John J. Leggett

Digital libraries

ing Education-support Object-oriented Accessibility Electronic publishing OCR Agents Ethnographic study OODB support Annotation Filtering Personalization Archive Geographic information system Preservation Billing, charging Hypermedia Privacy Browsing Hypertext Publisher library Catalog Image processing Repository Classification Indexing Scalability Clustering Information retrieval Searching Commercial service Intellectual property rights Security Content conversion Interactive Sociological study Copyright clearance Knowledge base Storage Courseware Knowbot Standard Database Library science Subscription Diagrams (e.g., CAD) Mediator Sustainability Digital video Multilingual Training support Discipline-level library Multimedia stream playback Usability Distributed processing Multimedia systems Virtual (integration) Document analysis Multimodal Visualization Document model National library World-Wide Web Economic study Navigation its characterization of digital libraries. Many important projects and perspectives have been omitted. Here we give some pointers to aid further exploration, and of course we encourage interested readers to attend the numerous conferences and workshops scheduled in this field, many sponsored by or in cooperation with ACM and its SIGs. One early journal special issue is introduced in [6]. It includes articles on copyright and intellectual property rights, a subscription model for handling funds transfer related to digital libraries, a description of the evolution of the WAIS search system in general and its interfaces in particular, an overview of the Right Pages system and its use of OCR and document analysis algorithms, and an early overview of the Envision system [7]. We note that to many, intellectual property rights issues and ways to obtain revenue streams to sustain digital libraries are the most important open problems. The largest digital library conference makes its proceedings available over the WWW [9]. These contain many insightful discussions, proposals of new research ideas, descriptions of base technologies, and explanations of how the broad concept of a digital library fits in with the needs of specific user communities and the information they require. Readers can find a variety of works on agents, architectures, catalogs, collaboration, compression, document analysis from OCR and page images, document structure, electronic journals, heterogeneous sources, knowledge-based approaches, library science, numerical data collections, object stores, and organizational usability. For more details on the origins of the Digital Library Initiative, and for a variety of perspectives on open research problems, we refer the reader to [5]. This work also has numerous pointers to people, projects, institutions, and other reference works in the area. For a perspective on the role the computer industry should have in this field, see [10]. This report outlines IBM’s perspective on key supporting technologies and on the unique challenges highlighted by the emergence of digital libraries. We expect considerable interest from the corporate sector as well as from government agencies in this important area of information technology. For lack of space, we have had to omit many publications on networking and storage technologies, sociological and ethnographic studies, library and information science, OCR and document analysis or conversion, and rights management. These and other works are needed to round out the discussion of digital libraries. However, we encourage you to read the rest of this issue as a good starting point for your future studies of this important field. We invite you to not only use but also help in the creation of a future World Digital Library System!

Dynamic identity verification via keystroke characteristics

The implementation of safeguards for computer security is based on the ability to verify the identity of authorized computer systems users accurately. The most common form of identity verification in use today is the password, but passwords have many poor traits as an access control mechanism. To overcome the many disadvantages of simple password protection, we are proposing the use of the physiological characteristics of keyboard input as a method for verifying user identity. After an overview of the problem and summary of previous efforts, a research study is described which was conducted to determine the possibility of using keystroke characteristics as a means of dynamic identity verification. Unlike static identity verification systems in use today, a verifier based on dynamic keystroke characteristics allows continuous identity verification in real-time throughout the work session. Study results indicate significant promise in the temporal personnel identification problem.

Verifying identity via keystroke characteristics

Abstract This paper reports on an experiment that was conducted to assess the viability of using keystroke digraph latencies (time between two successive keystrokes) as an identity verifier. Basic data are presented and discussed that characterize the class of keystroke digraph latencies that are found to have good potential as static identity verifiers as well as dynamic identity verifiers. Keystroke digraph latencies would be used in conjunction with other security measures to provide a total security package.

As we should have thought

The hypermedia field has long realized the need for firstclass structural abstractions. However, we have failed to generalize the concept of ubiquitous structure management to problem domains other than navigation of information spaces. In this paper, we argue for the recognition of such a generalization, called structural computing, in which we assert the primacy of structure over data. We provide examples of four problem domains that are more naturally modeled with structure than data. We argue that support for structural computing must come in the form of new models, operating systems, and programming languages. We also assert that the experience gained by hypermedia researchers over the last decade may be naturally extended to form the basis of the new field of structural computing, and furthermore, the broadening of the applicability of our work is necessary for the continued vitality of our research community.

Hyperform: using extensibility to develop dynamic, open, and distributed hypertext systems

An approach to flexible hyperbase (hypertext database) support predicated on the notion of extensibility is presented. The extensible hypertext platform (Hyperform) implements basic hyperbase services that can be tailored to provide specialized hyperbase support. Hyperform is based on an internal computational engine that provides an objectoriented extension language which allows new data model objects and operations to be added at runtime. Hyperform has a number of built-in classes to provide basic hyperbase features such as concurrency control, notification control (events), access control, version control and search and query. Each of these classes can be specialized using multiple inheritance to form virtually any type of hyperbase support needed in next generation hypertext systems. This approach greatly reduces the effort required to provide high quality customized hyperbase support for distributed hypertext applications. Hyperform is implemented and operational in Unix environments. This paper describes the Hyperform approach, discusses its advantages and disadvantages, and gives examples of simulating the HAM and the Danish HyperBase in Hyperform. Hyperform is compared with related work from the HAM generation of hyperbase systems and the current status of the project is reviewed.

The HyperDisco approach to open hypermedia systems

Computing support for large engineering enterprises provides an example of the need for hypermedia-based collaborative computing systems composed of a large number of distributed heterogeneous tools. These computing environments place complex requirements on the underlying hypermedia platform. To support integration of independently written tools for these environments, hypermedia platforms must address several important issues such as scalability, openness, distribution, heterogeneity, interoperability, extensibility and computation. This paper describes the HyperDisco approach to open hypermedia systems. HyperDisco provides an extensible object-oriented hypermedia platform supporting intertool linking, computation, concurrency control, noti cation control, version control, access control, query and search, and various other features. The present work has two main objectives: 1) to provide a platform to integrate existing and future distributed heterogeneous tools and data formats and 2) to provide a platform to extend integrated tools to handle multiple collaborating users and multiple versions of shared artifacts. The paper presents important dimensions of hypermedia platforms that helped to formulate the goals for HyperDisco, the HyperDisco prototype, and two integration examples to illustrate the distinctive features of the HyperDisco approach.

Hypermedia operating systems: a new paradigm for computing

Hypermedia is often viewed as either a paradigm for human-computer interaction or information organization. Human-computer interaction provides a view of hypermedia that involves the creation, manipulation, and access of information through a “point-and-click” navigation mechanism. Information organization provides a view of hypermedia that involves the storage of information as a set of data and metadata objects, where metadata objects capture structural relationships among information objects. This paper describes a third view of hypermedia — hypermedia as a computing paradigm. In this paper, we explore the implications of pushing hypermedia beyond its traditional role in human-computer interaction and information organization into the computer’s core operating environment. We believe the resulting hypermedia operating systems provide a new paradigm for computing — one in which human-computer interaction, information storage and retrieval, programming, and control are integrated in a common conceptual framework. We discuss the basic concepts of hypermedia operating systems and describe a general hypermedia operating system architecture and prototype. While this work represents only a beginning, we feel that viewing hypermedia as a computing paradigm offers a broad new field of research.

Semantic data modeling of hypermedia associations

Many important issues in the design and implementation of hypermedia system functionality focus on the way interobject connections are represented, manipulated, and stored. A prototypic system called HB1 is being designed to meet the storage needs of next-generation hypermedia system architectures. HB1 is referred to as a hyperbase management system (HBMS) because it supports, not only the storage and manipulation of information, but the storage and manipulation of the connectivity data that link information together to form hypermedia. Among HB1s distinctions is its use of a semantic network database system to manage physical storage. Here, basic semantic modeling concepts as they apply to hypermedia systems are reviewed, and experiences using a semantic database system in HB1 are discussed. Semantic data models attempt to provide more powerful mechanisms for structuring objects than are provided by traditional approaches. In HB1, it was necessary to abstract interobject connectivity, behaviors, and information for hypermedia. Building on top of a semantic database system facilitated such a separation and made the structural aspects of hypermedia conveniently accessible to manipulation. This becomes particularly important in the implementation of structure-related operations such as structural queries. Our experience suggests that an integrated semantic object-oriented database paradigm appears to be superior to purely relational, semantic, or object-oriented methodologies for representing the structurally complex interrelationships that arise in hypermedia.

Workspaces: the HyperDisco approach to Internet distribution

Hypermedia concepts are currently being deployed in a variety of information systems such as the World Wide Web, software development environments, large engineering enterprises, collaborative authoring systems, and digital library systems. The complex requirements of these application areas have resulted in extensive research into hypermedia infrastructures. The HyperDisco project is about design, development, deployment and assessment of hypermedia infrastructures. Previous HyperDisco experiments have dealt with integration of a small set of tools supporting authoring and extension of the integrated tools to support multiple collaborating users and multiple versions of shared files. These experiments were conducted on a local area network using a single centralized workspace. The latest version of HyperDisco supports collaboration and versioning over multiple workspaces distributed across the Internet. This paper gives a brief overview of HyperDisco, describes the workspace concept and reports on the latest experiments: (1) an experiment that allows the use of multiple workspaces on a local area network, (2) an experiment that allows workspaces to be distributed across the Internet, and (3) an experiment focusing on hypermedia modeling and presentation issues of distributed workspaces.

PROXHY: a process-oriented extensible hypertext architecture

This research describes a new architecture for hypertext environments. The architecture merges the process, object-oriented, and hypertext models to provide hypertext services to object-based, distributed, application components. Through this architecture, applications are integrated to form a comprehensive hypertext computing environment, allowing links to connect applications or objects in different applications. The architecture separates hypertext and application functionality so that multiple applications can use the facilities of a common hypertext layer. The design of the architecture is such that components can be extended or tailored in order to support future applications, multimedia objects, or the needs of specific applications or users. The process-based, object-oriented framework allows objects of arbitrary complexity to live and interact in a hypertext world. Additionally, the protocol and facilities which support component interaction provide location transparency, arbitrary object granularity, and parallel computation over a network. This dissertation provides a conceptual model of hypertext and a general architecture for hypertext system construction. Related literature from object-oriented programming, operating systems, multimedia applications, and database is discussed in terms of the architecture. A hypertext data model, computational model, and hypertext system taxonomy are used to discuss the capabilities of current hypertext systems. Interaction scenarios are provided in order to illustrate object interaction and the distribution of work among the components of the architecture. A prototype system, implemented to demonstrate the feasibility of the architecture, is discussed. The prototype illustrates all aspects of the architecture including distributed application and hypertext components, cross-application linking, and anchors acting as proxy objects for applications. Application scenarios, problems and limitations, and future research issues provide an understanding of the power of the architecture and its potential for impacting the design of next-generation hypertext systems.