Multimedia network protocols: where are we?

Protocols for multimedia communication are needed to integrate into a single network services intended to satisfy the different requirements of multiple types of traffic. An essential prerequisite for designing these protocols is that the services to be offered by the network must be selected and specified in detail. We present the service models proposed, or being developed, by the Internet community, by the ATM community, and by the Tenet Group. We compare their common characteristics, which reveal the characteristics of the first integrated services networks are likely to offer. The services referred to in this paper are those at the network and transport layers, which support the services to be offered to the system's end users.     

Group and Individual Time Management Tools: What You Get is Not What You Need

Some studies of diaries and scheduling systems have considered how individuals use diaries with a view to proposing requirements for computerised time management tools. Others have focused on the criteria for success of group scheduling systems. Few have paid attention to how people use a battery of tools as an ensemble. This interview study reports how users exploit paper, personal digital assistants (PDAs) and a group scheduling system for their time management. As with earlier studies, we find many shortcomings of different technologies, but studying the ensemble rather than individual tools points towards a different conclusion: rather than aiming towards producing electronic time management tools that replace existing paper-based tools, we should be aiming to understand the relative strengths and weaknesses of each technology and look towards more seamless integration between tools. In particular, the requirements for scheduling and those for more responsive, fluid time management conflict in ways that demand different kinds of support.     

Discovery and Integration of Mobile Communications in Everyday Life

We report on the results of a study in which 19 new mobile telephone users were closely tracked for the first six weeks after service acquisition. Results show that novices tend to rapidly modify their perceptions of social appropriateness around mobile phone use, that actual nature of use frequently differs from initial predictions, and that comprehension of service-based technologies can be problematic. We also describe instances and features of mobile telephony practice. When in use, mobile phones occupy multiple social spaces simultaneously, spaces with norms that sometimes conflict: the physical space of the mobile phone user and the virtual space of the conversation.     

Workflow Requirements Modelling Using XML

When modelling inter-organisational workflow it is important not to make assumptions such as with regard to the formats of the data exchanged between the workflow participants or the technical infrastructures and platforms, as they can restrict the range of possible workflow management implementations. The approach presented in this paper allows for the conceptual modelling of workflow processes using primitive constructs such as nodes, rules and business documents. The paper presents both a graphical notation for modelling workflows as well as a mapping of the workflow constructs to XML models that follows the Workflow Management Coalition interoperability standards. This allows the modelled workflow to be interpreted and executed by a variety of workflow engines.     

Context-aware Retrieval: Exploring a New Environment for Information Retrieval and Information Filtering

The opportunities for context-aware computing are fast expanding. Computing systems can be made aware of their environment by monitoring attributes such as their current location, the current time, the weather, or nearby equipment and users. Context-aware computing often involves retrieval of information: it introduces a new aspect to technologies for information delivery; currently these technologies are based mainly on contemporary approaches to information retrieval and information filtering. In this paper, we consider how the closely related, but distinct, topics of information retrieval and information filtering relate to context-aware retrieval. Our thesis is that context-aware retrieval is as yet a sparsely researched and sparsely understood area, and we aim in this paper to make a start towards remedying this.     

Handling message semantics with Generic Broadcast protocols

Summary. Message ordering is a fundamental abstraction in distributed systems. However, ordering guarantees are usually purely “syntactic,” that is, message “semantics” is not taken into consideration despite the fact that in several cases semantic information about messages could be exploited to avoid ordering messages unnecessarily. In this paper we define the Generic Broadcast problem, which orders messages only if needed, based on the semantics of the messages. The semantic information about messages is introduced by conflict relations. We show that Reliable Broadcast and Atomic Broadcast are special instances of Generic Broadcast. The paper also presents two algorithms that solve Generic Broadcast. Received: August 2000 / Accepted: August 2001     

Universal Access in the Information Society: Methods, Tools, and Interaction Technologies

Accessibility and high quality of interaction with products, applications, and services by anyone, anywhere, and at any time are fundamental requirements for universal access in the emerging Information Society. This paper discusses these requirements, and their relation to the concept of automated adaptation of user interfaces. An example application is presented, showing how adaptation can be used to accommodate the requirements of different user categories and contexts of use. This application is then used as a vehicle for discussing a new engineering paradigm appropriate for the development of adaptation-based user interfaces. Finally, the paper investigates issues concerning the interaction technologies required for universal access. Published online: 23 May 2001     

Configuring the Mobile User: Sociological and Industry Views

This article considers the role of the consumer in the diffusion of mobile telecommunications technologies. There is presently little research on the consumption and use of mobile technologies, and the aim of the present paper is to facilitate discussion about the way consumer behaviour is currently understood in industry and academia. The paper considers key themes in social science research on mobile ICTs, and understandings of the consumer held by those in the mobile industry. Bringing these understandings together, we reiterate the now well attested view that the diffusion and consumption of mobile telephony and computing cannot be understood without investigating the contexts and processes of their use in everyday life.     

Program model checking as a new trend

This paper introduces a special section of the STTT journal containing a selection of papers that were presented at the 7th international SPIN workshop, Stanford, 30 August – 1 September 2000. The workshop was named SPIN Model Checking and Software Verification, with an emphasis on model checking of programs. The paper outlines the motivation for stressing software verification, rather than only design and model verification, by presenting the work done in the Automated Software Engineering group at NASA Ames Research Center within the last 5 years. This includes work in software model checking, testing like technologies and static analysis. Published online: 2 October 2002     

Formal verification of conflict detection algorithms

Safety assessment of new air traffic management systems is a main issue for civil aviation authorities. Standard techniques such as testing and simulation have serious limitations in new systems that are significantly more autonomous than the older ones. In this paper, we present an innovative approach for establishing the correctness of conflict detection systems. Fundamental to our approach is the concept of trajectory, and how we represent a continuous physical trajectory by a continuous path in the x-y plane constrained by physical laws and operational requirements. From the model of trajectories, we extract, and formally prove, high-level properties that can serve as a framework to analyze conflict scenarios. We use the AILS (Airborne Information for Lateral Spacing) alerting algorithm as a case study of our approach. Published online: 19 November 2002     

When are Personal Technologies for Children?

This paper will discuss the various issues surrounding personal technologies for children. Three critical questions will be discussed: Why can technology be important for children? What activities can technology support? And what changes should be considered for the future?     

An architecture to support scalable online personalization on the Web

Online personalization is of great interest to e-companies. Virtually all personalization technologies are based on the idea of storing as much historical customer session data as possible, and then querying the data store as customers navigate through a web site. The holy grail of online personalization is an environment where fine-grained, detailed historical session data can be queried based on current online navigation patterns for use in formulating real-time responses. Unfortunately, as more consumers become e-shoppers, the user load and the amount of historical data continue to increase, causing scalability-related problems for almost all current personalization technologies. This paper chronicles the development of a real-time interaction management system through the integration of historical data and online visitation patterns of e-commerce site visitors. It describes the scientific underpinnings of the system as well as its architecture. Experimental evaluation of the system shows that the caching and storage techniques built into the system deliver performance that is orders of magnitude better than those derived from off-the-shelf database components. Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001     

Active rules for XML: A new paradigm for E-services

XML is rapidly becoming one of the most widely adopted technologies for information exchange and representation. As the use of XML becomes more widespread, we foresee the development of active XML rules, i.e., rules explicitly designed for the management of XML information. In particular, we argue that active rules for XML offer a natural paradigm for the rapid development of innovative e-services. In the paper, we show how active rules can be specified in the context of XSLT, a pattern-based language for publishing XML documents (promoted by the W3C) which is receiving strong commercial support, and Lorel, a query language for XML documents that is quite popular in the research world. We demonstrate, through simple examples of active rules for XSLT and Lorel, that active rules can be effective for the implementation of e-commerce services. We also discuss the various issues that need to be considered in adapting the notion of relational triggers to the XML context. Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001     

Dialoguing with developers and suppliers of adaptive computer technologies: Data and recommendations

The authors report on findings on computer technology needs and concerns of 725 Canadian college and university students with a wide range of disabilities. The vast majority of this sample population uses computers and almost half need an adaptation to use computers effectively. The authors provide information about computer technologies used by students with different disabilities, describe adaptations/adaptive computer technologies that students find useful, report issues faced by users and non-users of computers in postsecondary education, and discuss reasons why students are not using needed adaptations/adaptive technology. Based on these findings, the authors provide recommendations for adaptive computer hardware and software developers and vendors. Published online: 21 March 2002     

Organisational Appropriation of Technology: A Case Study

This paper investigates how organisations – as joint cognitive systems – deal with change. This is explored in a case study into the use of web-based technology in an organisation and the ways in which its current and future use may be influenced by the local concerns of the actors with it. The paper looks at some of the factors that need to be taken into account for improving technology, and more specifically, in intranet development. In particular, the paper discusses the case experience in the light of previous research in IT-enabled organisational transformation and contributes to our understanding of human interaction with network technologies in an organisational context.     

Embodiments, avatars, clones and agents for multi-user, multi-sensory virtual worlds

This paper explores the issue of user embodiment within collaborative virtual environments. By user embodiment we mean the provision of users with appropriate body images so as to represent them to others and also to themselves. By collaborative virtual environments we mean multi-user virtual reality systems which explicitly support cooperative work (although we argue that the results of our exploration may also be applied to other kinds of collaborative system). The main part of the paper identifies a list of embodiment design issues grouped by the general themes of personal representation, conveying activity, embodiment in heterogeneous systems, embodiment of agents, and ethical issues. These issues are illustrated with examples from our own DIVE and MASSIVE collaborative virtual environments. The paper also uses this set of issues as an analytical framework for comparing a number of other communication technologies.     

The Mobile Phone: An Identity on the Move

This paper analyses the shifting identity of the mobile phone in the light of research carried out in 1996 on a representative population sample from five major European countries: Italy, UK, France, Germany and Spain. A total of 6609 people were interviewed by means of a telephone survey. The mobile phone emerged as a charismatic technology compared to other mobile technologies (laptop and car phone) and as a leading technology that, in just a few years, has appropriated 11% of total telephone traffic. It has “dragged” its widespread presence and amount of use from the workplace to the domestic sphere, although in Italy, where it has had greatest success, its widespread use has been detached from its use in the workplace. Another emerging result is that the use of the mobile phone is not correlated to strong residential mobility in individuals.     

Optic flow estimation by a Hopfield neural network using geometrical constraints

Sparse optic flow maps are general enough to obtain useful information about camera motion. Usually, correspondences among features over an image sequence are estimated by radiometric similarity. When the camera moves under known conditions, global geometrical constraints can be introduced in order to obtain a more robust estimation of the optic flow. In this paper, a method is proposed for the computation of a robust sparse optic flow (OF) which integrates the geometrical constraints induced by camera motion to verify the correspondences obtained by radiometric-similarity-based techniques. A raw OF map is estimated by matching features by correlation. The verification of the resulting correspondences is formulated as an optimization problem that is implemented on a Hopfield neural network (HNN). Additional constraints imposed in the energy function permit us to achieve a subpixel accuracy in the image locations of matched features. Convergence of the HNN is reached in a small enough number of iterations to make the proposed method suitable for real-time processing. It is shown that the proposed method is also suitable for identifying independently moving objects in front of a moving vehicle. Received: 26 December 1995 / Accepted: 20 February 1997     

Role of a Common Frame of Reference in Cognitive Cooperation: Sharing Tasks between Agents in Air Traffic Control

This study deals with cognitive cooperation in the context of the design of cooperative computer support for sharing aircraft conflict detection and resolution tasks between human and machine in air traffic control. In order to specify some necessary cooperative capabilities of such a system, we have observed an artificial situation on a simulator where two radar controllers (RCs) had to cooperate for the management of a heavy traffic within a single sector. This paper reports the analysis of the verbal communications between the two RCs recorded during the simulation. The results enabled us to describe the elements of a common frame of reference (COFOR), elaborated and updated by the two RCs, as a crucial cooperative activity in this kind of situation. They also show the role of this COFOR in the implicit detection and resolution of interference between the RCs’ individual activities. Their contribution to design, associated with other investigations and the state of the art, is discussed.