Thiruvengadam Radhakrishnan

Optimal checkpointing and local recording for domino-free rollback recovery

Abstract Backward error recovery or rollback recovery is a well-known technique used in the design of reliable uni-processor computer systems. However, use of this technique for design of reliable distributed computer systems could result in uncontrolled rollback which is known as the domino effect. Here, we formally present the reasons for the domino effect by specifically identifying the unmatched receives (backward dependency) and unmatched sends (retransmission dependency) that occur during reexecution as the sole causes. A technique is developed which selectively stores the received messages in order to account for the backward dependencies and which coordinates the checkpoints to eliminate the retransmission dependencies, thus achieving domino-free rollback. Rollback is confined only to the interacting processes by dependency tracking of the messages. Further, we present a scheme for identifying and purging possibly contaminated messages during recovery. Our scheme is compared with some of the existing schemes and its significant advantages are highlighted.

Lotka's Law and Computer Science Literature

An experiment to verify the satisfaction of Lotkas law, with the papers published in the area of computer science, is reported. It is seen that the estimates of this law deviate considerably from the observations. Need for further experiments to verify Lotkas law in the area of applied sciences and engineering is emphasized.

Beyond power: making bioinformatics tools user-centered

User-centered design techniques can broaden the appeal, use, and effectiveness of Web-based bioinformatics tools.

On eliciting requirements from end-users in the ICT4D domain

Currently, there is much interest in harnessing the potential of new and affordable Information and Communication Technologies (ICT) such as mobile phones, to assist in reducing disparities in socioeconomic conditions throughout the world. Such efforts have come to be known as ICT for Development or ICT4D. Although this field of research holds much promise, few projects have managed to achieve long-term sustained success. Among the many reasons for this, from a software engineering perspective, in many cases, it can be attributed to inadequacies in gathering and defining software requirements. Incomplete software requirements and the consequent failures in creating sustainable systems arise because of inadequate consideration of the high-level social development goals, neglect of environmental constraints and/or a lack of adequate input from end-users regarding their specific needs and socio-cultural context. We propose enhancements to the requirements elicitation methodology specifically adapted to address these shortcomings. Our approach incorporates the novel technique of Structured Digital Storytelling to elicit input from end-users who have limited literacy and applies a conceptual model derived from Communications Theory to analyse the constraints that arise from their socio-cultural context. The needs, goals and constraints thus identified are integrated using a goal-based analysis to produce a more informed understanding of the potential areas of technology intervention and the needed software requirements. We illustrate our approach and validate its effectiveness with a field study.

Validating dynamic properties of rule-based systems

Abstract Rule-based systems can be viewed as possessing two sets of properties: static and dynamic. Static properties are those that can be evaluated without executing the system, and dynamic properties can be evaluated only by examining how the system operates at run time. The dynamic properties of a rule-based system have been largely neglected in validation and verification work done thus far. Structural verification and static testing techniques do not yield information on how a rule-based system achieves its goals at run-time, given a set of input data. This paper presents a model for the relationship between the goal states achieved by a rule-based system, the set of inter-related rules that must fire to achieve each goal state, and the data items required for the rules in the rule sequence to fire. Then, we describe a method for applying this model to study the dynamic properties of a rule-based system. It is demonstrated that this model permits the validation of dynamic properties of a rule-based system, enabling system developers to decide: (1) if the manner in which the system pursues goals is valid according to the specifications (and expectations) of the designers; (2) what relationship exists between the quality of system output for a given test case and the goals achieved during problem-solving on that test case; and (3) how the overall problem-solving activity of the system relates to the availability of input data.

Characterising Context for Mobile User Interfaces in Health Care Applications

Mobile technology has been piloted in a variety of domains. We investigate the use of smart phones in the hospital environment, as they can play an important role in the recording and exchanging of information. This paper examines how context can be characterised for developing context sensitive user interfaces for smart phone application in a hospital environment. We introduce a new characterisation of the notion of context, based on the principle of separation of the concerns that are relevant to the application domain. We coin the term context descriptor, which captures the notion of context at the end-user level, while the characterisation of the context incorporates the user model via the user stereotype. We use a sub-domain of health care, nursing services, the tasks of the nurses serving as a living example to illustrate the ideas presented.

A New Quality-in-Use Model for Mobile User Interfaces

This paper proposes a new quality-in-use model for measuring user interface design quality, and is intended specifically for mobile devices. The proposed model is based on the international standard ISO 9126-4 [ISO/IEC TR 9126-4:2004] and can be adapted to various applications. The quality-in-use factors of effectiveness, productivity, efficiency, safety, and satisfaction are redefined to reflect the ways in which mobile devices are used, and the contexts in which they are used. A new factor, task navigation, is proposed to measure the cognitive load on the user when he or she interacting with the interface across different platforms. Our objectives include theoretical and empirical validation of the proposed measurement model.

Context-based and Rule-based Adaptation of Mobile User Interfaces in mHealth☆

Abstract Mobile technology is an integral part of the modern health care environment. In mHealth, the mobile user interface (MUI) serves as the bridge between the application and the health care professional. It is important that the doctor be able to easily express his needs on the MUI and correctly interpret the information displayed. New techniques for adapting MUIs offer new opportunities for the MUI designer to maximize the benefits of mHealth technology by providing the best possible way for health care professionals to perform their tasks efficiently and effectively. For the designer, the hope is that new technologies will be developed, such as mobile devices adaptable to different environments, so as to enable customization of the application to the users context. In this paper, we propose context-based and rule-based approach for designing adaptable MUIs in mHealth. The MUI features adapted to the needs of health care professionals have been implemented on the iPhone and evaluated with an empirical study.

A New Methodology (CON-INFO) for Context-Based Development of a Mobile User Interface in Healthcare Applications

Mobile technology is an integral part of the modern healthcare environment. In Pervasive Healthcare, the Mobile User interface (MUI) serves as the bridge between the application and the healthcare professional. It is important that the doctor be able to easily express his needs on the MUI and correctly interpret the information displayed. The context-based MUI design methodology developed in this chapter offers a new approach to automated MUI context adaptation. This methodology for designing an adaptable context-dependent MUI for healthcare applications provides a solution that makes essential patient information available to doctors in an easily accessible, clear, and accurate way, and at any time. The quality-in-use of the MUI designed with this methodology is monitored using a new measurement model inspired by the ISO 25010 international standard and adapted to healthcare. The measurement model is validated both theoretically and empirically. The benefits of the proposed methodology for healthcare professionals include improved productivity, performance, and level of satisfaction, as well as increased patient safety, as doctors can access patient information whenever it is needed. The methodology is illustrated on a case study.

Structure-based validation of rule-based systems

A central problem in validating rule-based systems is ensuring that the structural components of the system have been tested sufficiently thoroughly. In this paper, we present a method that can be used for structure-based testing of rule-based systems. Our method includes a model for determining the structural components in a rule base, a metric for quantifying coverage (the degree to which the structural components in a rule base have been tested) and techniques for analyzing the coverage obtained when a rule base is exercised on a given test set. We present the results produced by applying our method for structure-based testing to a complex rule-based system that had been previously subjected to functional testing. The results we obtained indicate that our method for structure-based testing reveals several types of faults not shown by previous testing, and quantifies the extent to which the rule base has been tested.