Bert J. Dempsey

Who is an open source software developer

Profiling a community of Linux developers.

Design and empirical evaluation of search software for legal professionals on the WWW

Abstract Our research focuses on designing effective search aids for legal researchers interested in law-related information on the world wide web. In this paper we report on the design and evaluation of two software systems developed to explore models for browsing and searching across a user-selected set of WWW sites. A directory services tool, LIBClient, provides a hierarchical index of legal information resources in an interface emphasizing ease-of-use by Internet novices and management of multiple-site searching. To study the relative effectiveness of LIBClient in the hands of legal professionals, nineteen law students were observed using LIBClient and, in separate trials, the popular general-purpose search services to perform known-item searches within a fixed time limit. The experiment indicates the value of LIBClient for focused searching, most properly as a supplement to general-purpose search engines. Motivated by observations from the LIBClient study, a second retrieval experiment explores the effectiveness of a radically different LIBClient design in which the LIBClient interface is combined with a crawler-enhanced search engine, IRISWeb. The LIBClient–IRISWeb system enables full-text searching using natural language queries across a set of WWW pages collected by the IRISWeb crawler. The page harvesting process relies on a cascading set of filters to define the final set of WWW pages to be collected, including user selections in LIBClient, search results from site-specific search engines, and the hyperlink structure at target sites. To evaluate the LIBClient–IRISWeb method, the queries used in the user study are submitted to the system, with excellent retrieval results. In conclusion, our research points to the promise of WWW search tool designs that tightly couple directed browsing with query-based search capabilities using new forms of search automation.

An interactive WWW search engine for user-defined collections

Given the dynamic nature and the quantity of information on the WWW, many individual users and organizations compile and use focused WWW resource lists related to a particular topic or subject domain. The IRISWeb system extends this concept such that any user-defined set of WWW pages (a virtual collection) can be retrieved, indexed, and searched using a powerful full-text search engine with a relevance-feedback interface. This capability adds full-text searching to highly customized subsets of the WWW. Here we describe the IRISWeb software and an experiment that highlights its potential.

Destination buffering for low-bandwidth audio transmissions using redundancy-based error control

Digital audio is becoming increasingly prevalent with the advent of software for Internet telephony and real-time audio playback for World Wide Web browsers. Since audio quality depends on timely delivery of the packet stream, protocol mechanisms must address the control of delays and packet losses in an integrated fashion. Two critical mechanisms for high-quality audio delivery are the receiver buffering strategy and error control. Buffering at the audio receiver is required for continuous playback in the presence of network delay variations (jitter), and a number of algorithms have been proposed. Timely recovery of packet loss protects audio quality against network errors. Recent work has suggested the effectiveness of an approach that sends multiple copies of the audio data in consecutive packets so that small burst losses in the network are overcome. Packet-level traces of Internet audioconferencing software were collected over a network path including LANs and a 28.8 kbits/s dial-up connection. Using these traces in simulations, receiver buffering strategies for controlling packet jitter and for supporting redundancy-based error control are examined. The study determines that jitter control algorithms will not generally provide adequate buffering when the requirements of error control are included. This observation leads to a proposed modification for one popular jitter control algorithm, and the performance trade-offs are explored.

Prospects for the global Internet : new techniques for delivering rich digital collections to users world-wide

Every user of the World Wide Web understands why the WWW is often ridiculed as the World Wide Wait. The WWW and other applications on the Internet have been developed with a client‐server orientation that, in its simplest form, involves a centralized information repository to which users (clients) send requests. This single‐server model suffers from performance problems when clients are too numerous, when clients are physically far away in the Network, when the materials being delivered become very large and hence stress the wide‐area bandwidth, and when the information has a real‐time delivery component as with streaming audio and video materials. Engineering information delivery solutions that break the single‐site model has become an important aspect of next‐generation WWW delivery systems. Intends to help the information professional understand what new directions the delivery infrastructure of the WWW is taking and why these technical changes will impact users around the globe, especially in bandwidth‐poor areas of the Internet.

Internet2 Distributed Storage Infrastructure (I2-DSI) project: improving global access to digital collections

The Internet2 Distributed Storage Infrastructure (I2-DSI) Project (http://dsi.internet2.edu/) [1] is developing a novel distributed network storage solution as part of Internet2 (http://www.internet2.edu) technical activities. Through the replication of application source objects to dedicated replication servers in the network, I2-DSI seeks to reduce the network distance between clients and servers and thereby address the performance challenges facing Internetbased applications. The approach will leverage current capabilities in mass storage and high-bandwidth wide-area networks to enable significant new applications today.

Performance analysis of a scaleable design for replicating file collections in wide-area networks

Mirroring file collections in the global Internet is widely practiced with a recent study estimating the number of WWW hosts with mirrored content at 10% of all WWW hosts. Conventional mirroring tools, however, are not well-suited for the large-scale multiple-site replication services envisioned by projects such as the Internet2 Distributed Storage Infrastructure (I2-DSI) project. This paper presents a scaleable design for the automated synchronization of large collections of files replicated across multiple hosts, as in I2-DSI, and outlines of how the design has been realized using rsync+, a modification to the popular open-source mirroring tool, rsync. A performance study based on an instrumented mirror usingrsync + empirically characterizes server-side processing costs under realistic, large-scale workloads, and supplementary measurements of network throughput across Internet2 links illustrate the achievable network performance in a high-speed wide-area network. These experimental results confirm the validity of scalability arguments for the design, uncover key system parameters for rsync+ that must be tuned for efficient operation, and indicate the limitations of TCP-only transport solutions as the number of mirror sites grows.

Use of an expanding directory interface for WWW legal resources

The Internet contains many legal resources which supplement more established online sources, but effective resource discovery tools are critical for end users [10]. The Directory of Internet-Accessible Legal Resources (DIALeR), http://legalsearch.ils.unc.edu/, was developed to aid in rapid discovery and navigation between high-quality legal sites. The resources in the DIALeR (MS SQL) database were selected by law librarians with an eye towards finding reputable WWW sites that are building significant repositories of public domain documents. The back-end DIALeR interface enables these librarians to easily build, modify, and customize a tree structure of legal topics. The current interface includes portions of the tree that closely follow long-established print indices of the law. For the user, the DIALeR design facilitates the location of document archives, databases, and other topically focused WWW sites via nagivation through a client interface to the underlying database of resources. Constructed from custom COM component software and Active Server Page (ASP) scripts, the DIALeR client interface mimics the wellknown Explorer tool for navigating the file system in MS Windows. Menu items showing a plus-sign (+) can be expanded into sub-items; those with a minus-sign (-) can be contracted; and final items (annotated hyperlinks leading to relevant WWW sites) appear in a separate right-hand frame. While DIALeRs human selection and indexing of resources aids first-order resource discovery, finer-grain searching is achieved through local search tools available at individual sites, e.g., full-text search engines are commonly found at text-rich legal sites.