In many cases, the programmer may require to encode business rules into the database applications. To do this, a large number of program elements may need to be examined by the programmer, to determine which have the capacity to violate a new rule and if so what minimal changes are required to prevent such violations. This process can be time-consuming, and even seasoned programmers can miss difficult and obscure cases in the mass of code. In this paper, we describe a static source code analysis technique to assist the programmer in enforcing business rules in a way that cuts down the amount of irrelevant code to be examined. Our technique derives all the possible ways in which a new business rule can be violated by the programs in the system being modified, and the specific program elements responsible.

Modern software development practices show that there is significant diversity in the product, process and geographical location of software development due to economical, technical and logistical constraints. Such diverse development demands flexibility in the software engineering methodology. In this paper, we propose the cellular development methodology (CDM), an architecture-driven approach to flexible software development. CDM derives the development process and its architecture from the software architecture of product. The software development process is structured and customised as a network of cooperating cells. Our contribution is a cellular approach to software development based on the software architecture of the end product whereby a network of configurable cells yield customisable, potentially distributed software development processes which in turn produce software that is highly tailored to user requirements.

Many software systems implement, amongst other things, a collection of business rules. However, the process of evolving the business rules associated with a system is both time consuming and error prone. In this paper, we propose a novel approach to facilitating business rule evolution through capturing information to assist with the evolution of rules at the point of implementation. We analyse the process of rule evolution, in order to determine the information that must be captured. Our approach allows programmers to implement rules by embedding them into application programs (giving the required performance and genericity), while still easing the problems of evolution.

Software that cannot evolve is condemned to atrophy: it cannot accommodate the constant revision and re-negotiation of its business goals nor intercept the potential of new technology. To accommodate change in software systems, we have defined an active software architecture to be: dynamic in that the structure and cardinality of the components and interactions are changeable during execution; updatable in that components can be replaced; decomposable in that an executing system may be (partially) stopped and split up into its components and interactions; and reflective in that the specification of components and interactions may be evolved during execution. Here we describe the facilities of the ArchWare architecture description language (ADL) for specifying active architectures. The contribution of the work is the unique combination of concepts including: a /spl pi/-calculus based communication and expression language for specifying executable architectures; hyper-code as an underlying representation of system execution that can be used for introspection; a decomposition operator to incrementally break up executing systems; and structural reflection for creating new components and binding them into running systems.

My Grid is an e-Science Grid project that aims to help biologists and bioinformaticians to perform workflow-based in silico experiments, and help them to automate the management of such workflows through personalisation, notification of change and publication of experiments. In this paper, we describe the architecture of my Grid and how it will be used by the scientist. We then show how my Grid can benefit from agents technologies. We have identified three key uses of agent technologies in my Grid: user agents, able to customize and personalise data, agent communication languages offering a generic and portable communication medium, and negotiation allowing multiple distributed entities to reach service level agreements.

The changing needs of modern application systems demand new and radical software architectures to support them. The attraction of persistent systems is that they define precisely the extent to which they are open, thereby allowing the dynamically changing resource requirements of applications to be tracked accurately within the persistent environment. Thus, an ever-growing body of work is being established to study the nature of running applications, and to use the information gleaned, to improve the run-time execution of these applications. Here we propose a new architectural approach to constructing persistent systems that accommodates, and thus is compliant to, the needs of particular applications. By separating policy from mechanism in all components, the architecture may be tailored to the policy needs of the application. (Policy may be regarded as strategy for achieving a goal, such as a cache eviction algorithm, whereas mechanism is the method by which the objective is achieved, such as the physical movement of the cache lines. As we see later, policy and mechanism are composable to form new mechanism.) We first propose a generic architecture for compliance, and then show how it may be instantiated. Finally, we describe an example of how the architecture operates in a manner that is compliant to a target application. We postulate, since we have not yet measured, that the benefits of compliant architectures will be a reduction in complexity, with corresponding gains in flexibility, portability, understandability in terms of failure semantics, and performance. Copyright © 2000 John Wiley & Sons, Ltd.

The cost-effective and reliable evolution of systems is a significant software engineering challenge. Our approach is based on a combination of product modelling, process modelling and software metrics. We describe an empirical laboratory study following the evolution of three releases of a publicly available exemplar system. Analysis of the metrics which were collected improves our understanding of how a system evolves. Process metrics can provide information about how the product is put together, and product metrics suggest explanations for the development processes observed.