17602182
Architecture of the artifact-based collaboration system matrix
The UNC Collaboratory project is concerned with both the process of collaboration and with computer systems to support that process. Here, we describe a component of the Artifact-Based Collaboration (ABC) system, called the Matrix, that provides an infrastructure in which existing single-user applications can be incorporated with few, if any, changes and used collaboratively. We take the position that what is needed is not new tools but better infrastructure for using familiar single-user tools collectively. The paper discusses the Matrix architecture, a Virtual Screen component, and generic functions that provide conferencing, hyperlinking, and recording of users' actions for all applications. INTRODUCTION AND MOTIVATION
9694445
The architecture and implementation of a distributed hypermedia storage system
Our project is studying the process by which groups of individuals work together to build large, complex structures of ideas and is developing a distributed hypermedia collaboration environment (called ABC) to support that process. This paper focuses on the architecture and implementation of the Distributed Graph Storage (DGS) component of ABC. The DGS supports a graph-based data model, conservatively extended to meet hypermedia requirements. Some important issues addressed in the system include scale, performance, concurrency semantics, access protection, location independence, and replication (for fault tolerance).
6489448
ABC: a hypermedia system for artifact-based collaboration
Abstract : Our project is studying the process by which groups of individuals work together to build large, complex structures of ideas, and we are developing a distributed hypermedia system to support the process. This description includes a brief overview of the system, but emphasizes three components: a hypermedia data management system or graph server, a set of browsers for working with graph objects, and a set of applications for working with data contents of graph nodes. A number of research issues are raised and discussed in context, including: composite objects; anchored links; scaling up for large applications; partitioning the hypermedia graph; consistency and completeness across subgraphs; and an open, extensible architecture for applications.
18353433
VideoZoom Spatio-Temporal Video Browser
We describe a system for browsing and interactively retrieving video over the Internet at multiple spatial and temporal resolutions. The VideoZoom system enables users to start with coarse, low-resolution views of the sequences and selectively zoom-in in space and time. VideoZoom decomposes the video sequences into a hierarchy of view elements, which are retrieved in a progressive fashion. The client browser incrementally builds the views by retrieving, caching, and assembling the view elements, as needed. By integrating browsing and retrieval into a single progressive retrieval paradigm, VideoZoom provides a new and useful system for accessing video over the Internet. VideoZoom is suitable for digital video libraries and a number of other applications in which streaming methods provide insufficient quality of video, video downloading introduces large latencies, and generating video summaries is difficult or not well integrated with video retrieval tasks.
642671
A secure and reliable bootstrap architecture
In a computer system, the integrity of lower layers is typically treated as axiomatic by higher layers. Under the presumption that the hardware comprising the machine (the lowest layer) is valid, the integrity of a layer can be guaranteed if and only if: (1) the integrity of the lower layers is checked and (2) transitions to higher layers occur only after integrity checks on them are complete. The resulting integrity "chain" inductively guarantees system integrity. When these conditions are not met, as they typically are not in the bootstrapping (initialization) of a computer system, no integrity guarantees can be made, yet these guarantees are increasingly important to diverse applications such as Internet commerce, security systems and "active networks". In this paper, we describe the AEGIS architecture for initializing a computer system. It validates integrity at each layer transition in the bootstrap process. AEGIS also includes a recovery process for integrity check failures, and we show how this results in robust systems.
11571148
Security in Active Networks
The desire for flexible networking services has given rise to the concept of "active networks." Active networks provide a general framework for designing and implementing network-embedded services, typically by means of a programmable network infrastructure. A programmable network infrastructure creates significant new challenges for securing the network infrastructure. 
 
This paper begins with an overview of active networking. It then moves to security issues, beginning with a threat model for active networking, moving through an enumeration of the challenges for system designers, and ending with a survey of approaches for meeting those challenges. The Secure Active Networking Environment (SANE) realizes many of these approaches; an implementation exists and provides acceptable performance for even the most aggressive active networking proposals such as active packets (sometimes called "capsules"). 
 
We close the paper with a discussion of open problems and an attempt to prioritize them.
30871480
Optimized Encodings of Fragments of Type Theory in First-Order Logic
1805433
MPEG-7 MDS Content Description Tools and Applications
In this paper, we present the tools specified by the MDS part of the MPEG-7 standard for describing multimedia data such as images and video. In particular, we focus on the description tools that represent the structure and semantics of multimedia data to whose development we have actively contributed. We also describe some of our research prototype systems dealing with the extraction and application of MPEG-7 structural and semantic descriptions. These systems are AMOS, a video object segmentation and retrieval system, and IMKA, an intelligent multimedia knowledge application using the MediaNet knowledge representation framework.