Performance stress vectors and capacity planning for e-commerce applications

Computing systems are essential resources for both the business and public sectors. With the increasing interdependence of integrated electronic commerce and business applications within the global computing environment, performance and reliability are of great concern. Poor performance can mean lost cooperation, opportunity, and revenue. This paper describes performance challenges that these applications face over the short and long term. We present an analytic technique that can predict the performance of an e-commerce application over a given deployment period. This technique can be used to deduce performance stress testing vectors over this period and for design and capacity planning exercises. A Web-based shopping server case study is used as an example. Published online: 22 August 2001     

Intrusion and intrusion detection

Assurance technologies for computer security have failed to have significant impacts in the marketplace, with the result that most of the computers connected to the internet are vulnerable to attack. This paper looks at the problem of malicious users from both a historical and practical standpoint. It traces the history of intrusion and intrusion detection from the early 1970s to the present day, beginning with a historical overview. The paper describes the two primary intrusion detection techniques, anomaly detection and signature-based misuse detection, in some detail and describes a number of contemporary research and commercial intrusion detection systems. It ends with a brief discussion of the problems associated with evaluating intrusion detection systems and a discussion of the difficulties associated with making further progress in the field. With respect to the latter, it notes that, like many fields, intrusion detection has been based on a combination of intuition and brute-force techniques. We suspect that these have carried the field as far as they can and that further significant progress will depend on the development of an underlying theoretical basis for the field. Published online: 27 July 2001     

A Socio-Technical Approach to Systems Design

This paper examines how the structure of organisations is changing as a result of the global market and new technology and it discusses how these changes are affecting the nature of work. It identifies systems design as a problem-solving activity that requires a multidisciplinary approach, examines the current and new problems of complex systems design and describes how a socio- technical approach which takes account of technical, organisational, economic and social needs can assist the creation of humanistic and effective systems for tomorrow’s world.     

Enhanced abstract data types in object-relational databases

The explosion in complex multimedia content makes it crucial for database systems to support such data efficiently. This paper argues that the “blackbox” ADTs used in current object-relational systems inhibit their performance, thereby limiting their use in emerging applications. Instead, the next generation of object-relational database systems should be based on enhanced abstract data type (E-ADT) technology. An (E-ADT) can expose the semantics of its methods to the database system, thereby permitting advanced query optimizations. Fundamental architectural changes are required to build a database system with E-ADTs; the added functionality should not compromise the modularity of data types and the extensibility of the type system. The implementation issues have been explored through the development of E-ADTs in Predator. Initial performance results demonstrate an order of magnitude in performance improvements. Received January 1, 1998 / Accepted May 27, 1998     

Large scale address recognition systems Truthing,testing, tools,and other evaluation issues

This paper describes the issues involved in the design of a system for evaluating improvements in the performance of a real-time address recognition system being used by the United States Postal Service for processing mail-piece images. Evaluation of the performance of recognition systems is normally carried out by measuring the performance of the system on a representative sample of images. Designing a comprehensive and valid testing scenario is a complex task that requires careful attention. Sampling live mail-stream to generate a deck of images representative of the general mail-stream for testing, truthing (generating reference data on a significant number of images), grading and evaluation, and designing tools to facilitate these functions are important topics that need to be addressed. This paper describes the efforts of the United States Postal Service and CEDAR towards developing an infrastructure for sampling, truthing, and testing of mail-stream images. Received: July 25, 2000 / Revised version: July 31, 2001     

Identity Building in Organisations: Proactive Capability Development

Identity building in organisations is often viewed as legitimacy of value systems of the organisation. Based on empirical studies the task of this article is to argue that such a legitimacy approach risks failing in the longer perspective, if the proactive capability development is neglected. The participatory scenario method presented in this article is one of the possible methods to enhance identity building based on proactive capability development. Correspondence and offprint requests to: Lauge Baungaard Rasmussen, Department of Manufacturing Engineering and Management, Technical University of Denmark, Building 303, 2800 Kgs. Lyngby, Denmark. Tel.: +45 45256025; Fax: +45 45936620; Email: lbr@ipl.dtu.dk     

Cognitive Automation for Tactical Mission Management: Concept and Prototype Evaluation in Flight Simulator Trials

This paper describes an approach to cognitive and cooperative operator assistance in the field of tactical flight mission management. A framework for a generic functional concept is derived from general considerations of human performance and cognitive engineering. A system built according to these human-centred design principles will be able to keep up with the change of situation parameters, in order to provide situational adapted operator assistance. Such a cognitive assistant system represents an approach to ensure the highest degree possible of situation awareness of the flight deck crew as well as a satisfactory workload level. This generic approach to mission management and crew assistance for military aircraft has been realised in different application domains such as military transport and air-to-ground attack. The Crew Assistant Military Aircraft is a functional prototype for the air transport application. Even applications in the domain of uninhabited aerial vehicles (UAV) are in reach. This paper mainly covers one state-of-the-art research and development activity in the domain of combat aircraft: the TMM – Tactical Mission Management System is an experimental solution for the air-to-ground attack role. The TMM has been implemented as a functional prototype in the mission avionics experimental cockpit (MAXC), a development flight simulator at ESG and evaluated with German Air Force pilots as subjects in simulator trials. Therefore, the TMM has been compared with a reference cockpit avionics configuration in terms of task performance, workload, situation awareness and operator acceptance. After giving an overview of the system concepts this paper reports on the experimental design and results of the simulator trial campaign.     

Training Effective Human Performance in the Management of Stressful Emergencies

Emergency situations in industry occur suddenly and often unexpectedly; operators must make critical decisions under stress, and the consequences of errors can be immediate and catastrophic. Training effective performance under stress becomes an important aspect in the management of emergencies. This article proposes a taxonomy of cognitive strategies that enable operators to regulate their thinking and adapt decisions to changes in the demands of the situation. Cognitive strategies, such as, tolerating uncertainty, managing workload, planning for contingencies, and self-monitoring, provide the content of training emergency response. Stress, however, interferes with the learning of strategies, which presents a challenge to the design of training methods. Exposure to stress during training, degree of task decomposition, guidance, contextual variety and feedback are some of the training methods explored to facilitate the acquisition and transfer of cognitive strategies. Diversions from the traditional systems approach to training are pointed out and areas for further training research are identified.     

Negotiating and Understanding Information Systems Requirements: The Use of Set Diagrams

A major contributor to the failure of information technology-based systems is the problem of understanding user or customer requirements in the initial analysis and requirements identification stage of development. This paper identifies and describes an approach to help overcome some of these problems, particularly the mismatch or understanding gap between the customer and the developer. The approach is intended to be used at the early stages of requirement determination and introduces techniques from operational research into the process. In particular set theory and Venn diagrams are used as a way of graphically representing the relationships and gaps in understanding that may exist. The benefit obtained from the use of the technique is partly in the graphical representations themselves but mainly in the dialogue and negotiation that result from the construction of the diagrams. The technique has been developed in a research study of retail organisations’ use of information technology in the UK and an example case study from the sector is used to illustrate and discuss the technique.     

The design of a configurable and reconfigurable middleware platform

Summary. It is now well established that middleware platforms must accommodate an increasingly diverse range of requirements arising from the needs of both applications and underlying systems. Moreover, it is clear that to achieve this accommodation, platforms must be capable of both deployment-time configurability and run-time reconfigurability. This paper describes a middleware platform that addresses these requirements. The platform is built using a well-founded lightweight component model, uses reflective techniques to facilitate (re)configuration, and employs the notion of component frameworks to manage and constrain the scope of reconfiguration operations. Importantly, the platform also aims to achieve high performance and a level of standards conformance (e.g., with CORBA and COM). We demonstrate that, despite its high degree of configurability, the platform performs on a par with standard commercial CORBA ORBs. Received: April 2001 / Accepted: September 2001     

A complete characterization of a family of key exchange protocols

Using a random deal of cards to players and a computationally unlimited eavesdropper, all players wish to share a one-bit secret key which is information-theoretically secure from the eavesdropper. This can be done by a protocol to make several pairs of players share one-bit secret keys so that all these pairs form a tree over players. In this paper we obtain a necessary and sufficient condition on the number of cards for the existence of such a protocol. Published online: 29 January 2002     

Distributed accessibility control points help deliver a directly accessible Web

This paper describes a set of interfaces and mechanisms to enhance access to the World Wide Web for persons with sensory, cognitive, or motor limitations. Paradoxically, although complex Web architectures are often accused of impeding accessibility, their layers expand the range of points where interventions can be staged to improve it. This paper identifies some of these access control points and evaluates the particular strengths and weaknesses of each. In particular, it describes an approach to enhance access that is distributed across multiple control points and implemented as an aggregation of services. Published online: 6 November 2002     

An Evaluation of the Potential of Task Analysis in the Evolution of Interactive Work Systems

Developed forms of task analysis allow designers to focus on both utility and usability issues in the development of interactive work systems. The models they generate represent aspects of the human, computer and domain elements of an interactive work system. Many interactive work systems are embedded in an organisational context. Pressure for changes are present in this context and provide impetus to stakeholders to change work tasks and the supporting tools. Interactive work systems also provide evolutionary pressures of their own, changing the very task they were designed to support. One approach to coping with change has been to evolve interactive work systems. Currently none of these techniques place focus on the performance of tasks as central, and consideration of usability is minimal. However, an evolutionary design approach forces an evolutionary experience upon users, and we cannot be sure whether this approach enhances the user’s experience or degrades their performance. Given the strength of task analysis it is likely that it will be applied within evolutionary contexts. Yet, little work has been undertaken to examine whether its role will, or could be different. We ask how we can move task analysis towards being used in a principled manner in the evolution of interactive work systems. This paper examines a number of features of the approach called task knowledge structures that may be useful in evolving interactive work systems. We look at tasks and their representativeness, roles, goals, objects (their attributes, relationships, typicality and centrality) and actions. We present a developing framework for examining other task analysis approaches for their utility in supporting interactive work systems evolution. Finally, we discuss future work within the area of applying task analysis in the evolution of interactive work systems.     

Building knowledge base management systems

Advanced applications in fields such as CAD, software engineering, real-time process control, corporate repositories and digital libraries require the construction, efficient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up, nor can they be built in terms of existing database technology, because such technology does not support the rich representational structure and inference mechanisms required for knowledge-based systems. This paper proposes a generic architecture for a knowledge base management system intended for such applications. The architecture assumes an object-oriented knowledge representation language with an assertional sublanguage used to express constraints and rules. It also provides for general-purpose deductive inference and special-purpose temporal reasoning. Results reported in the paper address several knowledge base management issues. For storage management, a new method is proposed for generating a logical schema for a given knowledge base. Query processing algorithms are offered for semantic and physical query optimization, along with an enhanced cost model for query cost estimation. On concurrency control, the paper describes a novel concurrency control policy which takes advantage of knowledge base structure and is shown to outperform two-phase locking for highly structured knowledge bases and update-intensive transactions. Finally, algorithms for compilation and efficient processing of constraints and rules during knowledge base operations are described. The paper describes original results, including novel data structures and algorithms, as well as preliminary performance evaluation data. Based on these results, we conclude that knowledge base management systems which can accommodate large knowledge bases are feasible. Edited by Gunter Schlageter and H.-J. Schek. Received May 19, 1994 / Revised May 26, 1995 / Accepted September 18, 1995     

Functionally based virtual embossing

Embossing is the art of decorating metals in relief from the reverse side. This article describes how virtual embossing can be done using a functionally based representation of the metal plate and the tools. The program is implemented as an interactive shape modeler where a functional model of the metal plate is subsequently modified with offset and set-theoretic operations. For visualization, interactive ray tracing is used. Bounding boxes together with the spatial organization of the functional model provide the required fast function evaluation that is usually a bottleneck for functionally based shape modeling systems. The program runs on a personal computer.     

Retina-like visual sensor for fast tracking and navigation robots

This paper describes the development of an anthropomorphic visual sensor which generates a spatially variant resolution image by using a retina-like structure. This sensor consists of a dove prism for image rotation and two linear CCD sensors with 512 pixel/line resolution and holds approximately 45 kbytes of image data. The retina-like sensor has variable resolution with increasing density towards the center of the visual field and yields a polar-coordinate image directly. The motion analysis of the object in the scene from the optical flow is considerably simplified if the velocity is represented in polar coordinates, compared to the case when the image is represented in cartesian coordinates. A calibration procedure for the proposed retina-like sensor is also presented with experimental data to verify the validity of the system. Development of this sensor holds promise in applications to high-speed tracking systems, such as the eyes of navigation robots, because it has data reduction and polar mapping characteristics.     

Evolutionary Algorithms: A Tool for Addressing Problems which Humans Cannot Solve

Although computers have been applied in many areas, there are some applications which seem to be more difficult than others to computerise. Typically these are problems for which we do not have a complete understanding, such as computer vision or robot path planning. Traditional development methods cannot account for a poor analysis of a problem and therefore fail to deliver successful systems for ill-defined problems. Three case studies are presented to demonstrate the application of genetic algorithms and genetic programming to demonstrate how these evolutionary techniques can be applied to ill-defined problems, thus diminishing the need for humans to apply themselves to dangerous or mundane tasks.     

Linguistic Problems with Requirements and Knowledge Elicitation

Human and conversational aspects of requirements and knowledge identification are employed to show that requirements ‘engineering’ is not the same as civil engineering or scientific problem solving. Not only can requirements not be made fully explicit at the start of a project, they cannot be made fully explicit at all. A need is identified to enhance computer-based information systems (CBIS) development methods to accommodate: plurality of incommensurable perspectives, languages and agendas; dynamic representations of system features that can be experienced rather than abstracted and forced into an abstract paper-based representation; recognition that CBIS development is in general a continuous process where users changing their minds is a natural and necessary indication or organisational vitality.  It is suggested that prototyping and rapid application development go some way to addressing these requirements but that they require further development in the light of the theoretical light thrown on the nature of the problem.     

Healthcare Modelling through Role Activity Diagrams for Process-Based Information Systems Development

The aim of this paper is to introduce the socio-technical Role Activity Diagram modelling language to National Health Service (NHS) information systems requirements engineering using a process approach. Most requirements engineering in the NHS is done using data-driven methods such as data flow diagrams. Role Activity Diagrams provide not only a socio-technical method for analysing a particular systems development problem, but they also offer a process-based approach for capturing workflows and their associated information flows, and facilitate communication between analysts and users in an intuitive fashion. In particular, they elicit the important roles in a process and the interaction and collaboration required to achieve the goals of the process. The process approach has been applied in business information systems development. It is introduced here as a potential for systems development in the NHS.