Effects of structure on the comprehensibility of formal specifications

Use of structuring mechanisms (such as modularisation) is widely believed to be one of the key ways to improve software quality. Structuring is considered to be at least as important for specification documents as for source code, since it is assumed to improve comprehensibility. Yet, as with most widely held assumptions in software engineering, there is little empirical evidence to support this hypothesis. Also, even if structuring can be shown to he a good thing, we do not know how much structuring is somehow optimal. One of the more popular formal specification languages, Z, encourages structuring through its schema calculus. A controlled experiment is described in which two hypotheses about the effects of structure on the comprehensibility of Z specifications are tested. Evidence was found that structuring a specification into schemas of about 20 lines long significantly improved comprehensibility over a monolithic specification. However, there seems to be no perceived advantage in breaking down the schemas into much smaller components. The experiment can he fully replicated.

A versatile policy toolkit supporting run-time policy reconfiguration

This paper describes an autonomics development tool which serves as both a powerful and flexible policy-expression language and a policy-based framework that supports the integration and dynamic composition of several autonomic computing techniques including signal processing, automated trend analysis and utility functions. Each of these technologies has specific advantages and applicability to different types of dynamic adaptation. The AGILE platform enables seamless interoperability of the different technologies to each perform various aspects of self-management within a single application. Self-management behaviour is specified using the policy language semantics to bind the various technologies together as required. Since the policy semantics support run-time re-configuration, the self-management architecture is dynamically composable. The policy language and implementation library have integrated support for self-stabilising behaviour, enabling oscillation and other forms of instability to be handled at the policy level with very little effort on the part of the application developer. Example applications are presented to illustrate the integration of different autonomics techniques, and the achievement of dynamic composition.

Dizzy heights and occupiers' liability

Reviews case law on the occupier's duty of care to trespassers under the Occupiers' Liability Act 1984 s.1, including the issues that apply where the trespasser engaged in risky behaviour, was a child, and where the property was inherently dangerous.

An evaluation of a community matron service from the patients’ perspective

Community matrons are a relatively new government initiative aimed at case managing people with long-term conditions to reduce the number of emergency bed days used in hospitals. Although there have been extensive evaluations of similar case management projects, to date there has been little evaluation of the community matron's role and the perceptions patients have of this new service. One of the main Government agendas for care is to deliver a high quality service driven by the needs of the service users (DH, 2000). In order to drive this agenda, care is to deliver a high quality service driven by the needs of the service users (DH, 2000). In order to drive this agenda, it is important that the views and perceptions of people on the receiving end of the services are heard, valued and appropriate actions taken. This two part evaluative report sets out to explore how people with long-term conditions perceive the impact of community matrons and the differences this new service may have had on their lives. Questionnaires were sent to 100 patients who were currently being case-managed by a community matron to evaluate the community matron service from the patients' perspective. Part two reports on patients' perceptions of the community matron role and the influences of the role on their health.