Integration of the Different Elements of Object-Oriented Software Engineering into a Conceptual Framework: The 3D-Model

This report describes a conceptual framework for supporting software engineering. The approach relies on object-oriented concepts, but is not limited to object-oriented software engineering. The basic idea is the notion of a three-dimensional graph structure, which serves to capture and to classify development activities and their resulting documents (the elements of software engineering). The three dimensions - views, components, development process - of a (software) system serve as fundamental organizing principles, according to which all elements are placed into a uniform, intuitive, but formal meta-structure. From this meta-structure - the so-called 3D-model - relevant development elements (activities, specifications) and their relationships with other elements can be derived, together with suitable notations and a process. Hence, the 3D-model offers a mechanism to define an effective and tailored software development process, which offers freedom to select its notations, methods, ..

GRaph-based, Integrated Development of Software: Integrating Different Perspectives of Software Engineering

Goal of the GRIDS project is to provide a formally based, multi-dimensional software engineering model - and tool - that integrates "partial" models of software processes, system architectures, and views onto the system into one consistent project framework, in order to enhance real-life, large-scale software development. In this paper, we first introduce the static part of the so-called Three-Dimensional Model of Software Engineering (3DM ), which captures and structures partial models, integrated project frameworks, and other relevant project information. We further describe the dynamic part of the 3DM , which provides the necessary actions to generate, manipulate and maintain the entities of the static part. Using the programmed graph rewriting system PROGRES gives us a powerful means to formally specify our conceptual model. We show how we apply PROGRES to formalize the 3DM , and present the prototype of a tool, generated from the formal specification of the static and dynamic pa..

Integrating the Developers' and the Management's Perspective of an Incremental Development Life Cycle

Purely sequential life cycles can't cope with the developer's need for relatively unrestricted and "unordered" creativity when dealing with the development of innovative software systems. Nevertheless, project management usually favors sequential project phasing, because sequential processes are easier to plan, control and monitor. In this paper, we present a life cycle plan that integrates an incremental and iterative development style, relying on evolutionary prototyping, with the management's perspective of clear and unambiguous project phasing. As consequence of applying this "hybrid" life cycle plan, the quality of innovative, complex software systems can be increased, while risks can be detected better and earlier. We support validity of our approach by also reporting experiences we made when applying the life cycle plan to two large, multilateral software projects, and compare them to two systems developed following the traditional approach. Keywords: incremental development, l..

Validating Database Components of Software Systems

In this article, we present a framework and a concrete method to support validation of central database components in application software. We explain how validation can cope with both the need for a formalized evaluation of correctness as well as the need for prototyping high level database specifications in early development phases. We define different levels of correctness suitable for database specifications and show how these levels can be checked by our validation method. For this purpose, we describe both the method's formal basis and explain step-by-step the corresponding pragmatic algorithm to actually generate test data and validate the specification. Keywords: consistency, correctness, database-centered application software, extended ER model, high level database specification, prototyping, test data, validation method 1 Introduction In the area of software engineering, testing has a well-known tradition and corresponding theories exist [1, 2, 19]. These approaches focus o..

Enhancing the Quality of Conceptual Database Specifications through Validation

In this article, we present a validation approach and method to support the development of database applications. We explain how validation can cope both with the need for a formalized evaluation of correctness as well as the need for prototyping of conceptual database schemata. We define different levels of correctness for such schemata and show how these levels can be achieved through validation methods. Furthermore, we describe how our validation framework can be applied to other conceptual specifications. Keywords: consistency, correctness, database application, database schema, database specification, extended ER model, test data, validation 1 Introduction One of the main questions for the development of database specifications is: How can we ensure that our specification is correct and reflects the desired portion of reality? In times of increasingly complex specifications of database applications, we need well-structured approaches to handle this complexity and guarantee qua..

Evolutionary Software Development: An Experience Report on Technical and Strategic Requirements

Traditional software engineering approaches are no longer suitable when dealing with the development of innovative, complex software systems, such as e.g. applications of neural networks for geophysical subsurface modeling. At TNO, we succeeded to define and to establish a "hybrid" life cycle plan that integrates the developers' view of a creative, flexible and unrestricted development process on the basis of evolutionary prototyping with the management's needs for organization, controllability, and clearness of a software project. We report the experiences we made when applying the evolutionary life cycle plan to multilateral software projects, and compare them with systems developed following the traditional approach. In this paper, we focus on the most crucial technical and strategic requirements for (controlled) evolutionary software development. We discuss the issues of team structure, commitment of, and communication with users, frequent testing, integration & version control, co..

Development of a prediction model for postoperative pneumonia A multicentre prospective observational study

BACKGROUND Postoperative pneumonia is associated with increased morbidity, mortality and costs. Prediction models of pneumonia that are currently available are based on retrospectively collected data and administrative coding systems. OBJECTIVE To identify independent variables associated with the occurrence of postoperative pneumonia. DESIGN A prospective observational study of a multicentre cohort (Prospective Evaluation of a RIsk Score for postoperative pulmonary COmPlications in Europe database). SETTING Sixty-three hospitals in Europe. PATIENTS Patients undergoing surgery under general and/or regional anaesthesia during a 7-day recruitment period. MAIN OUTCOME MEASURE The primary outcome was postoperative pneumonia. Definition: the need for treatment with antibiotics for a respiratory infection and at least one of the following criteria: new or changed sputum; new or changed lung opacities on a clinically indicated chest radiograph; temperature more than 38.3 degrees C; leucocyte count more than 12 000 mu l(-1). RESULTS Postoperative pneumonia occurred in 120 out of 5094 patients (2.4%). Eighty-two of the 120 (68.3%) patients with pneumonia required ICU admission, compared with 399 of the 4974 (8.0%) without pneumonia (P < 0.001). We identified five variables independently associated with postoperative pneumonia: functional status [odds ratio (OR) 2.28, 95% confidence interval (CI) 1.58 to 3.12], pre-operative SpO(2) values while breathing room air (OR 0.83, 95% CI 0.78 to 0.84), intra-operative colloid administration (OR 2.97, 95% CI 1.94 to 3.99), intra-operative blood transfusion (OR 2.19, 95% CI 1.41 to 4.71) and surgical site (open upper abdominal surgery OR 3.98, 95% CI 2.19 to 7.59). The model had good discrimination (c-statistic 0.89) and calibration (Hosmer-Lemeshow P = 0.572). CONCLUSION We identified five variables independently associated with postoperative pneumonia. The model performed well and after external validation may be used for risk stratification and management of patients at risk of postoperative pneumonia