Peter J. Nürnberg

Addressing Interoperability in Open Hypermedia: the Design of the Open Hypermedia Protocol

Abstract Early hypertext systems were monolithic and closed, but newer systems tend to be open, distributed, and support collaboration. While this development has resulted in increased openness and flexibility, integration or adaptation of various different tools (such as content editors, viewers, services, or even other link servers) has remained a tedious task. Many developers were implementing essentially similar components, simply for the benefit of having their own platform on which to experiment with hypertexts. The open hypermedia community is addressing this issue of interoperability between open hypermedia systems. The goal of this effort is to provide an open framework that can be used by application developers outside the community to construct more powerful hypermedia-aware applications. The design and evolution of this framework is presented along with the requirements that drove its development. The framework has matured to the point where it has supported the creation of a number of researc...

Multiple open services: a new approach to service provision in open hypermedia systems

Over the past decade, hypermedia systems have become increasingly open, distributed, and modular. As a direct result of this, open hypermedia systems have been increasingly successful in providing middleware services such as linking to a large set of clients. This paper presents a new approach to service provision in open hypermedia systems based on the concept of multiple open services. The overall idea with multiple open services is to rethink the way in which services are provided to clients. The goal is to split up services into components, each of which provides a general, scalable, and functionally independent (orthogonal) service. This results in a highly flexible architectural framework that can serve as a vehicle to further investigate many of the open issues relating to open hypermedia systems. The approach can be viewed as a natural next step in the evolution towards more open, distributed, and modular hypermedia systems. The concept of multiple open services is described in detail, and a proof of concept implementation called Construct is presented.

CAOS: a collaborative and open spatial structure service component with incremental spatial parsing

This paper introduces a project that provides spatial hypermedia services as part of a component-based open hypermedia system (CB-OHS). We focus on the issues of storing both the information space and the parsed spatial structure (for structure sharing purposes) and collaboration support. Continuous re-parsing of spatial structure guarantees consistency between spatial and parsed structure. This promotes parsed structure to first-class status, making persistent storage of it attractive; and, it ensures a consistent view of the parsed structure between collaborative users. For efficiency reasons, the spatial parser is incremental. An accompanying spatial editor shows the validity and utility of the approach.

Evolving hypermedia middleware services: lessons and observations

In this paper, we consider the evolution of hypermedia system architectures from the monolithic systems of the 1980’s to the middleware-oriented component-based open systems of today. We look at the various problems that users and system designers encountered with systems at various stages of this development, focusing particularly on problems that were solved or caused by moving toward a more middleware-oriented approach. Although we cast our discussion in terms of specific hypermedia systems, we believe that many of our observations on the advantages and challenges of our current middleware approach may be helpful to those in other areas of system research.

Interoperability between hypermedia systems: the standardisation work of the OHSWG

CONTENTS OF THE TECHNICAL BRIEFING The Open Hypermedia Systems Working Group (OHSWG) was formed at the second workshop on open hypermedia systems (OHS), held in April, 1996, in Washington, DC, in conjunction with the 1996 ACM Conference on Hypertext. The original purpose of defining an open hypermedia protocol for OHS clients has evolved into an effort to standardise general hypermedia systems work. This broader effort is driven by the desire to maximise the applicability of the last decade of hypermedia systems and infrastructure research.

A development environment for building component-based open hypermedia systems

The Construct development environment is targeted at the construction of different types of hypermedia services. The primary goal of the environment is to ease the construction of component-based open hypermedia systems by providing development tools that assist the system developers in the generation of the set of services that make up a hypermedia system.

What was the question? Reconciling open hypermedia and World Wide Web research

This paper considers some of the issues surrounding the relationship between open hypermedia systems research and World Wide Web research. Both areas claim to address advanced hypermedia systems issues, but do so in quite different ways. Although there has been some cooperation between members of these fields, there is significant room for improvement. With both fields using much different approaches in what is ostensibly the same area, researchers often feel more need to justify their approach over others instead of looking for ways to synthesize their results. In this paper, we consider two “extremist” positions that caricature/characterize points of view held by some members of these fields, allowing each field to “make its case” as the “true” home of hypermedia systems research. We then reconcile these radically different perspectives, and in doing so, propose a framework that makes more apparent the contributions of each field and that we feel forms a basis for more fruitful cooperation.

Structuring Facilities in Digital Libraries

Digital libraries offer much promise for patrons and many challenges for system designers and implementers. One important issue that faces digital library system designers is the type of support provided to patrons for intellectual work. Although many researchers have noted the desirability of robust hypermedia structuring facilities in digital library systems, this research has tended to focus on navigational hypermedia (primarily used for associative storage and retrieval) only. Many other types of hypermedia, such as spatial, issue-based, and taxonomic, have been ignored. We briefly review some of our experiences with building digital library systems and discuss some of the lessons we learned from our initial prototypes. We then present a scenario of digital library work that illustrates many of the kinds of tasks we have observed users of our systems perform. We use this scenario to suggest a potential area of improvement for current hypermedia support in digital library systems and discuss some of our initial work in this area. Finally, we present some directions of future work and some concluding remarks.

A Grand Unified Theory for Structural Computing

Structural computing, in one sense, seeks to unify the notions of data and structure under a synthesized abstraction, by which data and structure become views to be applied as the need or desire arises. Indeed, one way of looking at structural computing is that the notions of data and structure are contextual, not essential. Any entity may be data to one person (application, agent, whatever) at one moment, and structure to another. Data and structure are matters of interpretation, not essence. What exactly this has bought us is discussed at length elsewhere [7,10,11].

A Component-Based Open Hypermedia Approach to Integrating Structure Services

Abstract In this paper, we consider the issue of integrating different structure services within a component-based open hypermedia system. We do so by considering the task of collaborative editing, which calls for a variety of different structures traditionally supplied by different structure services. We discuss the nature of collaborative editing and how it can be supported by a combination of spatial and navigational hypermedia services. We then present a component-based open hypermedia system architecture and describe various methods of integrating different structure services provided within such an architecture. We show the advantages of integration within a component-based framework over other means of integration, highlighting some of the main advantages of the component-based approach to open hypermedia system design and implementation.