Hong Yul Yang

Detecting indirect coupling

Coupling is considered by many to be an important concept in measuring design quality There is still much to be learned about which aspects of coupling affect design quality or other external attributes of software. Much of the existing work concentrates on direct coupling, that is, forms of coupling that exists between entities that are directly related to each other. A form of coupling that has so far received little attention is indirect coupling, that is, coupling between entities that are not directly related. What little discussion there is in the literature suggests that any form of indirect coupling is simple the transitive closure of a form of direct coupling. We demonstrate that this is not the case, that there are forms of indirect coupling that cannot be represented in this way and suggest ways to measure it. We present a tool that identifies a particular form of indirect coupling that is integrated in the Eclipse IDE.

Model Driven Development of Clinical Information Systems using openEHR

openEHR and the recent international standard (ISO 13606) defined a model driven software development methodology for health information systems. However there is little evidence in the literature describing implementation; especially for desktop clinical applications. This paper presents an implementation pathway using .Net/C# technology for Microsoft Windows desktop platforms. An endoscopy reporting application driven by openEHR Archetypes and Templates has been developed. A set of novel GUI directives has been defined and presented which guides the automatic graphical user interface generator to render widgets properly. We also reveal the development steps and important design decisions; from modelling to the final software product. This might provide guidance for other developers and form evidence required for the adoption of these standards for vendors and national programs alike.

Evaluation of software maintainability with openEHR – a comparison of architectures

PURPOSE To assess whether it is easier to maintain a clinical information system developed using open EHR model driven development versus mainstream methods. METHODS A new open source application (GastrOS) has been developed following open EHRs multi-level modelling approach using .Net/C# based on the same requirements of an existing clinically used application developed using Microsoft Visual Basic and Access database. Almost all the domain knowledge was embedded into the software code and data model in the latter. The same domain knowledge has been expressed as a set of open EHR Archetypes in GastrOS. We then introduced eight real-world change requests that had accumulated during live clinical usage, and implemented these in both systems while measuring time for various development tasks and change in software size for each change request. RESULTS Overall it took half the time to implement changes in GastrOS. However it was the more difficult application to modify for one change request, suggesting the nature of change is also important. It was not possible to implement changes by modelling only. Comparison of relative measures of time and software size change within each application highlights how architectural differences affected maintain ability across change requests. CONCLUSIONS The use of open EHR model driven development can result in better software maintain ability. The degree to which open EHR affects software maintain ability depends on the extent and nature of domain knowledge involved in changes. Although we used relative measures for time and software size, confounding factors could not be totally excluded as a controlled study design was not feasible.