Applying ArchOptions to value the payoff of refactoring

ArchOptions is a real-options based model that we have pro-posed to value the flexibility of software architectures in response to future changes in requirements. In this paper, we build on ArchOptions to devise an options-based model, which values the architectural flexibility that results from a refactoring exercise. This value assists in understanding the payoff of investing in refactoring: if the refactored system results in an architecture that is more flexible, such that the expected added value (in the form of options) due to the en-hanced flexibility outweighs the cost of investing in this exer-cise, then refactoring is said to payoff. We apply our model to a refactoring case study from the literature

Contingent Information Systems Development

Situated approaches based on project contingencies are becoming more and more an important research topic for information systems development organizations. The Information Services Organization, which was investigated, has recognized that it should tune its systems development approaches to the specific situation. A model has been developed, dealing with the matching between prevailing contingency factors and the preconditions of already existing situated approaches. Furthermore, a generic process model for systems development, including the information systems operations stage, is proposed. This model makes it possible to derive from it specific systems development strategies. A number of basic development strategies, specific for the Information Services Organization, are described. Preconditions, specific for this organization, are added to the standard situated approaches

Using real options to select stable Middleware-induced software architectures

The requirements that force decisions towards building distributed system architectures are usually of a non-functional nature. Scalability, openness, heterogeneity, and fault-tolerance are examples of such non-functional requirements. The current trend is to build distributed systems with middleware, which provide the application developer with primitives for managing the complexity of distribution, system resources, and for realising many of the non-functional requirements. As non-functional requirements evolve, the `coupling' between the middleware and architecture becomes the focal point for understanding the stability of the distributed software system architecture in the face of change. It is hypothesised that the choice of a stable distributed software architecture depends on the choice of the underlying middleware and its flexibility in responding to future changes in non-functional requirements. Drawing on a case study that adequately represents a medium-size component-based distributed architecture, it is reported how a likely future change in scalability could impact the architectural structure of two versions, each induced with a distinct middleware: one with CORBA and the other with J2EE. An option-based model is derived to value the flexibility of the induced-architectures and to guide the selection. The hypothesis is verified to be true for the given change. The paper concludes with some observations that could stimulate future research in the area of relating requirements to software architectures

Industry views on water resources planning methods – prospects for change in England and Wales

This paper describes a qualitative study of practitioner perspectives on regulated water resources planning practice in England and Wales. The study focuses on strengths and weaknesses of existing practice and the case for change towards a risk-based approach informed by stochastic modelling assessments. In-depth, structured interviews were conducted to capture the views of planners, regulators and consultants closely involved in the planning process. We found broad agreement that the existing water availability assessment methods are fallible; they lack transparency, are often highly subjective and may fail to adequately expose problems of resilience. While most practitioners believe these issues warrant a more detailed examination of risk in the planning process, few believe there is a strong case for a fundamental shift towards risk-based planning informed by stochastic modelling assessments. The study identifies perceived business risks associated with change and exposes widespread scepticism of stochastic methods

An Assessment of PIER Electric Grid Research 2003-2014 White Paper

This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California’s California Institute for Energy and the Environment, from 2003-2014

Investigation of Air Transportation Technology at Princeton University, 1989-1990

The Air Transportation Technology Program at Princeton University proceeded along six avenues during the past year: microburst hazards to aircraft; machine-intelligent, fault tolerant flight control; computer aided heuristics for piloted flight; stochastic robustness for flight control systems; neural networks for flight control; and computer aided control system design. These topics are briefly discussed, and an annotated bibliography of publications that appeared between January 1989 and June 1990 is given