification of its core components. Kurzfassung Massen-Mehrspieler-Onlinespiele (Massively multiplayer online games; MMOGs) wurden in den vergangenen Jahren zunehmend populär, insbesondere in Form von Online-Rollenspielen (MMORPGs). In

Abstract: Online learning initia-tives over the past decade have become increasingly comprehen-sive in their selection of courses and sophisticated in their presen-tation, culminating in the recent announcement of a number of consortium and startup activities that promise to make a university education on the internet, free of charge, a real possibility. At this pivotal moment it is appropriate to explore the potential for obtaining comprehensive bioinformatics training with currently existing free video resources. This article pre-sents such a bioinformatics curric-ulum in the form of a virtual course catalog, together with editorial commentary, and an assessment of strengths, weaknesses, and likely future directions for open online learning in this field. Online Learning Comes of Age Online academic ‘‘courseware’ ’ at the university level has now been available to the public for a decade, the earliest concerted effort having originated in 2002 with the Massachusetts Institute of Technology (MIT) and their OpenCour-seWare initiative